Patent Publication Number: US-2022230483-A1

Title: Vehicle diagnosis system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-006385 filed on Jan. 19, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a vehicle diagnosis system. 
     2. Description of Related Art 
     The control device of a vehicle disclosed in Japanese Patent No. 4706890 (JP 4706890 B) can execute a diagnosis process of diagnosing a failure of a vehicle when a user feels some kind of abnormal change in the vehicle. The control device executes the diagnosis process in response to a command from the user. When executing the diagnosis process, the control device locates the failed part and urges the user to take the vehicle to a dealer. 
     SUMMARY 
     Some failures of a vehicle, depending on their nature, are less likely to cause the user to feel an abnormal change. In the technique of JP 4706890 B, the control device does not execute the diagnosis process unless the user feels an abnormal change and gives a command to the control device to execute the diagnosis process. Thus, if such a failure as not to cause the user to feel an abnormal change occurs, this technique cannot ascertain that failure by executing the diagnosis process. 
     A vehicle diagnosis system for solving this problem has: a diagnosis device that diagnoses an abnormality of a part separating the inside and the outside of a vehicle cabin in a vehicle; a sound source that is located outside the vehicle cabin and emits a sound of which at least one of the sound pressure and the frequency is predetermined; and a microphone located inside the vehicle cabin. The diagnosis device executes: an acquisition process of, when the sound source emits a sound, acquiring detected sound data about the sound as detected by the microphone; and a determination process of determining whether the part has an abnormality by comparing the detected sound data with predetermined reference sound data. 
     In this configuration, the diagnosis device determines whether the part separating the inside and the outside of the vehicle cabin has an abnormality by comparing the detected sound data based on a sound detected by the microphone with the reference sound data. Since the diagnosis device acquires this detected sound data when the sound source installed in the vehicle emits a sound, the diagnosis device can acquire the detected sound data also when the user has not felt an abnormality of the part. Thus, the vehicle diagnosis system of this configuration can determine whether the part has an abnormality regardless of whether the user has felt an abnormality of the part. 
     In the vehicle diagnosis system, the sound pressure of a sound emitted by the sound source may be predetermined. In the determination process, the diagnosis device may determine whether the part has an abnormality based on a difference between a sound pressure in the detected sound data and a sound pressure in the reference sound data. 
     When the part separating the inside and the outside of the vehicle cabin has an abnormality, a sound emitted by the sound source may reach into the vehicle cabin more easily. In this case, the sound detected by the microphone is likely to have a higher sound pressure. By making a determination using this characteristic, the vehicle diagnosis system of the above configuration can appropriately determine an abnormality of the part separating the inside and the outside of the vehicle cabin. 
     In the vehicle diagnosis system, the frequency of a sound emitted by the sound source may be predetermined. When a rate at which the sound pressure decays after the sound has been emitted from the sound source is called a rate of sound pressure decay, in the determination process, the diagnosis device may determine whether the part has an abnormality based on a difference between a rate of sound pressure decay in the detected sound data and a rate of sound pressure decay in the reference sound data. 
     When the part separating the inside and the outside of the vehicle cabin has an abnormality, a sound reaching into the vehicle cabin from the outside may decay less inside the vehicle cabin. In this case, the sound detected by the microphone is likely to have a lower decay rate. By making a determination using this characteristic, the vehicle diagnosis system of the above configuration can appropriately determine an abnormality of the part separating the inside and the outside of the vehicle cabin. 
     In the vehicle diagnosis system, the sound source may emit a sound for alerting those around the vehicle to the presence of the vehicle. In the determination process, the diagnosis device may determine, while the vehicle is traveling, whether the part has an abnormality by comparing detected sound data about the sound emitted by the sound source with reference sound data relating to the sound. 
     Using the sound source that emits a sound for alerting those around the vehicle to the presence of the vehicle as in this configuration can eliminate the need for adding a sound source to the vehicle just for diagnostic purposes. The sound that the sound source emits while the vehicle is traveling is emitted independently of whether the user has felt some kind of abnormality of the part. Thus, whether the part has an abnormality can be determined regardless of whether the user has felt an abnormality of the part. 
     In the vehicle diagnosis system, the sound source may emit the sound when the vehicle has stopped inside a predetermined area. In the determination process, the diagnosis device may determine whether the part has an abnormality by comparing detected sound data about the sound emitted by the sound source when the vehicle has stopped with reference sound data relating to the sound. Emitting a sound from the sound source when the vehicle has stopped inside a predetermined area as in this configuration can increase the opportunities to perform the determination process. 
     In the vehicle diagnosis system, the diagnosis device may be installed in the vehicle. In this configuration, the part separating the inside and the outside of the vehicle cabin can be diagnosed in the vehicle. This can simplify the system configuration compared with when the diagnosis device is provided in some other place than the vehicle. 
     The vehicle diagnosis system may include an external device capable of wireless communication with the vehicle. The diagnosis device may be provided in the external device and store pieces of the reference sound data for a plurality of vehicle types so as to correspond to the respective vehicle types. In the acquisition process, the diagnosis device may acquire, from a vehicle to be diagnosed that is a vehicle for which an abnormality of the part is to be diagnosed, the detected sound data and vehicle type information on the vehicle to be diagnosed. In the determination process, the diagnosis device may compare the detected sound data acquired by the acquisition process with reference sound data corresponding to the vehicle type of the vehicle to be diagnosed. 
     This configuration makes it possible to share the external device equipped with the diagnosis device among a plurality of vehicles and thereby simplify the management of the diagnosis device. Moreover, since whether there is an abnormality is determined using the reference sound data corresponding to the vehicle type of the vehicle to be diagnosed, high abnormality determination accuracy can be achieved. 
     In the vehicle diagnosis system, the part may be a part that separates an engine compartment or a motor compartment of the vehicle and the vehicle cabin from each other. In this configuration, whether the part separating the engine compartment or the motor compartment and the vehicle cabin from each other has an abnormality can be determined. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a schematic configuration diagram of a vehicle shared use system; 
         FIG. 2  is a schematic configuration diagram of a vehicle; 
         FIG. 3  is a flowchart showing a processing procedure of a diagnosis process; 
         FIG. 4  is a schematic diagram of a management server and a vehicle; and 
         FIG. 5  is a flowchart showing processing procedures of a diagnosis assistance process and a server-conducted diagnosis process. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     A first embodiment of a vehicle diagnosis system will be described below with reference to  FIG. 1  to  FIG. 3  of the drawings. 
     In the following, the vehicle diagnosis system will be described using, as an example, a case where an object to be diagnosed is a vehicle that is capable of autonomously traveling without requiring a driver&#39;s operation and belongs to a shared use system in which an unspecified large number of users make shared use of vehicles. 
     General Configuration of Shared Use System 
     As shown in  FIG. 1 , a vehicle shared use system  10  has a management server  20 , a plurality of vehicles  30 , and a user terminal  14 . 
     The user terminal  14  is a terminal used by a user who uses the vehicle  30 . The user terminal  14  is, for example, a smartphone. The user terminal  14  can send and receive information to and from the management server  20  through an external communication network  12 . The user terminal  14  sends user application information to the management server  20  according to an input operation by the user. The user application information includes pieces of information such as a usage start location, a destination, and a usage start time and date of the vehicle  30 . The usage start location is a point to which the user requests that the vehicle  30  be delivered. The usage start time and date are time and date when the user requests that the vehicle  30  be delivered. 
     The management server  20  is a server that manages the vehicles  30 . The management server  20  can be configured as one or more processors that execute various processes in accordance with computer programs (software). Alternatively, the management server  20  may be configured as one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that execute at least some of the various processes, or as a circuitry including a combination of these dedicated hardware circuits. The processor includes a CPU and a memory, such as a RAM and a ROM. The memory holds program codes or commands configured to cause the CPU to execute processes. The memory, i.e., a computer-readable medium, may be any available medium that can be accessed by a general-purpose or dedicated computer. The management server  20  has a storage device that is an electrically rewritable non-volatile memory. The management server  20  has a communication instrument that connects the management server  20  to an outside through the external communication network  12 . The management server  20  constitutes an external device that is a processing device provided outside the vehicle  30 . 
     The management server  20  stores pieces of individual identification information for the respective vehicles  30  so as to be able to individually identify the vehicles  30 . The individual identification information includes pieces of information such as the vehicle type, the vehicle body manufacturing number, and the automobile registration number certificate of the vehicle  30 . The management server  20  sends various pieces of information to each vehicle  30  by wireless communication through the external communication network  12 . For example, the management server  20  sends to each vehicle  30  information about the destination to which the vehicle  30  should travel. The destination is sometimes the usage start location requested by the user and other times a vehicle base. The vehicle base is a parking lot where the vehicles  30  are parked when not used by users. 
     General Configuration of Vehicle 
     The vehicles  30  are electric vehicles. The vehicles  30  differ in vehicle type but have the same basic configuration. In the following, the basic configuration of the vehicles  30  will be described. 
     As shown in  FIG. 2 , each vehicle  30  has a motor compartment  32 , a dashboard panel  35 , and a vehicle cabin  31 . The motor compartment  32  is a space defined at a part of the vehicle  30  closer to a front side. The dashboard panel  35  is a wall that defines a rear end of the motor compartment  32 . The dashboard panel  35  has a plate shape. The vehicle cabin  31  is a space defined on the opposite side of the dashboard panel  35  from the motor compartment  32 . Thus, the dashboard panel  35  separates the motor compartment  32  and the vehicle cabin  31  from each other. While this is not shown, the components of the dashboard panel  35  include a plate-shaped dashboard panel main body and an acoustic insulator mounted on the dashboard panel main body. A plurality of mounting parts extends through the dashboard panel main body and the acoustic insulator. These mounting parts integrally fix the dashboard panel main body and the acoustic insulator. 
     The vehicle  30  has a motor-generator  37 , a battery  38 , and drive wheels  39 . The motor-generator  37  is a drive source of the vehicle  30 . The motor-generator  37  is a power generating electric motor that has the functions of both an electric motor and a power generator. The motor-generator  37  is electrically connected to the battery  38  through an inverter. The battery  38  supplies electricity to the motor-generator  37  as well as stores electricity supplied from the motor-generator  37 . The inverter performs power conversion between direct current and alternating current. In  FIG. 2 , the inverter is not shown. 
     The motor-generator  37  is located inside the motor compartment  32 . A rotating shaft of the motor-generator  37  is coupled to the drive wheels  39  through power transmission mechanisms such as a torque converter, a transmission, a clutch, and a differential. In  FIG. 2 , the power transmission mechanisms are not shown. 
     The vehicle  30  has a plurality of seats  40  and a plurality of pressure sensors  41 . The seats  40  are seats on which occupants sit. The seats  40  are located inside the vehicle cabin  31 . The pressure sensors  41  are mounted in the respective seats  40 . Each pressure sensor  41  detects a seat pressure W that is a pressure applied to a seat surface of the seat  40 . In  FIG. 2 , only one of the seats  40  is shown. In  FIG. 2 , only one of the pressure sensors  41  is shown. 
     The vehicle  30  has an alarm  33 , a horn  34 , and a microphone  36 . The alarm  33  is a sound source that emits a sound of which the sound pressure and the frequency are predetermined. The alarm  33  emits a warning sound for alerting those around the vehicle  30  to the presence of the vehicle  30  while the vehicle  30  is traveling at low speed. For example, the warning sound emitted by the alarm  33  is a sound that mimics the operating sound of a motor and is set as such a relatively small sound as not to constitute noise. The alarm  33  is located inside the motor compartment  32 . The horn  34  is a sound source that emits a sound of which the sound pressure and the frequency are predetermined. The horn  34  emits a honk for alerting those around the vehicle  30  to the presence of the vehicle  30  while the vehicle  30  is traveling or stationary. The honk emitted by the horn  34  is set to be louder than the warning sound. The horn  34  is located inside the motor compartment  32 . The microphone  36  detects a sound pressure level L that is a sound pressure in a predetermined frequency band expressed in decibels. The microphone  36  is located inside the vehicle cabin  31 . The warning sound emitted by the alarm  33  is set to a predetermined sound pressure level L. The honk emitted by the horn  34  is set to a predetermined sound pressure level L different from that of the warning sound. 
     The vehicle  30  has turn signals, hazard flashers, wipers, an air conditioner, and power windows. The turn signals are directional indicators. The hazard flashers are devices that turn emergency flashing lights on. The wipers are devices that remove raindrops, dirt, and dust adhering to a windshield and a rear window. The air conditioner is an air conditioning device. The power windows are electrically operated window opening-closing devices. In  FIG. 2 , these various devices are collectively represented by reference sign M. 
     The vehicle  30  has a vehicle speed sensor  42 , a GPS receiver  43 , a camera  44 , and a radar  45 . The vehicle speed sensor  42  detects a vehicle speed SP that is a travel speed of the vehicle  30 . The GPS receiver  43  receives a signal relating to a current position coordinate G of the vehicle  30  from a GPS satellite. The camera  44  images the surroundings of the vehicle  30 . The radar  45  detects an obstacle Z by sending an electric wave and receiving the electric wave reflected by the obstacle Z. 
     General Configuration of Control Device of Vehicle 
     The vehicle  30  has a control device  50 . The control device  50  can be configured as one or more processors that execute various processes in accordance with computer programs (software). Alternatively, the control device  50  may be configured as one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that execute at least some of the various processes, or as a circuitry including a combination of these dedicated hardware circuits. The processor includes a CPU and a memory, such as a RAM and a ROM. The memory holds program codes or commands configured to cause the CPU to execute processes. The memory, i.e., a computer-readable medium, may be any available medium that can be accessed by a general-purpose or dedicated computer. The control device  50  has a storage device that is an electrically rewritable non-volatile memory. The control device  50  has a communication instrument that connects the control device  50  to the outside of the vehicle  30  through the external communication network  12 . The control device  50  stores individual identification information about the vehicle  30  in which the control device  50  is installed. The contents of the individual identification information are the same as those stored in the management server  20 . 
     The control device  50  switches between an on state and a standby state. The on state is a state where a main system for operating various parts of the vehicle  30  has been started. When the main system is started in the control device  50 , electricity is supplied to various parts of the vehicle  30 , including the motor-generator  37  and the various devices M. The standby state is a state where the main system has been shut down and a command for starting the main system is waited for. In the standby state, the supply of electricity to various parts of the vehicle  30  is interrupted. In the standby state, the supply of electricity from the outside to the control device  50  is also interrupted. However, the control device  50  can operate on electricity of its own built-in battery. The control device  50  switches between the standby state and the on state in response to a command from the management server  20 . 
     The control device  50  receives the vehicle speed SP detected by the vehicle speed sensor  42 . The control device  50  receives a signal relating to the current position coordinate G received by the GPS receiver  43 . The control device  50  receives a signal relating to imaging information J that is information imaged by the camera  44 . The control device  50  receives a signal relating to the obstacle Z detected by the radar  45 . The control device  50  receives a signal relating to the seat pressure W detected by the pressure sensor  41 . The control device  50  receives a signal relating to the sound pressure level L detected by the microphone  36 . 
     The control device  50  has an overall control unit  52  that controls various parts of the vehicle  30 . While the main system is on, the overall control unit  52  controls various parts of the vehicle  30  to perform autonomous driving of the vehicle  30 . Autonomous driving refers to making the vehicle  30  travel autonomously without the driver&#39;s operation. For example, based on the imaging information J from the camera  44 , the overall control unit  52  makes the vehicle  30  travel while keeping the vehicle  30  in the lane and maintaining the following distance to the vehicle traveling ahead. Further, for example, based on the information on the obstacle Z detected by the radar  45 , the overall control unit  52  makes the vehicle  30  travel so as to avoid the obstacle Z. The overall control unit  52  calculates a travel route for the vehicle  30  to take toward the destination. The overall control unit  52  stores map data as data required for calculating the travel route of the vehicle  30 . The map data includes pieces of information such as roads and buildings. Based on the current position coordinate G of the vehicle  30  received from the GPS receiver  43  and the map data, the overall control unit  52  calculates the travel route to the destination and makes the vehicle  30  travel along the travel route. The destination is sent from the management server  20 . The destination may be designated by the user through a display (not shown) inside the vehicle cabin  31 . 
     When the vehicle speed SP is lower than a specified vehicle speed while the vehicle  30  is traveling, the overall control unit  52  controls the alarm  33  such that the alarm  33  emits a warning sound. The specified vehicle speed is predetermined as a vehicle speed SP at which a traveling sound, such as road noise generated by tires, is relatively small and pedestrians need to be alerted to the presence of the host vehicle. The specified vehicle speed is, for example, 20 km/h. The overall control unit  52  sets a warning sound emission flag that is a flag indicating whether a warning sound is being emitted from the alarm  33 . When a warning sound is being emitted from the alarm  33 , the overall control unit  52  turns the warning sound emission flag on. When a warning sound is not being emitted the alarm  33 , the overall control unit  52  turns the warning sound emission flag off. 
     The overall control unit  52  activates the turn signals, the hazard flashers, the wipers, the air conditioner, and the power windows as necessary. For example, when the vehicle  30  turns right or left or changes the course while traveling, the overall control unit  52  activates the turn signal. The overall control unit  52  sets an activation flag that is a flag indicating the activation state of the turn signal. When the turn signal has been activated, the overall control unit  52  turns the activation flag of the turn signal on. When the turn signal has not been activated, the overall control unit  52  turns the activation flag of the turn signal off. Also for the other devices M than the turn signals, the overall control unit  52  sets for each device M an activation flag indicating the activation state of the device M. The activation flag for the power windows does not only indicate on and off states but also allows recognition of three states: a state where the window is opening or closing, a state where the window is closed, and a state where the window is open. 
     The control device  50  has a diagnosis unit  54  that diagnoses an abnormality of various parts of the vehicle  30 . The diagnosis unit  54  constitutes a diagnosis device. The diagnosis unit  54  can execute a diagnosis process for diagnosing an abnormality of the dashboard panel  35 . The diagnosis unit  54  performs an acquisition process and a determination process as part of the diagnosis process. The diagnosis unit  54  performs the acquisition process and the determination process while the vehicle  30  is traveling and while the vehicle  30  is stationary. 
     In the acquisition process executed while the vehicle  30  is traveling, when the alarm  33  emits a warning sound, the diagnosis unit  54  acquires detected warning sound data that is data about the sound pressure level L detected by the microphone  36  at a timing when the warning sound is emitted. In the determination process executed while the vehicle  30  is traveling, the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality by comparing the detected warning sound data with reference warning sound data. Specifically, when the difference in sound pressure level L between the detected warning sound data and the reference warning sound data is not smaller than a specified warning sound value, the diagnosis unit  54  determines that the dashboard panel  35  has an abnormality. The diagnosis unit  54  stores the reference warning sound data and the specified warning sound value in advance. The reference warning sound data and the specified warning sound value will be described later. 
     In the acquisition process executed while the vehicle  30  is stationary, when the horn  34  emits a honk, the diagnosis unit  54  acquires detected honk data that is data about the sound pressure level L detected by the microphone  36  at the timing when the honk is emitted. In the determination process executed while the vehicle  30  is stationary, the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality by comparing the detected honk data with reference honk data. Specifically, when the difference in sound pressure level L between the detected honk data and the reference honk data is not smaller than a specified honk value, the diagnosis unit  54  determines that the dashboard panel  35  has an abnormality. The diagnosis unit  54  stores the reference honk data and the specified honk value in advance. The reference honk data and the specified honk value will be described later. The diagnosis unit  54  performs the acquisition process and the determination process while the vehicle is standing still in the vehicle base. It is preferable that the vehicle base be an area where a honk emitted is not perceived as noise by neighbors. 
     Details of Diagnosis Process 
     The diagnosis unit  54  repeatedly executes the diagnosis process while the main system is running. The diagnosis unit  54  uses a stationary execution flag in part of a process performed in the diagnosis process. The stationary execution flag is a flag indicating completion of execution of the determination process executed while the vehicle is stationary. When the main system is shut down, the stationary execution flag is reset to off Therefore, at the time when the main system is started, the stationary execution flag is off. 
     The diagnosis unit  54  starts the diagnosis process when the main system is started. As shown in  FIG. 3 , the diagnosis unit  54  starts the diagnosis process by executing the process of step S 110 . In step S 110 , the diagnosis unit  54  determines whether diagnostic prerequisites are met. The diagnostic prerequisites have the following three items: 
     (i) The various devices M are not operating. 
     (ii) The windows are closed. 
     (iii) No occupant is present in the vehicle. 
     Based on the activation flags of the devices M, the diagnosis unit  54  determines whether the items (i) and (ii) are met. To determine whether the item (iii) is met, the diagnosis unit  54  acquires the latest values of the seat pressures W that the control device  50  receives from the pressure sensors  41 . The diagnosis unit  54  compares each of the acquired seat pressures W with a specified pressure. The diagnosis unit  54  stores the specified pressure in advance. The specified pressure is determined, for example, by experiment, as a minimum value of the pressure applied to the seat  40  when an occupant sits on the seat  40 . When each seat pressure W is not lower than the specified pressure, the diagnosis unit  54  determines that an occupant is present in the vehicle, and when each seat pressure W is lower than the specified pressure, the diagnosis unit  54  determines that no occupant is present in the vehicle. If there is even one item among the three items of the diagnostic prerequisites that is not met, the diagnosis unit  54  determines that the diagnostic prerequisites are not met (step S 110 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  executes the process of step S 110  again. 
     When all the three items are met in step S 110 , the diagnosis unit  54  determines that the diagnostic prerequisites are met (step S 110 : YES). In this case, the diagnosis unit  54  moves the process to step S 120 . 
     In step S 120 , the diagnosis unit  54  determines whether the vehicle  30  is traveling. To execute the process of step S 120 , the diagnosis unit  54  acquires the latest value of the vehicle speed SP that the control device  50  receives from the vehicle speed sensor  42 . Then, the diagnosis unit  54  determines whether the vehicle speed SP is higher than zero. When the vehicle speed SP is zero, the diagnosis unit  54  determines that the vehicle  30  is stationary (step S 120 : NO). In this case, the diagnosis unit  54  moves the process to step S 210 . 
     In step S 210 , the diagnosis unit  54  determines whether the vehicle  30  is located in the vehicle base. To execute the process of step S 210 , the diagnosis unit  54  receives the latest value of the current position coordinate G that the control device  50  receives from the GPS receiver  43 . Then, the diagnosis unit  54  determines whether the current position coordinate G of the vehicle  30  is inside the area of the vehicle base in the map data. When the current position coordinate G of the vehicle  30  is outside the area of the vehicle base, the diagnosis unit  54  determines that the vehicle  30  is not located in the vehicle base (step S 210 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  executes the process of step S 110  again. 
     When the current position coordinate G of the vehicle  30  is inside the area of the vehicle base in step S 210 , the diagnosis unit  54  determines that the vehicle  30  is located in the vehicle base (step S 210 : YES). In this case, the diagnosis unit  54  moves the process to step S 220 . 
     In step S 220 , the diagnosis unit  54  determines whether the determination process executed while the vehicle  30  is stationary is yet to be executed. The diagnosis unit  54  makes this determination based on the stationary execution flag. When the stationary execution flag is on, the diagnosis unit  54  determines that the determination process executed while the vehicle  30  is stationary has been executed (step S 220 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  executes the process of step S 110  again. 
     When the stationary execution flag is off in step S 220 , the diagnosis unit  54  determines that the determination process executed while the vehicle  30  is stationary is yet to be executed (step S 220 : YES). In this case, the diagnosis unit  54  moves the process to step S 230 . 
     In step S 230 , the diagnosis unit  54  switches the stationary execution flag to on. As described above, the stationary execution flag is reset to off when the main system is shut down. After switching the stationary execution flag to on, the diagnosis unit  54  moves the process to step S 240 . 
     In step S 240 , the diagnosis unit  54  starts to output, to the overall control unit  52 , a honk requesting signal that is a signal requesting emission of a honk by the horn  34 . Then, the diagnosis unit  54  moves the process to step S 250 . Upon receiving the honk requesting signal, the overall control unit  52  controls the horn  34  such that the horn  34  emits a honk. 
     In step S 250 , the diagnosis unit  54  acquires detected honk data. Specifically, the diagnosis unit  54  acquires the latest value of the sound pressure level L that the control device  50  receives from the microphone  36 . Then, the diagnosis unit  54  handles the acquired sound pressure level L as the detected honk data. After acquiring the detected honk data, the diagnosis unit  54  moves the process to step S 260 . The process of step S 250  is the acquisition process. 
     In step S 260 , the diagnosis unit  54  stops outputting the honk requesting signal. Then, the diagnosis unit  54  moves the process to step S 270 . When the output of the honk requesting signal is stopped, the overall control unit  52  controls the horn  34  such that the horn  34  stops emitting a honk. 
     In step S 270 , the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality using the detected honk data. To determine whether the dashboard panel  35  has an abnormality, the diagnosis unit  54  first calculates a differential honk value that is obtained by subtracting the reference honk data from the detected honk data. As described above, the diagnosis unit  54  stores the reference honk data in advance. The reference honk data is a sound pressure level L that is detected by the microphone  36  when it is assumed that the horn  34  has emitted a honk under the condition that the diagnostic prerequisites are met and in a state where the dashboard panel  35  has no abnormality. For example, a value calculated as follows can be used as the reference honk data. When the vehicle  30  to be diagnosed is in a brand-new state, the following experiment is repeated multiple times. This experiment involves emitting a honk by the horn  34  in a situation where the diagnostic prerequisites are met, and acquiring the sound pressure level L detected by the microphone  36  at that time. An average value of a plurality of sound pressure levels L obtained by repeating this experiment multiple times is used as the reference honk data. 
     After calculating the differential honk value, the diagnosis unit  54  compares the differential honk value and the specified honk value. As described above, the diagnosis unit  54  stores the specified honk value in advance. The specified honk value is determined, for example, by experiment, as a value such that one can see that there is a difference in sound pressure level L between the detected honk data and the reference honk data that cannot occur if the dashboard panel  35  is normal. The specified honk value can be determined, for example, with a detection error of the microphone  36  taken into account. 
     When the differential honk value is smaller than the specified honk value, the diagnosis unit  54  determines the dashboard panel  35  has no abnormality (step S 270 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  executes the process of step S 110  again. 
     When the differential honk value is not smaller than the specified honk value, the diagnosis unit  54  determines that the dashboard panel  35  has an abnormality (step S 270 : YES). In this case, the diagnosis unit  54  moves the process to step S 300 . The process of step S 270  is the determination process. 
     In step S 300 , the diagnosis unit  54  generates abnormality information including information to the effect that the dashboard panel  35  has an abnormality and the individual identification information on the host vehicle. Then, the diagnosis unit  54  sends the abnormality information to the management server  20 . Thereafter, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process and executes the process of step S 110  again. Upon receiving the abnormality information, the management server  20  finds out the corresponding vehicle  30  based on the individual identification information included in the abnormality information and stores an event that the dashboard panel  35  of the corresponding vehicle  30  has been determined to have an abnormality. The information stored by the management server  20  is read by a manager of the management server  20  and used to learn the condition of the vehicle  30 . 
     In step S 120 , when the vehicle speed SP is higher than zero, the diagnosis unit  54  determines that the vehicle  30  is traveling (step S 120 : YES). In this case, the diagnosis unit  54  moves the process to step S 130 . 
     In step S 130 , the diagnosis unit  54  determines whether the alarm  33  is emitting a warning sound. The diagnosis unit  54  makes this determination based on the warning sound emission flag. When the warning sound emission flag is off, the diagnosis unit  54  determines that the alarm  33  is not emitting a warning sound (step S 130 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  performs the process of step S 110  again. 
     When the warning sound emission flag is on in step S 130 , the diagnosis unit  54  determines that the alarm  33  is emitting a warning sound (step S 130 : YES). In this case, the diagnosis unit  54  moves the process to step S 140 . 
     In step S 140 , the diagnosis unit  54  acquires detected warning sound data. Specifically, the diagnosis unit  54  acquires the latest value of the sound pressure level L that the control device  50  receives from the microphone  36 . Then, the diagnosis unit  54  handles the acquired sound pressure level L as the detected warning sound data. After acquiring the detected warning sound data, the diagnosis unit  54  moves the process to step S 150 . The process of step S 140  is the acquisition process. 
     In step S 150 , the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality using the detected warning sound data. To determine whether the dashboard panel  35  has an abnormality, the diagnosis unit  54  first calculates a differential warning sound value that is obtained by subtracting the reference warning sound data from the detected warning sound data. As described above, the diagnosis unit  54  stores the reference warning sound data in advance. The reference warning sound data is a sound pressure level L that is detected by the microphone  36  when it is assumed that the alarm  33  has emitted a warning sound under the condition that the diagnostic prerequisites are met and in a state where the dashboard panel  35  has no abnormality. A value calculated by applying the same method as used for the reference honk data to the warning sound can be used as the reference warning sound data. 
     After calculating the differential warning sound value, the diagnosis unit  54  compares the differential warning sound value and the specified warning sound value. As described above, the diagnosis unit  54  stores the specified warning sound value in advance. The specified warning sound value is determined from the same perspective as the specified honk value. 
     When the differential warning sound value is smaller than the specified warning sound value, the diagnosis unit  54  determines that the dashboard panel  35  has no abnormality (step S 150 : NO). In this case, the diagnosis unit  54  temporarily ends the series of processes of the diagnosis process. Then, the diagnosis unit  54  executes the process of step S 110  again. 
     When the differential warning sound value is not smaller than the specified warning sound value in step S 150 , the diagnosis unit  54  determines that the dashboard panel  35  has an abnormality (step S 150 : YES). In this case, the diagnosis unit  54  moves the process to step S 300 . The contents of the process of step S 300  are as already described. The process of step S 150  is the determination process. 
     Workings of First Embodiment 
     The acoustic insulator of the dashboard panel  35  can crack due to deterioration. In this case, a sound that the alarm  33  or the horn  34  emits inside the motor compartment  32  reaches into the vehicle cabin  31  more easily. Further, the mounting part that integrates the dashboard panel main body and the acoustic insulator can come off. In this case, the through-holes in the dashboard panel main body and the acoustic insulator in which the mounting part has been mounted are opened. A sound that the alarm  33  or the horn  34  emits inside the motor compartment  32  reaches into the vehicle cabin  31  more easily through these through-holes. Given this cause-and-effect relationship, an abnormality of the dashboard panel  35  can be diagnosed by analyzing the sound pressure level L detected by the microphone  36  inside the vehicle cabin  31  when the alarm  33  or the horn  34  emits a sound inside the motor compartment  32 . 
     When diagnosing an abnormality of the dashboard panel  35  using a sound emitted by the alarm  33  or the horn  34  inside the motor compartment  32 , the accuracy of the diagnosis decreases if the microphone  36  detects a sound pressure level L of a sound including a sound other than a warning sound or a honk when the alarm  33  or the horn  34  has emitted the sound. Examples of other sounds that the microphone  36  can detect include the operating sound of the various devices M when they are operating, sounds outside the vehicle cabin  31  when the window is open, and voices of occupants when they are present in the vehicle. For this reason, in the diagnosis process, the diagnostic prerequisites are provided for acquiring the detected warning sound data or the detected honk data. 
     In the diagnosis process, on the condition that the diagnostic prerequisites are met, the diagnosis unit  54  acquires the detected warning sound data when the alarm  33  emits a warning sound while the vehicle  30  is traveling. Further, on the condition that the diagnostic prerequisites are met, the diagnosis unit  54  acquires the detected honk data when the horn  34  emits a honk in a state where the vehicle  30  is standing still in the vehicle base. Using these detected warning sound data and detected honk data, the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality. 
     Effects of First Embodiment 
     (1-1) Since the dashboard panel  35  is disposed at such a position that the external appearance thereof is hardly visible to an occupant, and in addition, the dashboard panel  35  is not a part that moves or emits a sound, even when an abnormality such as deterioration of the acoustic insulator occurs, the user hardly notices the abnormality. Moreover, in the shared use system  10 , users are likely to use a different vehicle  30  each time. This makes it even more difficult for users to notice an abnormality of the dashboard panel  35  of a certain vehicle  30 . 
     In this embodiment, when the alarm  33  or the horn  34  emits a sound, the diagnosis unit  54  acquires the sound pressure level L detected by the microphone  36  at the timing of emission of the sound as the detected warning sound data or the detected honk data. Therefore, even when the user has not felt an abnormality of the dashboard panel  35 , the diagnosis unit  54  can acquire the data required for diagnosing the dashboard panel  35 . After acquiring these pieces of data, the diagnosis unit  54  determines whether the dashboard panel  35  has an abnormality using these pieces of data. Thus, the diagnosis unit  54  can diagnose an abnormality of the dashboard panel  35  regardless of whether the user has felt an abnormality of the dashboard panel  35 . 
     (1-2) As described above in connection with the workings, when the dashboard panel  35  has an abnormality, a sound emitted by the alarm  33  or the horn  34  inside the motor compartment  32  reaches into the vehicle cabin  31  more easily. In this case, the microphone  36  is likely to detect a higher sound pressure level L. Thus, whether the dashboard panel  35  has an abnormality can be determined appropriately by determining whether the detected warning sound data is high compared with the reference warning sound data or whether the detected honk data is high compared with the reference honk data as in this embodiment. 
     (1-3) As described above in connection with the workings, in this embodiment, the detected warning sound data or the detected honk data is acquired only in a situation whether the diagnostic prerequisites are met. Thus, data from which other sounds than the sound required for diagnosing an abnormality of the dashboard panel  35  are excluded can be acquired. Using such data can achieve high diagnostic accuracy. 
     (1-4) In this embodiment, a warning sound emitted by the alarm  33  is used to diagnose an abnormality of the dashboard panel  35 . The alarm  33  is an existing device that is commonly installed in electric vehicles. Using a sound emitted by such an existing device can eliminate the need for adding a sound source to the vehicle  30  just for diagnostic purposes. A warning sound of the alarm  33  is emitted independently of whether the user has felt some kind of abnormality. Therefore, an abnormality of the dashboard panel  35  can be diagnosed by acquiring the detected warning sound data without the user performing any operation. 
     (1-5) In this embodiment, a honk emitted by the horn  34  is used to diagnose an abnormality of the dashboard panel  35 . The horn  34  is an existing device that is commonly installed in automobiles. Using a sound emitted by such an existing device can eliminate the need for adding a sound source to the vehicle  30  just for diagnostic purposes. Here, opportunities for sounding the horn while the vehicle  30  is traveling are limited. In this embodiment, therefore, the detected honk data is acquired by emitting a honk in a specific place, namely the vehicle base. This can increase the opportunities to diagnose the dashboard panel  35  without inconsiderately emitting a honk. When the horn  34  emits a honk, it emits a honk under the control of the diagnosis unit  54  and not in response to the user&#39;s operation. Thus, an abnormality of the dashboard panel  35  can be diagnosed by acquiring the detected honk data without the user performing any operation. 
     (1-6) In this embodiment, the acquisition process and the determination process are performed in the control device  50  of the vehicle  30 . Thus, there is no need to separately provide a processing device dedicated to diagnosing the dashboard panel  35 . There is also no need to send and receive information required for diagnosis between such a processing device and the vehicle  30 . Thus, the burden of processes corresponding to sending and receiving such information does not arise. 
     Second Embodiment 
     A second embodiment of the vehicle diagnosis system will be described below with reference to  FIG. 4  and  FIG. 5 . The second embodiment is different from the first embodiment only in the configurations of the management server  20  and the control device  50  of the vehicle  30 . In the following, these differences from the first embodiment will be mainly described, while description of contents overlapping with the first embodiment will be simplified or omitted. In  FIG. 4 , among the components of the shared use system  10  described in  FIG. 1 , only the management server  20  and one vehicle  30  are shown. Further, in  FIG. 4 , only some of the members of the vehicle  30  shown in  FIG. 2  are shown while the other members are omitted. 
     As shown in  FIG. 4 , the management server  20  has a server diagnosis unit  22  that diagnoses an abnormality of the dashboard panel  35 . The server diagnosis unit  22  constitutes a diagnosis device. The server diagnosis unit  22  can execute a server-conducted diagnosis process for diagnosing an abnormality of the dashboard panel  35 . The server diagnosis unit  22  performs an acquisition process and a determination process. In the acquisition process, the server diagnosis unit  22  acquires detected sound data from a vehicle to be diagnosed that is the vehicle  30  of which the dashboard panel  35  is to be diagnosed. In the acquisition process, the server diagnosis unit  22  acquires vehicle type information on the vehicle to be diagnosed from the vehicle to be diagnosed. In the determination process, the server diagnosis unit  22  determines whether the dashboard panel  35  has an abnormality by comparing the detected sound data with reference sound data as in the above embodiment. The server diagnosis unit  22  stores pieces of reference warning sound data for the respective vehicle types. The reference warning sound data is calculated for each vehicle type by the method described in the first embodiment. Further, the server diagnosis unit  22  stores specified warning sound values for the respective vehicle types. The specified warning sound values are determined from the same perspective as in the above embodiment, for example, with the type of the microphone  36  of each vehicle type taken into account. 
     The control device  50  of the vehicle  30  has a diagnosis assistance unit  56  instead of the diagnosis unit described in the first embodiment. The diagnosis assistance unit  56  can execute a diagnosis assistance process for sending information required for diagnosing an abnormality of the dashboard panel  35  to the management server  20 . When the main system is started, the diagnosis assistance unit  56  starts the diagnosis assistance process. 
     As shown in  FIG. 5 , the diagnosis assistance unit  56  starts the diagnosis assistance process by executing the process of step S 510 . In step S 510 , the diagnosis assistance unit  56  determines whether the diagnostic prerequisites are met. The contents of the process of step S 510  are the same as the contents of the process of step S 110  of the first embodiment. Therefore, description of the contents of the process of step S 510  will be omitted. When the diagnostic prerequisites are not met, the diagnosis assistance unit  56  executes the process of step S 510  again (step S 510 : NO). The diagnosis assistance unit  56  repeats the process of step S 510  until the diagnostic prerequisites are met. When the diagnostic prerequisites are met, the diagnosis assistance unit  56  moves the process to step S 520  (step S 510 : YES). 
     In step S 520 , the diagnosis assistance unit  56  determines whether the alarm  33  is emitting a warning sound. The contents of the process of step S 520  are the same as the contents of the process of step S 130  in the first embodiment. Therefore, description of the contents of the process of step S 520  will be omitted. When the alarm  33  is not emitting a warning sound, the diagnosis assistance unit  56  returns to the process of step S 510  (step S 520 : NO). The diagnosis assistance unit  56  repeats the processes of step S 510  and step S 520  until the alarm  33  emits a warning sound in a situation where the diagnostic prerequisites are met. When the alarm  33  emits a warning sound in a situation where the diagnostic prerequisites are met, the diagnosis assistance unit  56  moves the process to step S 530  (step S 520 : YES). 
     In step S 530 , the diagnosis assistance unit  56  acquires the latest value of the sound pressure level L that the control device  50  receives from the microphone  36 . Then, the diagnosis assistance unit  56  generates information for diagnosis including the acquired sound pressure level L and the individual identification information on the host vehicle. Then, the diagnosis assistance unit  56  sends the formation for diagnosis to the management server  20 . After executing the process of step S 530 , the diagnosis assistance unit  56  ends the series of processes of the diagnosis assistance process. Depending on the determinations in step S 510  and step S 520 , the main system may be shut down before the series of processes of the diagnosis assistance process ends. 
     Upon receiving the information for diagnosis sent from the diagnosis assistance unit  56 , the server diagnosis unit  22  of the management server  20  starts the server-conducted diagnosis process. The server diagnosis unit  22  starts the server-conducted diagnosis process by executing the process of step S 610 . In step S 610 , the server diagnosis unit  22  acquires the detected warning sound data and the vehicle type information. Specifically, the server diagnosis unit  22  reads the sound pressure level L from the received information for diagnosis. The server diagnosis unit  22  handles the read value as the detected warning sound data. The server diagnosis unit  22  reads the vehicle type of the vehicle to be diagnosed from the received information for diagnosis. After executing these processes, the server diagnosis unit  22  moves the process to step S 620 . The process of step S 610  is the acquisition process. 
     In step S 620 , the server diagnosis unit  22  determines whether the dashboard panel  35  has an abnormality. To determine whether the dashboard panel  35  has an abnormality, the server diagnosis unit  22  first selects the piece of reference warning sound data corresponding to the vehicle type of the vehicle to be diagnosed from the pieces of reference warning sound data for the respective vehicle types. Then, the server diagnosis unit  22  calculates a differential warning sound value that is obtained by subtracting the selected reference warning sound data from the detected warning sound data acquired in step S 610 . 
     After calculating the differential warning sound value, the server diagnosis unit  22  compares the differential warning sound value and the specified warning sound value. To make this comparison, the server diagnosis unit  22  selects the specified warning sound value corresponding to the vehicle type of the vehicle to be diagnosed from the specified warning sound values of the respective vehicle types. Then, the server diagnosis unit  22  compares the selected differential warning sound value and specified warning sound value. When the differential warning sound value is smaller than the specified warning sound value, the server diagnosis unit  22  determines that the dashboard panel  35  has no abnormality (step S 620 : NO). In this case, the server diagnosis unit  22  ends the series of processes of the server-conducted diagnosis process. 
     When the differential warning sound value is not smaller than the specified warning sound value in step S 620 , the server diagnosis unit  22  determines that the dashboard panel  35  has an abnormality (step S 620 : YES). In this case, the server diagnosis unit  22  moves the process to step S 630 . The process of step S 620  is the determination process. 
     In step S 630 , the server diagnosis unit  22  stores an event that the dashboard panel  35  of the vehicle to be diagnosed has been determined to have an abnormality. Thereafter, the server diagnosis unit  22  ends the series of processes of the server-conducted diagnosis process. The information on the abnormality of the dashboard panel  35  is read by the manager of the management server  20  and used to learn the condition of the vehicle  30 . 
     Workings of Second Embodiment 
     On the condition that the diagnostic prerequisites are met, the diagnosis assistance unit  56  of the vehicle  30  sends information for diagnosis to the management server  20  when the alarm  33  emits a warning sound while the vehicle  30  is traveling. Upon receiving the information for diagnosis, the server diagnosis unit  22  of the management server  20  acquires the detected warning sound data and determines whether the dashboard panel  35  has an abnormality. 
     Effects of Second Embodiment 
     This embodiment can produce the following effect (2-1) in addition to the same effects as (1-1) to (1-4) described above. 
     (2-1) In this embodiment, the vehicles  30  are diagnosed by a single diagnosis device. When this configuration is adopted, high determination accuracy is achieved by using the pieces of reference warning sound data and the specified warning sound values for the respective vehicle types. Here, it may become necessary to update, for example, the specified warning sound values for the respective vehicle types. In the configuration in which the diagnosis device is provided in the control device  50  of each vehicle  30  as in the first embodiment, this update involves updating each of the specified warning sound values while checking the vehicle type for each control device  50  of the vehicle  30 , which takes time and effort. In this respect, if the configuration in which a single diagnosis device is shared among the vehicles  30  is adopted as in this embodiment, the process of changing the information needs to be performed on only the management server  20  that is the single diagnosis device, and the specified warning sound values of only the vehicles of the corresponding vehicle type need to be changed in that process. The updating process is thereby significantly simplified. Thus, this embodiment can simplify the management of the diagnosis device. 
     Modified Examples 
     The first embodiment and the second embodiment can be implemented with the following changes made thereto. The first embodiment, the second embodiment, and the following modified examples can be implemented in combinations within such a range that no technical inconsistency arises.
         Regarding the first embodiment, an abnormality of the dashboard panel  35  may be diagnosed using only one of a warning sound and a honk. Regarding the second embodiment, an abnormality of the dashboard panel  35  may be diagnosed using a honk instead of or in addition to a warning sound. Regarding the second embodiment, when diagnosing an abnormality of the dashboard panel  35  using a honk, the honk should be emitted when the vehicle  30  is parked in the vehicle base as in the first embodiment. Then, the sound pressure level L detected by the microphone  36  when the honk is emitted should be sent to the management server  20  as the information for diagnosis.   The area where a honk is emitted is not limited to the vehicle base. The area where a honk is emitted may be a point where a “sound horn” sign is provided. It is preferable that the area where a honk is emitted be determined with noise caused to neighbors taken into account.   The dashboard panel  35  may be diagnosed by emitting a honk while the vehicle  30  is traveling. —The contents of the diagnostic prerequisites are not limited to those shown in the first embodiment and the second embodiment. The contents and the number of the items of the diagnostic prerequisites are not limited as long as appropriate data for diagnosing an abnormality of the dashboard panel  35  can be obtained.   The contents of the diagnostic prerequisites in the first embodiment and the second embodiment are intended to exclude other sounds than the sound to be detected. However, an item “There is a certain sound.” may be included in the diagnostic prerequisites. For example, an item “An occupant is present in the vehicle.” may be included. Further, for example, an item “There is the operating sound of a certain device M.” may be included. Also when diagnostic prerequisites including these items are adopted, an appropriate diagnosis can be made by determining the reference warning sound data and the reference honk data based on the assumption of a situation where these diagnostic prerequisites are met.   The reference warning sound data is not limited to that shown in the first embodiment and the second embodiment. The reference warning sound data may be any data that allows appropriate determination in the determination process. A sound when the dashboard panel  35  has an abnormality may be used as the reference warning sound data. Then, the dashboard panel  35  may be determined to have an abnormality when, for example, the detected sound data and the reference warning sound data are equivalent. As will be described in the subsequent modified example, depending on the determination method used in the determination process, an instantaneous value of the sound pressure level L may be handled as the reference warning sound data, instead of calculating the reference warning sound data by statistically processing the sound pressure level L as in the first embodiment. The same applies to the reference honk data.   The determination method used in the determination process and the aspect of acquisition of the detected sound data in the acquisition process are not limited to those shown in the first embodiment and the second embodiment. The determination method used in the determination process may be any technique that can appropriately determine whether the dashboard panel  35  has an abnormality. In the acquisition process, at least the data required for the determination process should be acquired. In the determination process, for example, a rate at which the sound pressure level L decays after the warning sound has been emitted from the alarm  33  may be used as an index in making a determination. In this case, in the acquisition process, the sound pressure levels L detected by the microphone  36  are consecutively acquired as the detected warning sound data, until a predetermined specified period has elapsed from the timing when the alarm  33  has emitted the warning sound. Thus, time-series detected warning sound data is acquired. This time-series data is acquired in a situation where the diagnostic prerequisites are continuously met. In the determination process, a detected rate of decay that is a rate of decay relating to the detected warning sound data is calculated using this time-series data. For example, the detected rate of decay is calculated by dividing, by the specified period, a value obtained by subtracting the final value of the time-series data from the first value thereof. Then, the calculated detected rate of decay is compared with a reference rate of decay, and when the former is lower than the latter by not less than a specified rate, it is determined that the dashboard panel  35  has an abnormality. Thus, when the value obtained by subtracting the detected rate of decay form the reference rate of decay is not lower than the specified rate, it is determined that the dashboard panel  35  has an abnormality.       

     The reference rate of decay is a rate at which the sound pressure level L decays after the alarm  33  has emitted the warning sound when it is assumed that the alarm  33  has emitted the warning sound in a state where the dashboard panel  35  has no abnormality. For example, the reference rate of decay is calculated in advance as follows. First, when the vehicle  30  to be diagnosed is in a brand-new state, the sound pressure levels L that the microphone  36  detects are consecutively acquired as the reference warning sound data until the specified period has elapsed from when the alarm  33  has emitted the warning sound. Thus, time-series reference warning sound data is acquired. As with when the detected warning sound data is acquired, the time-series reference warning sound data is acquired in a situation where the diagnostic prerequisites are continuously met. After the time-series reference warning sound data is acquired, the rate of decay of the sound pressure level L is calculated based on this time-series data. The rate of decay relating to pieces of time-series data is calculated using such a calculation method, and an average value of a plurality of rates of decay is used as the reference rate of decay. The specified rate used in the determination process should be determined as a value such that one can see that there is a difference in rate of decay between the detected rate of decay and the reference rate of decay that cannot occur if the dashboard panel  35  is normal. The specified period should be determined as a period having a length appropriate for calculating the rate of decay of the sound pressure level L. 
     When the acoustic insulator deteriorates or the mounting part comes off in the dashboard panel  35 , a warning sound emitted by the alarm  33  may decay less inside the vehicle cabin  31 . In this case, the sound pressure level L detected by the microphone  36  is likely to have a lower rate of decay. By determining an abnormality of the dashboard panel  35  using this characteristic, the above-described determination method can appropriately determine whether there is an abnormality.
         In the determination process, a power spectrum that is obtained by conducting a frequency analysis on time-series data of the sound pressure level L in a period when the alarm  33  is emitting a warning sound may be used. The power spectrum is a graph showing the energy of the sound pressure level L by unit frequency. When a determination is made using the power spectrum, in the acquisition process, the sound pressure levels L detected by the microphone  36  are consecutively acquired as detected warning sound data for a certain period in which the alarm  33  is emitting a warning sound. Thus, time-series detected warning sound data is acquired. In the determination process, a detected power spectrum that is a power spectrum based on this time-series data is compared with a reference power spectrum. When, at a certain frequency, the energy of the sound pressure level L in the detected power spectrum is higher than the energy of the sound pressure level L in the reference power spectrum by not less than specified energy, it is determined that the dashboard panel  35  has an abnormality.       

     The reference power spectrum is a power spectrum relating to time-series data of the sound pressure level L that is detected by the microphone  36  when it is assumed that the alarm  33  has emitted a warning sound over a certain period in a state where the dashboard panel  35  has no abnormality. As in the above-described modified example involving the rate of decay, the reference power spectrum should be calculated, for example, by acquiring the sound pressure level L when the vehicle  30  to be diagnosed is in a brand-new state as reference warning sound data. The specified energy should be determined as a value such that one can see that there is a difference in energy between the detected power spectrum and the reference power spectrum that cannot occur if the dashboard panel  35  is normal. 
     When a determination is made using the power spectrum, sounds emitted by a plurality of sound sources can be isolated from one another by the frequency. Therefore, this method is preferable in determining whether there is an abnormality while excluding the influence of other sounds than the sound to be detected. Further, when the power spectrum is used, since sound sources can be isolated from one another, the diagnostic prerequisites are not necessarily required for acquiring the detected sound data in the acquisition process. This is preferable in increasing the opportunities to diagnose the dashboard panel  35 .
         As mentioned in the above-described modified example, setting the diagnostic prerequisites is not essential.   The vehicle  30  is not limited to a vehicle that is capable of only autonomous driving. That is, the vehicle  30  may be configured to be able to switch between autonomous driving and driving by the driver&#39;s operation, or may be configured to be capable of only driving by the driver&#39;s operation.   When the vehicle  30  is capable of driving by the driver&#39;s operation, an abnormality of the dashboard panel  35  may be diagnosed when the horn  34  emits a honk in accordance with the driver&#39;s operation.   The components of the vehicle  30  are not limited to those shown in the above embodiments. For example, in addition to the motor-generator  37 , the vehicle  30  may have an internal combustion engine as a drive source of the vehicle  30  inside the motor compartment  32 . When the vehicle  30  has an internal combustion engine, the motor compartment  32  may be referred to as an engine compartment.   The sound source used to diagnose the dashboard panel  35  is not limited to the alarm  33  or the horn  34 . If a sound source that is located on the opposite side of the dashboard panel  35  from the vehicle cabin  31  is used, an abnormality of the dashboard panel  35  can be appropriately diagnosed. For example, when the vehicle  30  has an internal combustion engine as in the above modified example, the internal combustion engine may be used as a sound source. An abnormality of the dashboard panel  35  may be diagnosed using the operating sound of the internal combustion engine.   At least one of the sound pressure and the frequency of a sound that is emitted by the sound source used to diagnose the dashboard panel  35  should be predetermined. For a sound emitted by the sound source, an appropriate diagnosis method should be used according to the specified element of the sound. For example, when the sound pressure of a sound emitted by the sound source is specified, as in the above embodiments, the diagnosis method using the magnitude of the sound pressure can be used to appropriately diagnose an abnormality of the dashboard panel  35 . Further, for example, when the frequency of a sound emitted by the sound source is specified, the diagnosis method using the rate of decay of the sound pressure as described in the above modified example can be used to appropriately diagnose an abnormality of the dashboard panel  35 .   In the case where a sound source separate from the alarm  33  and the horn  34  is provided as a sound source used to diagnose the dashboard panel  35 , the frequency of a sound emitted by that sound source is not limited to a frequency in the audible range. Since the sound source in this case is not intended to have its sound perceived by others, a sound at a frequency outside the audible range does not pose any difficulty in making a diagnosis.   The vehicle to be diagnosed is not limited to a vehicle belonging to the shared use system  10 . For example, the vehicle to be diagnosed may also be a private vehicle.   The part to be diagnosed is not limited to the dashboard panel  35 . The part to be diagnosed may be any part that separates the inside and the outside of the vehicle cabin  31 . If the sound source is located on the opposite side of the part to be diagnosed from the vehicle cabin  31 , an appropriate diagnosis can be made in the same manner as when the dashboard panel  35  is diagnosed. For example, the part to be diagnosed may be a door of a vehicle. Further, for example, the part to be diagnosed may be the roof of a vehicle. When the vehicle is a vehicle that has a speaker mounted on its roof like a publicity vehicle, for example, this speaker can be used as a sound source. By using a sound emitted by the speaker, an abnormality of peripheral parts including the roof can be diagnosed.   The external device is not limited to the management server  20  of the shared use system  10 . The external device may be, for example, a processing device used in a vehicle maintenance shop.   The physical quantity detected by the microphone  36  is not limited to the sound pressure level L. The physical quantity detected by the microphone  36  may be a sound pressure itself. The physical quantity handled as the detected sound data in the acquisition process should be changed according to the physical quantity detected by the microphone  36 . Further, the physical quantity of the data used for diagnosis, such as the reference warning sound data and the specified warning sound value, should be changed according to the physical quantity handled as the detected sound data.