Abstract:
A brake monitoring system and method for a vehicle having multiple axles and a plurality of brake actuators and an engine control module, each brake actuator being associated with one of the axle. The system include sensors for measuring, in real-time, brake pressure and brake lining wear, and generating first and second signals. The first and second signals are received and stored in a chassis communications module. The chassis communications module detects fault condition of the brakes as a function of the first and/or second signals and for recording the fault condition, the fault condition being one of a brake monitor warning and a brake lining warning and provides an indication of status via warning lights.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application 61/147,029, filed Jan. 23, 2009, which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the brake monitoring system a motor vehicle, and more particularly, to a brake monitoring system which measures, records, and can transmit actual brake pressure in real time for the purpose of detecting fault conditions and performing diagnostics, on-board and/or off-board the motor vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to an improved brake monitoring system, particularly for use on vehicles such as a tractor and trailer combination. 
         [0004]    In the prior art, heavy duty trucks and other large vehicles are typically equipped with an air brake actuating system. The air brake actuating system applies air to a service chamber to move a diaphragm in a first direction. A push rod typically moves with the diaphragm, and the push rod is connected to a linkage that actuates the vehicle brakes. An emergency chamber is generally also attached adjacent to the service chamber, and is operable to move the push rod in the event that the air system fails. To this end, a high strength power spring is typically incorporated into the emergency chamber to actuate the push rod when there is a failure in the system air line. This spring also typically actuates the push rod when the vehicle is parked. 
         [0005]    A brake actuator has a predetermined amount of available movement, or stroke, for the push rod. The amount of movement of the push rod required to fully actuate the brakes must be carefully monitored such that it is within the stroke of the brake actuator. The prior art has experienced situations wherein there has been an excessive amount of push rod movement for actuation of the brake system. This excessive required push rod movement can be created by any one of several factors. Typically, excessive movement is due to brake lining wear. As the brakes wear, more movement of the push rod is required to actuate the brakes. Further, as the linkages, connections, etc. between the members connecting the push rod to the brakes bend or become loose or excessively worn, additional push rod movement may be required to adequately stroke the brake. A combination of these several features may sometimes cause the amount of push rod movement required to actuate the brakes to approach the available push rod movement, or stroke, from the brake actuator. This is, of course, an undesirable situation. 
         [0006]    The prior art has attempted to monitor the amount of push rod movement during actuation of the brake, and provide some indication to an operator of when there is excessive push rod movement. The determination of when there is excessive push rod movement is dependent upon the designed stroke, or rated stroke, of the brake actuator. In addition, an apparatus known as a slack adjuster is typically placed between the push rod and the foundation brake. The slack adjuster is incrementally adjusted to compensate for slack in the braking system and to decrease the required push rod movement. Automatic slack adjusters are now available which automatically adjust the foundation brake system. 
         [0007]    Electronic indicator systems have been proposed. However, there are several obstacles to overcome. First, powering and monitoring electronic indicators on each of the brake actuators on an 18-wheel vehicle is costly. The cost in wiring alone for the vehicle exceeds the cost of all the electronic indicators and monitoring equipment combined. Further, the hostile environment in which the brake actuators are mounted can damage the wires connecting the brake actuators to a controller. 
         [0008]    Further, there are numerous configurations for the tractors as well as the trailers. For example, the number of axles on tractors and trailers can vary. Each axle may include a spring brake actuator or just a service brake actuator. For efficiency, it would be desirable to have a single electronic controller which could be permanently programmed to recognize the specific configuration of the vehicle on which it is installed. 
         [0009]    One such system is disclosed in U.S. Pat. No. 6,501,375, issued Dec. 31, 2002 to Bob R. Weant, et al, which is hereby incorporated by reference. However, the Weant system does not take into account numerous advances in sensor and system technology. 
         [0010]    The present invention is aimed at one or more of the problems set forth above. 
       SUMMARY OF THE INVENTION 
       [0011]    In one aspect of the present invention, a brake monitoring system is provided. The brake monitoring system includes a chassis communications module, one or more e-stroke sensors, one or more brake lining wear sensors, and at least one pressure sensor. The sensors are electronically coupled to the chassis communications module which reads and stores the sensor data. The chassis communications module utilizes the sensor data to detect brake stroke (dragging, non-functioning, overstroke), brake stroke sensor or lining wear faults. The sensor and fault data may be relayed to an off-board diagnostics tool for further analysis/diagnostics. 
         [0012]    In one aspect of the present invention, real-time actual pressure sensor data is measured, transmitted, and optionally stored. 
         [0013]    In another aspect of the present invention, the brake monitoring system includes a diagnostic display tool to detect over-stroke conditions. 
         [0014]    In a still further aspect of the present invention, the chassis communications module and/or the diagnostic display tool may perform diagnostics as a function of the sensor data, including but not limited to, detecting the frequency and severity of panic stops, normal braking activity, etc. . . . 
         [0015]    In a first aspect of the present invention, a brake monitoring system for a vehicle having multiple axles and a plurality of brake actuators and an engine control module is provided. Each brake actuator is associated with one of the axles. The system includes a plurality of sensors, a plurality of brake lining wear sensors, a chassis communications module, and a diagnostic device. Each sensor is mounted in a respective actuator for sensing in real-time a parameter of the respective actuator and for generating a respective first signal. Each brake lining wear sensor is contained within each brake lining actuator and detects a brake wear parameter of the respective actuator and generating a respective second signal. The chassis communications module is coupled to the sensors and the brake lining wear sensors via a wire harness, receives the first and second signals and stores the first and second signals thereon. The chassis communications module detects a fault condition of one of the brakes as a function of the first and/or second signals and records the fault condition. The fault condition is one of a brake monitor warning and a brake lining warning. The chassis communications module has a plurality of warning lights. Each warning light corresponds to one of the fault conditions. The chassis communications module actuates a respective one of the warning lights in response to detecting the respective warning condition. The diagnostic device is coupled to the chassis communications control module via a datalink and receives the first and second signals and the fault conditions stored in the chassis communications control module and stores the first and second signals and the fault conditions on the diagnostic device. The fault condition may be indicative of a dragging brake condition. The chassis control module can then send a signal to the engine control module to throttle back the vehicle, or limit the speed of the vehicle and/or the RPM of the engine in response to detecting the dragging brake condition. 
         [0016]    In a second aspect of the present invention, a method for monitoring the brakes of a vehicle having multiple axles, a plurality of brake actuators, and an engine control module is provided. Each brake actuator being is associated with one of the axles. The method includes the steps of sensing, in real-time, a parameter of each actuator, using a sensor, and for generating a respective first signal and detecting a brake wear parameter of each actuator using a brake lining wear sensor, and generating a respective second signal. Each brake lining wear sensor is contained within the respective brake lining actuator. The method further includes the steps of receiving the first and second signals at a chassis communications module via a wire harness and storing the first and second signals thereon, detecting a fault condition of one of the brakes as a function of the first and/or second signals and for recording the fault condition. The fault condition is one of a brake monitor warning and a brake lining warning. The method also includes the steps of providing, on the chassis communications module a plurality of warning lights, actuating a respective one of the warning lights in response to detecting the respective warning condition, receiving the first and second signals and the fault conditions at a diagnostic device coupled to the chassis communications control module via a datalink, and storing the first and second signals and the fault conditions thereon. The fault condition may be indicative of a dragging brake condition. The method also includes the step of sending a signal to the engine control module to throttle back the vehicle, or limit the speed of the vehicle and/or the RPM of the engine in response to detecting the dragging brake condition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0018]      FIG. 1  is an illustration of a brake monitoring system, according to an embodiment of the present invention; 
           [0019]      FIGS. 2A-2D  are illustrations of a chassis communications module of the brake monitoring system of  FIG. 1 ; 
           [0020]      FIG. 3  is a flow diagram of the blink code operation of the chassis communications module of  FIGS. 2A-2D ; 
           [0021]      FIG. 4  is a diagrammatic illustration of a harness connection between the chassis communications module of  FIGS. 2A-2D  and a laptop computer; 
           [0022]      FIGS. 5-7  are screenshots of a diagnostics program running on the laptop of  FIG. 4 ; 
           [0023]      FIG. 8  is a diagrammatic illustration of a handheld tool for use with the chassis communications module of  FIGS. 2A-2D ; and 
           [0024]      FIG. 9-16  are screenshots of the operation of the handheld tool of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0025]    Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a brake monitoring system  10  for use with a motor vehicle (not shown) is shown. The motor vehicle includes a plurality of brake actuators  12  (in the illustrated embodiment, the motor vehicle includes 4 brake actuators  12 ). In the illustrated embodiment, the brake actuators  12  are drum brakes. 
         [0026]    In general, the brake monitoring system  10  utilizes a plurality of sensors (see below) to continuously monitor the status of the brakes. One such system is disclosed in U.S. Pat. No. 6,411,206, which is hereby incorporated by reference. The brake monitoring system  10  includes an e-stroke sensor  14  mounted within each actuator  12  and a brake lining wear sensor  16 . The e-stroke sensor  14  sensing a parameter of the actuator  12  which may be used in detecting over-stroke fault conditions. In one embodiment, the estroke sensor  18  provides real-time brake pressure application readings. Real-time brake pressure applications readings are transmitted via the J1939 network and can also be stored locally on the chassis communications module and may be downloaded off the vehicle and stored, e.g., on a diagnostics tool (see below). The brake lining wear sensor  16  is located within the brake lining of each set of brakes on the motor vehicle, and is described more fully below. An additional sensor may detect pushrod extension. 
         [0027]    In an alternate embodiment, the brake actuators  12  are disc brakes. If disc brakes are utilized, the sensors  14  are used to measure brake application which then may be used to detect, inter alia, an over-stroke condition. In one aspect a position sensor may be used to sense the position of the lever arm or caliper of the disc brake actuator  12 . An over-stroke condition may be detected by a reed-type switch sensors. Other types of position and/or location sensors may be used to monitor brake application or extension or pressure. 
         [0028]    In one embodiment, the brake lining sensor  16  includes a wire embedded in a wearable material such as plastic, which is positioned within the brakes of the motor vehicle. As the material wears, the wire is exposed and a short-circuit condition is established. The short-circuit condition corresponds to a predetermined amount of brake lining wear, i.e., lining “low”. After continued wear, the wire is broken and an open circuit condition is established. In one embodiment, the open circuit condition corresponds to a lining depleted condition. 
         [0029]    The brake monitoring system  10  includes a chassis communications module  20 . The sensors  14 ,  16 ,  18  are electronically coupled to the chassis communications module  20  through a wire harness  22 . In one embodiment of the present invention, the chassis communications module  20  is located on the motor vehicle in a location accessible to a technician, and generally, not viewable in the cab of the motor vehicle. 
         [0030]    In an alternate embodiment, the chassis communications module  20  is located within the cab. This would allow many of the functions of the communications module  20  to be performed in the cab by the driver. 
         [0031]    The system  20 :
       detects broken sensor wire/malfunctioning sensor at each wheel of the motor vehicle;   detects non-functioning actuator;   detects brake pushrod extension fault using an algorithm based on brake pressure, pushrod extension and time;   provides overstroke fault detection;   logs, and may transmit off-board, real-time brake pressure readings;   provide fault detection based on brake pressure sensor readings; and   provide brake lining wear.       
 
         [0039]    Brake pressure readings may be used to determine if the brakes are being applied, e.g., during a test procedure. Brake pressure information may also be used or displayed on a handheld tool (see below) for viewing by a technician during diagnostics. For example, the actual brake pressure may be used by the technician to determine if there is a brake overstroke problem. In a specific example, brake overstrokes are checked with 80-90 PSI applied to the brake system. If an overstroke occurs at 80-90 PSI or below it is valid. If it occurs over 90 PSI it is not valid. Typical vehicle brake systems can supply air pressure up to about 120 PSI maximum. 
         [0040]    In one embodiment, the chassis communications module  20  provides an interface to a handheld diagnostics tool (see below) and/or an interface to a computer or laptop running a diagnostics program (see below). In the illustrated embodiment, the interfaces are providing through connectors which provide an SAE J1708 interface, a RS-232 interface, and an SAE J1939 interface, respectively, for the diagnostic tool and/or the computer/laptop. 
         [0041]    The system  10  has a plurality of warning lights to convey specific information to an operator or a technician (see below). 
         [0042]    With specific reference to FIGS.  1  and  2 A- 2 D, the chassis communications module  20  includes a push button  22  which initiates a blink code sequence which is displayed through all system warning lights simultaneously. 
         [0043]    In the illustrated embodiment, the system  10  has up to 4 warning lights available: 
         [0044]    Warning Light 1: Tractor/Truck/Bus Brake Monitor Warning 
         [0045]    Warning Light 2: Tractor/Truck/Bus Lining Warning 
         [0046]    Warning Light 3: Trailer Brake Monitor Warning 
         [0047]    Warning Light 4: Trailer Lining Warning 
         [0048]    The system  10  is designed to continuously monitor the motor vehicle&#39;s braking system while in operation. When a fault is occurring it is considered to be active and will turn ON the appropriate warning light. For example, if a tractor has an active dragging brake the Tractor/Truck/Bus Brake Monitor Warning Light will turn ON but the other lights will remain off. When the fault is no longer active or has been repaired the warning light will turn OFF. 
         [0049]    The system  10  is capable of displaying both active and in-active (stored) fault information using a series of simple blink codes and the system warning lights. 
         [0050]    In the illustrated embodiment, the chassis communications module includes a push button  24 . Actuation of the push button  24 , initiates the blink code sequence which is displayed through all of the system warning light(s) at once. All of the warning lights blink the same fault code simultaneously. Table 1 presents an exemplary blink code sequence. 
         [0051]    In the exemplary blink code sequence, a first digit of “1” followed by a second digit of “1” means that there is not fault. 
         [0052]    A first digit of a “3” through “6” means that there is some type of brake related fault. The second digit identifies the brake actuator  12  with the related fault. In the illustrated embodiment, the brake actuator is identified by axle and left or right side. 
         [0053]    A first digit of “7” means that there is a system fault which is identified by the second digit. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Exemplary Blink Code Sequence. 
               
             
          
           
               
                 First 
                 Second 
                   
                   
               
               
                 Digit 
                 Digit 
               
               
                   
               
               
                 1 
                 1 
                 No fault 
                   
               
               
                 2 
                 1 
                 Non-functional brake 
                 (Axle 1 - left) 
               
               
                 3 
                 2 
                 Over-stroke 
                 (Axle 1 - right) 
               
               
                 4 
                 3 
                 Dragging Brake 
                 (Axle 2 - left) 
               
               
                 5 
                 4 
                 E-stroke sensor fault 
                 (Axle 2 - right) 
               
               
                 6 
                 5 
                 Lining wear wearing 
                 (Axle 3 - left) 
               
               
                   
                 6 
                 Lining wear wearing 
                 (Axle 3 - right) 
               
               
                   
                 7 
                 Lining wear wearing 
                 (Axle 4 - left) 
               
               
                   
                 8 
                 Lining wear wearing 
                 (Axle 4 - right) 
               
               
                 7 
                 1 
                 E-stroke system fault 
                 Pressure transducer 
               
               
                   
                 2 
                 Lining wear wearing 
                 SAE J1708/J1939 Comm. 
               
               
                 10 
                   
                 Fault codes cleared 
               
               
                   
               
             
          
         
       
     
         [0054]    With particular reference to  FIG. 3 , an exemplary blink code fault retrieving process is illustrated. The system  10  will display blink codes for only active faults only when an active fault is occurring. The warning lamp will be ON when the system  10  is operating and an active fault is occurring. The active fault will need to be repaired and the warning light will need to be OFF before in-active stored faults can be retrieved with this blink code method. If the blink code sequence is initiated when the warning light is OFF then stored fault codes will be displayed. 
         [0055]    The Blink Code Display Sequence is as follows:
       1. To retrieve the active or in-active stored fault codes, press the push button  24  on the front of the chassis communications module  20  for 1 second and release. This will start the blink code sequence.   2. Watch the warning light(s) and count the blink codes.   3. The Blink Codes will be displayed in a loop until the ignition power is shut off or the fault codes are cleared.   4. To clear the fault codes press and hold the push button  24  on the front of the chassis communications module  20  for a minimum of 5 seconds and release. The warning light will blink 10 times acknowledging that the stored fault codes have been cleared.       
 
         [0060]    The Blink Code Sequence will use the following timing: 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Blink Code Timing: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0.5 seconds 
                 Lamp On 
               
               
                 0.1 seconds 
                 Lamp Off 
               
               
                 1.5 seconds 
                 Pause In-Between Digits 
               
               
                   4 seconds 
                 Pause In-Between Faults 
               
               
                   
               
               
                 Notes: 
               
               
                 1. It is a good idea to have a pencil and paper ready to write down the blink codes as they are displayed. 
               
               
                 2. Pressing the CCM push button for 5 seconds will only clear stored fault codes and will not repair an issue with the foundation braking system which is causing the fault. 
               
               
                 3. With an active e-stroke fault (warning light ON) the e-Stroke system will broadcast the applicable SAE J1708 and/or J1939 code. 
               
             
          
         
       
     
         [0061]    Example Blink Code Definition:
       Brake System Fault: Axle  2  Right—Dragging Brake   Blink Code: 4-4   P Brake System Fault: SAE J708/J1939 Communications   Blink Code: 7-2   Brake System Fault: None   Blink Code: 1-1       
 
         [0068]    While the above described a blink code sequence utilizing 4 lights, it should be noted that other designs are possible within the scope of the present invention. For example, the communications module  20  could utilize a display capable of displaying text messages communicating the fault messages. 
         [0069]    As discussed above, the controller  10  provides an interface for connection to a diagnostic tool  30  which may be embodied in a hand held tool, a computer or laptop  30  for downloading of stored sensor data and the performance of diagnostics and testing. In one embodiment, the diagnostic tool  30  may be used to run a diagnostic program to acquire the following information from the chassis communications module  20 . 
         [0070]    Current Wheel Specific Brake &amp; Lining Status 
         [0071]    Stored Fault History 
         [0072]    System Status 
         [0073]    CCM Information: Software Version, Configuration, Serial Number. 
         [0074]    In one embodiment, the diagnostics tool  30  is provided at a location where service may be performed and is generally not permanently located on the vehicle. In an alternate embodiment, the diagnostics tool  30  is an on-board tool which may be either connected to the system  10  in the cab or may be permanently mounted within the cab and may be connected to the communications module  20 . 
         [0075]    In one embodiment, a RS-232 Diagnostic Program Kit may be provided. The kit may include: a Diagnostic Program Software CD, a 10 ft RS-232 Diagnostic/Programming Harness, and a USB High Speed Serial Adapter Harness. 
         [0076]    Set-Up Instructions: 
         [0077]    1. The supplied Diagnostic Harness P/N 8290220 connects the diagnostic tool  30  to the chassis communications module  20 . Plug the White 4-Pin connector into to the chassis communications module  20  P2 connector as shown in  FIG. 4 . 
         [0078]    2. Connect the DB9 connector into the tool&#39;s serial COM port. If a serial COM port is not available on the computer then the USB High Speed Serial Adapter Harness must be used. Simply plug the DB9 connectors together, and then plug the adapter harness USB connector into a USB receptacle on the computer. 
         [0079]    3. The RS-232 Diagnostic Program can be run directly from the supplied CD. Place the RS-232 Diagnostic Program CD into the appropriate drive on the computer. Access the contents of the CD through the CD Drive Window. Start the RS-232 Diagnostic program by double (left) clicking on the e-STROKE RS-232 DIAGNOSTIC.exe file as shown below in  FIG. 5 . 
         [0080]    4. Once the RS-232 Program window is open the appropriate COM port must be selected. See  FIG. 6 . Typically the DB9 connector will operate as COM  1  where equipped. The USB High Speed Serial Adapter will be assigned a COM port number when connected. The COM port assigned to the USB Adapter Harness can be looked up in the Device Manager. See Step 5. 
         [0081]    5. To locate the Computers Device Manager Follow these Steps. Note: This instruction applies to Windows applications. 
         [0082]    Select the Start Button, Settings, and then Control Panel. 
         [0083]    Once the Control Panel Window is open select the System Icon. 
         [0084]    Once the System Properties Window is open select the Hardware Tab and then the Device Manager Button. 
         [0085]    With the Device Manager open, locate the Ports (COM &amp; LPT) item. 
         [0086]    Left Click the Cross next to “Ports (COM &amp; LPT)”. 
         [0087]    All of the active COM ports will now be displayed with number assignments. 
         [0088]    Find the COM port which lists the USB Adapter and note the COM number. 
         [0089]    6. After selecting the appropriate COM port number you must then select the main display field. Click your mouse anywhere in the display window. This will allow you to continue interfacing with the Diagnostic program rather than the COM port setting. 
         [0090]    7. The e-Stroke RS-232 Diagnostic Program is now ready to acquire data from the system  10 . 
         [0091]    Diagnostic Program Operating Instructions: 
         [0092]    The RS-232 Diagnostic Program has 2 different display windows which provide the following e-Stroke Brake &amp; System information (See  FIGS. 6 and 7 ): 
         [0093]    CCM Data Window Information: 
         [0094]    CCM Serial Number 
         [0095]    Software Version Number 
         [0096]    Axles with Brake Stroke Sensors 
         [0097]    Axles with Lining Wear Sensors (Drum/Disc) 
         [0098]    CCM Type 
         [0099]    J1708 Status 
         [0100]    J1939 Status 
         [0101]    Brake Data Window: 
         [0102]    Wheel specific data is displayed and refreshed using the B command. (See  FIG. 5  Below) 
         [0103]    Brake Actuator Stroke Status—Displays Current Active Status with B command. 
         [0104]    Brake Stroke Fault Occurrence Counts—Displays Non-Current Stored Fault Counts. 
         [0105]    Brake Lining Status—Displays Current Active Status with B command. 
         [0106]    Brake Application Pressure—Displays Current Application Pressure with B command. 
         [0107]    Pressure Transducer Fault Occurrence Count—Displays Non-Current Stored Fault Count 
         [0108]    CCM Serial Number 
         [0109]    Software Version Number 
         [0110]    Axles with Brake Stroke Sensors 
         [0111]    Axles with Lining Wear Sensors (Drum/Disc) 
         [0112]    CCM Type 
         [0113]    The RS-232 Diagnostic Program can be operated using the following keys: 
         [0000]    B—Pressing B will acquire brake data that is current/active in the CCM when the button is pressed.
 
C—Pressing C will clear the stored fault codes from the CCM.
 
M—Pressing M will display the CCM information.
 
         [0114]    8. Press one of the Function Keys and the RS-232 Diagnostic Program will automatically acquire the desired data from the chassis communications module. Pressing B additional times will acquire updated brake data. Note that each time B is Pressed the brake data is refreshed and replaces the previously displayed data. The displayed data must be saved if a record is required. Use the slider on the right of the window to navigate the report. 
         [0115]    9. The displayed brake data or CCM information can be saved by Pressing the Save button. A Save Window will open prompting for a file name and save location. Enter the information as desired and press Save. The RS-232 Diagnostic Program will then save a Text (.txt) file. See  FIG. 7 . 
         [0116]    If a .txt format is not desired then the displayed data can be copied and pasted into the desired program. 
         [0117]    10. The displayed brake data can also be printed by Pressing the Print button. This program will print to the default printer which is set on the computer that is being used. 
         [0118]    Saved and Printed Brake Data will include a Date and Time Stamp at the beginning of the report. 
         [0119]    With particular reference to  FIGS. 8-16 , the system  10  may also include a handheld diagnostic tool  30 . The brake monitoring system  10  continuously monitors the brake status of the motor vehicle. As brake faults occur, the system  10  sends SAE J1708/J1939 fault codes over the vehicle&#39;s J1708 or Controller Area Network (CAN) where applicable. 
         [0120]    The handheld tool  30  monitors the vehicles J1708 or J1939 CAN network for the system status and brake fault codes. All system brake faults are published SAE J1708/J1939 codes (See Engineering Bulletin EB 08-025 e-Stroke SAE Fault Codes rev. 01.xls) 
         [0121]    The handheld tool  10  can be easily used with the supplied diagnostic harness which can connect to either a 6 or 9-pin diagnostic port (OBD) connector. When connected to the vehicle&#39;s diagnostic port connector the handheld tool  30  will automatically turn on and establish communication with the chassis communications module  20 . 
         [0122]    The handheld tool  30  displays real time system status, lining wear (if applicable) and active brake faults. In addition the brake fault history can be acquired from the system. Vehicle speed and brake application pressure are also available for diagnostic purposes. 
         [0123]    In one embodiment, the handheld tool  30  may be supplied in a toolkit. The toolkit may consist of the following components: the handheld tool  30  and a display diagnostic harness. The diagnostic harness is capable of connecting the handheld tool  30  to the vehicle&#39;s OBD port. Standard 6 and 9 pin connector plug leads are included on the harness to connect the display to the vehicles OBD circuit. Vehicles with 6 Pin OBD port connectors typically only include SAE J1708. Vehicles with 9 Pin OBD port connectors typically include both SAE J1708 and J1939. 
         [0124]    To utilize the handheld tool  30 , connect the diagnostic harness  12  pin connector labeled “Display” into the receptacle on the back of the tool  30 . Next connect either the 6 or 9-pin diagnostic connector into the available OBD port on the vehicle. The tool  30  will receive vehicle power and automatically turn ON and search for the system  10  on either the SAE J1939 or J1708 circuit. The tool&#39;s display will indicate which communications protocol (J1708 or J1939) is being used. The tool  30  is now connected and ready for use. 
         [0125]    Additional Display Connection Option: 
         [0126]    In the illustrated embodiment, the system&#39;s  10  fault history and brake application pressure is only available on the J1939 circuit. J1708 is only capable of displaying the system faults in real time as they occur. If a system  10  is installed on a vehicle and connected to the J1708 circuit, a direct J1939 connection can be made to the chassis communications module  20  to acquire fault history and brake application pressure. 
         [0127]    To access vehicle power, connect either the 6 or 9 pin diagnostic connector into the available OBD port on the vehicle. Next connect the 4-Pin connector labeled “P3” into the P3 connector on the chassis communications module  20 . The tool&#39;s display will now have power and a direct connection to the J1939 connection on the chassis communications module  20 . 
         [0128]    When the tool  30  is plugged in it will show a splash screen while the tool  30  conducts a self test. When the self test is complete a home screen will be displayed. The home screen displays system status as well as the active diagnostic circuit being used (see  FIG. 8 ). 
         [0129]    The tool  30  can be navigated using the 5 soft keys (labeled “1”, “2”, “3”, “4”, and “5”) on the front of the display. A Button Bar graphic (see, for example,  FIG. 9 ) will appear after a soft key is pressed indicating the menu options available. With the button bar displayed the appropriate soft key below the icon can then be pressed selecting the option that is desired. The Button actions will vary depending on the options displayed on the Button Bar (see  FIGS. 8 ,  9 , and  13 ). 
         [0130]    The tool  30  requires connection to either the vehicle&#39;s SAE J1708 or J1939 circuit to retrieve data from the system  10 . If communication over one of these circuits is not present then the icon shown in  FIG. 10  will appear. When communication is restored the icon will disappear and the active CAN circuit will be displayed on the home screen ( FIG. 11 ). 
         [0131]    With reference to  FIG. 1 , a vehicle speed and brake application pressure diagnostic page displays real time vehicle speed and brake application pressure. This data can be used to aid in the diagnosis of a reported brake fault. 
         [0132]    With reference to  FIG. 12 , a system fault is considered active while the fault is occurring. Active faults are displayed using flashing pop up alarm windows on the tool&#39;s display. The alarm window appears overlaid on the current screen in use, showing details of the fault which is occurring. 
         [0133]    Pressing any key will acknowledge the fault and display the active alarm (fault) page. This page shows the list of active faults occurring with the system  10 . The button bar icons  34  show the navigation and function options available on the page (See  FIG. 13 ). 
         [0134]    Key Functions: 
         [0135]    The Arrow keys 1 &amp; 2 can be used to scroll through the active faults. An Active Alarm can be acknowledged by pressing key 3. The Inactive Stored Fault Table can be accessed by pressing key 4 for 5 seconds. 
         [0136]    The active alarms must be acknowledged by pressing key 3 before this page can be exited (see  FIG. 14 ). 
         [0137]    Key Functions: 
         [0138]    The Inactive Stored Fault Table can be exited by pressing key 5. 
         [0139]    If the Active Fault Table Page is exited while there is still an active alarm present a caution icon will appear indicating that an active alarm is still present. The active fault must be repaired before the caution icon will go away (See  FIG. 15 ). 
         [0140]    Faults which occur during operation of the system  10  will be stored in the chassis communications module&#39;s memory, up to 126 counts per fault per wheel. The fault count will increment once per fault occurrence regardless of the duration of the active fault. 
         [0141]    The stored fault alarms can be accessed from the chassis communications module&#39;s memory by accessing the Active &amp; Inactive Fault Table. The fault table can be accessed from the home page by pressing the Active &amp; Inactive Fault Table key. The Active fault table will then be displayed. The Active &amp; Inactive Fault Table key must then be pressed again for 5 seconds to display the stored faults from the chassis communications module&#39;s memory (see  FIG. 9 ). 
         [0142]    Inactive faults are marked with an inactive icon (See  FIG. 16 ). 
         [0143]    Key Functions: 
         [0144]    The Arrow keys 1 &amp; 2 can be used to scroll through the inactive faults. 
         [0145]    Press the “HOLD RESET” Key 3 for 5 seconds to clear the chassis communications module fault history. 
         [0146]    The Inactive Stored Fault Table exited by pressing the return key 5. This will return to the Inactive fault table where the key 5 can then be pressed to exit to the home screen. Note: Stored Inactive faults can only be accessed from the chassis communications module through the J1939 circuit. J1708 does not support the chassis communications module fault history retrieval or brake application pressure. 
         [0147]    The contrast and back light of the tool&#39;s display screen can be adjusted. Access the contrast adjustment screen by pressing the Contrast &amp; Back Light Adjustment key from the home page. Follow the button bar icons to adjust as required. 
         [0148]    The display configuration menus can be accessed from the home page. With the Button Bar  34  not visible on the screen, press key 5 for 5 seconds to display the Configuration Menu. Select Settings or System to continue. 
         [0149]    Key Functions: 
         [0150]    The Arrow keys 1 &amp; 2 can be used to scroll through the configuration options. 
         [0151]    Arrow key 4 will select the option indicated by the arrow. 
         [0152]    Key 5 will exit the Configuration Menu Page returning to the home page. 
         [0153]    The following display settings can be adjusted to meet the application requirements: 
         [0154]    Display Settings Menu: 
         [0155]    Units—Units can be adjusted between English and Metric. 
         [0156]    Language—The Language displayed can be changed. 
         [0157]    Bleep—The audible key bleep can be turned on or off. 
         [0158]    Backlight—Backlight mode and level can be adjusted. 
         [0159]    System Menu: 
         [0160]    Demo—Three Demo options are available to illustrate the features of the display. Select 0 to shut the Demo option OFF. 
         [0161]    Restore Defaults—This will reset the display back to factory settings. 
         [0162]    COM—Viewer Displays real time data traffic on the J1708 &amp; J1939 circuits. 
         [0163]    Data link Settings—Allows Adjustment of J1939 &amp; J1587 Data Link Settings. 
         [0164]    About—Displays Display unit information. 
         [0165]    Key Functions: 
         [0166]    The Arrow keys 1 &amp; 2 can be used to scroll through the display options. 
         [0167]    Arrow key 4 will select the option indicated by the arrow. 
         [0168]    Key 5 will return to the previous page. 
         [0169]    Diagnostics and Limp-Home Features 
         [0170]    The system can record and store all brake pressure readings and fault conditions. These may be downloaded to an off-site or off-vehicle device for storage and diagnostic purposes. The data stored in the system  10  may be transmitted in real-time through a wireless connection or transmitted in batch mode. The data may also be stored redundantly in a black-box type of device. 
         [0171]    The data, e.g., application of the brake measure via brake extension or brake pressure, may be used during accident investigations. 
         [0172]    Additionally, the data may be used in real-time to prevent unsafe operation of the vehicle. For example, if the brake system experiences a fault, generally the vehicle may still be operated. However, if the brake condition renders the vehicle unsafe to operate, the system  10  may be the ability to safely affect or limit the vehicle&#39;s operation. For example, if one of the brakes is experiencing a dragging brake condition the system  10 , a potential fire condition may exist on the respective tire. If this occurs, the system  10  may send a signal to an engine control module to throttle back the vehicle, or limit the speed of the vehicle and/or the RPM of the engine. 
         [0173]    Obviously, many modifications and variations of the present invention are possible in light of the above teachings.