Patent Publication Number: US-6700220-B2

Title: Remote control pass-key module for anti-theft system equipped vehicles and installation method

Description:
FIELD OF THE INVENTION 
     The present invention relates to vehicle remote starting systems, and more particularly, to electronic circuitry for bypassing the electronic anti-theft system of a vehicle to permit starting of the engine from a remote location. The electronic module of the present invention will be referred to as an electronic pass-key module (PK module) throughout the description. 
     BACKGROUND OF THE INVENTION 
     Vehicle manufacturers are installing anti-theft systems on many vehicles. Some of them are now relying on the wireless transmission of a coded signal from a transponder embedded into the grip of the mechanical ignition key, thus providing an electronic key, in order to enable starting of the engine and driving of the vehicle. Typically, to drive the vehicle the electronic key is inserted into the ignition cylinder and the electronic ID code is read by a short range transceiver usually located near the ignition cylinder. The transceiver then communicates the ID code to a vehicle electronic control unit (VCU) for validation and enabling of engine starting. Such a feature obviously helps deterring theft since the driver must be in possession of an ignition key with a compatible mechanical code plus a valid electronic ID code to be communicated to the vehicle control unit to activate the vehicle functions and drive away with the vehicle. Usually, these systems are first initialised by teaching the vehicle control unit the transponder ID code of an associated ignition key and thereafter require that same ID code to be communicated to the control unit to enable vehicle operation. Examples of such anti-theft systems are described in U.S. Pat. No. 5,555,863 delivered to Kokubu in 1996 and U.S. Pat. No. 5,818,330 granted to Schweiger in 1999. 
     Some variations to the above concept are known but all consist in communicating an electronic ID signal to a control unit in order to enable engine starting. For instance, in U.S. Pat. No. 5,184,584 (Cantrell—1993) and U.S. Pat. No. 5,612,578 (Drew—1997), an electrically resistive pellet is embedded into the ignition key and the ID signal is determined by the resistance value. 
     It shall be pointed out that in most of these systems, the vehicle engine can be started if one knows the ignition key electronic ID code and can communicate it to the vehicle control unit, while providing an electronic circuitry to control the vehicle function as in any common remote starting system. To drive the vehicle, however, the key must still be introduced into the ignition cylinder to activate the ignition switch and let the vehicle control unit (VCU) take over full vehicle control. 
     Resistive coded anti-theft systems can be bypassed relatively easily to enable remote engine starting as described U.S. Pat. Nos. 5,184,584 and 5,612,578. One merely has to measure and mimic the appropriate resistor value with a fixed or variable resistor connected to the input connector to bypass the anti-theft system and enable engine starting. Transponder based systems are much more difficult to bypass since it is practically impossible to read the key ID code. Therefore, only the vehicle or anti-theft system manufacturer can provide a system in which a given start enabling coded signal can be transmitted by either the ignition key transponder or a remote transmitting unit to enable starting of the engine from a distance without trigging the anti-theft system, as provided for instance in U.S. Pat. No. 5,818,330. In order to provide a still higher level of reliability, at least one vehicle manufacturer (Nissan) is using a dual electronic code protocol in addition to the usual mechanical coding of the ignition key. The vehicle control unit communicates a random password to be memorised by the ignition key transponder every time the ignition is cut-off. To start the engine the next time, the key must be inserted properly into the ignition cylinder, then the key ID code is verified and the transponder is finally asked by the VCU to communicate the last password received. Since that password is random and is only known by the VCU and the key transponder, a very high level of safety is thereby achieved. 
     The aforementioned systems are performing so efficiently that they cause a major problem to remote starter manufacturers and installers trying to retrofit a remote starting system on vehicles equipped with such transponder based anti-theft systems. Indeed, they must find a way to bypass the verification routine of the VCU and/or the transceiver, or mimic the coded signal and the possible password normally transmitted by the ignition key transponder to start the engine successfully. That shall be accomplished while preserving the normal operation and performance of the theft-deterrent system of the vehicle. 
     Most available solutions to the above problem merely reside in providing the vehicle control unit with a mimic of the signal normally communicated by the ignition key transponder. A basic way to do that is to use a valid electronic ignition key (mechanical code plus transponder) dissimulated in the vehicle and inductively coupled to the transceiver unit of the key cylinder assembly through induction coils and a relay contact. Therefor, when the remote starting system is activated through the remote transmitter, the relay is energised and the spare key becomes inductively coupled to the transceiver that can read the ID code transmitted from the key transponder and communicate it or a confirmation signal upon request from the VCU to enable engine starting. That technique suffers from three main drawbacks: 1) an expensive transponder coded key must be purchased from the vehicle manufacturer and validated by the vehicle control unit, 2) it is relatively easy for a thief, to find the hidden key and merely disconnect it and use it normally in the ignition cylinder to drive away with the vehicle, which practically eliminates the usefulness of the anti-theft system, if not worse, and 3) the installation is critical for proper operation; the key must be installed as near as possible to the key cylinder transceiver, the coils must be wound carefully and precisely and nevertheless the risks of malfunction remain high. 
     There is thus a need for an electronic pass-key module (PK module) which can be used to retrofit a remote starting system on a transponder based anti-theft system equipped vehicle, without adversely affecting the normal operation and reliability of said anti-theft system. 
     SUMMARY OF THE INVENTION 
     More specifically, in accordance wits the invention, there is provided a pass-key electronic module for enabling remote control of a function of a motor vehicle equipped with a key identity code verifying anti-theft system under control of a vehicle control unit connected to a key identity code receiving sensor through a data communication link and an enable line, comprising: 
     (a) a communication circuit enabling communications with the vehicle control unit through the data communication link; 
     (b) an input receiver circuit for receiving a command signal from a remote control system controller; 
     (c) a switching circuit for disabling the sensor from communicating with the vehicle control unit upon sensing of the command signal through the input circuit; and 
     (d) a memory circuit storing an operating program and an identity code subject to validation by the vehicle control unit. 
     The present invention also relates to a method for enabling remote control of a function in a motor vehicle equipped with a key identity code verifying anti-theft system under control of a vehicle control unit connected to a key identity code receiving sensor through a data communication link and an enable line, said method comprising: 
     (a) providing a pass-key electronic module with communication and switching capability, in which an identity code is memorized; 
     (b) connecting said pass-key module for communication with the vehicle control unit through the communication data link; 
     (c) connecting the pass-key module in series with the sensor enable line for controlled switching of the line; 
     (d) communicating the identity code to the vehicle control unit for validation of the identity code; and 
     (e) connecting the module to a remote control system controler output so that when a command signal is generated by the controller, the module switches the key identity code sensor enable line open, thus disabling the sensor, and communicates the validated identity code to the vehicle control unit which then enables a function in the vehicle. 
    
    
     The foregoing and other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the appended drawings: 
     FIG. 1 is a block circuit diagram showing the interconnection between a first illustrative embodiment of the pass-key module of the present invention, the remote starting system controller and the transponder based anti-theft system of a motor vehicle; 
     FIG. 2 is a flow diagram showing the algorithm of operation of the first illustrative embodiment of the remote starter pass-key module of the present invention illustrated in FIG. 1; 
     FIG. 3 is a detailed circuit schematic of the first illustrative embodiment of the remote starter pass-key module of the present invention pursuant to FIGS. 1 and 2; 
     FIG. 4 is a block circuit diagram showing the interconnection between a second illustrative embodiment of the pass-key module of the present invention, the remote starting system controller and the transponder based anti-theft system of a motor vehicle using a variable password as part of the identity verification protocol; 
     FIGS. 5 a  and  5   b  are a flow diagram showing the logical algorithm of operation of the second illustrative embodiment of the remote starter pass-key module of the present invention, illustrated in FIG. 4; 
     FIG. 6 is a detailed circuit schematic of the second illustrative embodiment or the remote starter pass-key module of the present invention, pursuant to FIGS. 4 and 5; 
     FIG. 7 is a block circuit diagram showing the interconnection between a third illustrative embodiment of the pass-key module of the present invention, the remote starting system controller and the transponder based anti-theft system of a motor vehicle; 
     FIG. 8 is a flow diagram showing the logical algorithm of operation of the third illustrative embodiment of the remote starter pass-key module of the present invention, illustrated in FIG. 7; and 
     FIG. 9 is a detailed circuit schematic of the third illustrative embodiment of the remote starter pass-key module of the present invention, pursuant to FIGS. 7 and 8. 
     Similar reference numerals refer to similar parts throughout the various Figures. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Illustrative embodiments of the remote starter module for anti-theft system equipped vehicles according to the present invention will now be described in detail referring to the appended drawings. 
     Referring to FIG. 1, there is illustrated a typical system installation for a Ford vehicle, comprising the electronic pass-key module  10  cooperating with a conventional remote starting system and a transponder based anti-theft system (SECURILOCK). The conventional remote starting system comprises a remote transmitter  20  provided with an antenna  21 , and a controller  22  installed in the vehicle and comprising an antenna  23  and a plurality of inputs and outputs including at least a 12V supply  24 , a GWR (ground when running) output  25 , an ignition output  26 , a brake-on input  29 , a starter output  27  and an accessory output  28 . The SECURILOCK anti-theft system comprises an electronic key  30  provided with a transponder  31 , a transceiver unit  32  incorporated into the key cylinder assembly  33 , and a vehicle control unit (VCU)  40  in communication with transceiver unit  32 . The key cylinder assembly  33  also includes at least an ignition switch  34  connected to an ignition wire  35 , a drive switch  36  connected to a drive wire  37 , and a 12V supply wire  38 . 
     The Ford SECURILOCK anti-thief system basically functions as follows. When a vehicle user introduces the electronic key  30  into key cylinder assembly  33  and selects the ignition position, the steering lock is released and the ignition switch  34  is closed connecting the 12V supply  38  to ignition wire  35  connected to the ignition input  39  of VCU  40 . Upon reception of an ignition signal, VCU unit  40  returns a 12V ignition supply through wire  41  (connected to wire  44  when the PK module  10  is not present or activated) to activate transceiver unit  32 . VCU  40  then enters into communication with transceiver unit  32  through data wires  42  and  43 . The transceiver unit  32  is then put into wireless communication with key transponder  31  requesting transmission of a key code signal then communicated to the VCU  40  through data-out wire  43 . VCU  40  compares the key code signal with the valid key codes stored into its memory and sends the appropriate outputs to start the engine if the received code matches one of the memory stored valid codes. Therefore, to start the engine, a user must be in possession of an electronic key  30  comprising a mechanical code permitting introduction into the key cylinder assembly  33  and a transponder  31  with an electronic code known by the VCU  40 . When the engine starts running, the key  30  is then set to the drive position of the key cylinder  33 , closing drive switch  36  and sending a 12V signal to VCU  40  through wire  37 , thus cutting-off the power to the starter while enabling the necessary functions to drive the vehicle. 
     That type of system features a programming function to enter new key codes for future use. The procedure requires two different valid keys to be inserted into the cylinder assembly  33  within a certain time delay. That puts the VCU  40  into programming mode so that the code of a third key inserted again within a certain delay is memorised by the VCU  40  and will then be considered a valid key code for starting the vehicle. It shall be noted that the SECURILOCK system requires a valid key code to start the engine, but once the engine is running, there is no further restriction than using a valid mechanical key to allow driving of the vehicle. 
     When a user wishes to start the vehicle from a distance, no key is inserted into the cylinder assembly  33 ; the validation procedure must then be fooled using the electronic pass-key module  10  of the present invention. As stated above, PK module  10  is designed to be used in co-operation with any existing remote starting system such as illustrated in FIG. 1, provided that the system&#39;s controller  22  is equipped with a GWR output  25 , which is a very common feature. Since it is not possible to know the codes of the valid existing electronic keys for a vehicle, there is no possibility to merely mimic one of those codes already stored in the memory of VCU  40  and requested by it to enable starting of the engine. However, the communication protocol between the VCU  40  and the transceiver unit  32  is known and common to most if not all of the SECURILOCK anti-theft systems installed. Therefore, PK module  10  is designed to communicate with VCU  40  with the same communication protocol as the transceiver unit  32 , and has its own ID code in the same format as a key transponder ID code. Accordingly, PK module  10  must be installed in a vehicle using a special method. 
     Firstly, the PK module  10  and the remote starting system controller  22  are hooked-up as indicated in FIG.  1 . Secondly, referring to the new key code programming procedure described above, two valid keys are required and must be inserted in the cylinder assembly  33  with the appropriate sequence to initiate the programming state of VCU  40 . Thirdly, within the allowed time delay, the GWR line  25  is activated (short to ground) which enables PK module  10  and disables transceiver unit  32  by disconnecting wire  44  from wire  41 . The VCU  40  then requests the PK module  10  to communicate the key ID code, at which time the PK module  10  communicates its own ID code thus being stored in memory and validated by the VCU  40  for future recognition. The GWR wire  25  can then be disconnected from the ground to resume normal operation of the anti-theft system. The initialisation procedure is now complete and the PK module  10  can be used to permit starting of the engine without an electronic key through activation of the GWR line  25  before the beginning of the verification procedure of VCU  40 . Therefore, the PK module  10  can co-operate with a common remote starting system as follows to allow a user to start the engine from a remote location. 
     The user depresses a switch button on remote transmitter  20  and a coded signal is transmitted from antenna  21  to base unit  22  of the conventional remote starting system through antenna  23 . It is also a common practice to incorporate such a transmitter and antenna into the grip of a mechanical key. After recognition and validation of the transmitter code, the base unit  22  sends a continuous low electrical signal at the GWR output  25  connected to the GWR input of PK module  10 , which immediately causes disconnection of wire  44  from wire  41  according to the electronic circuitry in module  10  (See FIG.  3 ). The base unit  22  then sends a 12V supply at its ignition output  26  connected to ignition wire  35  and ignition input  39  of VCU  40 . Then, VCU  40  senses the 12V ignition signal and returns a 12 V signal on wire  41 , trying to energise transceiver  32  to establish communication, but actually only trigging the PK module  10  which intercepts and blocks the signal. At that time the VCU  40  enters into communication with the PK module  10 , which responds with the appropriate communication protocol. The VCU  40  then requests a key ID code. The PK module  10  transmits its own ID code which is validated by the VCU  40  since it has been previously programmed into its memory as a new key code at the time of the installation of the PK module  10 , according to the aforementioned specific procedure. The VCU  40  being satisfied with the response then enables the engine starting functions, permitting effective engine starting under the control of the remote starter controller  22 , namely activating the vehicle starter through its starter output  27 . 
     According to the above procedure, the transceiver  32  has been totally disconnected and replaced with PK module  10  for the purpose of communicating a valid key code to the VCU  40 . Therefore, to drive away with the vehicle, a user merely has to use a key which is mechanically compatible with key cylinder assembly  33 , which includes of course the original electronic transponder key  30 . The key is inserted into the cylinder assembly  33  to select the drive position and close the drive switch  36 . When the brake pedal is depressed, the brake input  29  on the base unit  22  is activated, which in turn takes the GWR output  25  back to a Hi status and turns the controller  22  off, thus returning the full control to VCU  40  and transceiver unit  32  until the next remote starting command. 
     It is worth mentioning that the theft deterring performance of the anti-theft system is not significantly affected by the use of the PK module  10  since 1) one still needs a coded ID signal from a valid transmitter  20  provided by the remote starting system to start the vehicle. 2) Access to the GWR wire  25  can be mechanically restricted by using wires of the same colour taped together and no identification indicia on controller  22 . Indeed, it is a well known characteristic of all remote starting systems to enable starting of the engine by shorting the GWR wire  25  to ground. Therefore, the same usual precautions shall apply when such a system is used in co-operation with the PK module  10  of the present invention. 
     The operation of the PK module  10  described above will now be described in detail referring to FIGS. 2 and 3. 
     The structure of the PK module  10  is relatively simple as illustrated in FIG.  3 . The circuit basically comprises a power supply section  50 , a programmable integrated controller (PIC)  60  connected to a crystal providing the clock time basis to pins P 4  and P 5  of PIC  60 , and input and output interfacing components. The power supply section receives the 12V supply from the ignition output  41  of VCU  40  (see FIG. 1) and uses a 5V voltage regulator  51  with upstream and downstream capacitors to provide a 5V regulated voltage supply to PIC  60 . 
     The GWR output  25  from controller  22  normally supplies a 12V signal to the cathode of diode D 2  avoiding transmission of the signal to the 5V PIC circuit. When the GWR line  25  switches to a Lo logic status upon reception of an engine start signal by controller  22 , PNP transistor Q 1 , resistors R 5  and R 7  and pull down resistor R 6  provide a sharp Lo signal to input P 3  of PIC  60 , bypassing diode D 2  to avoid excessive potential difference between pin P 3  and the common (VSS pin). voltage drop. The data input  43  from an open collector transistor in VCU  40  is received in the PK module through a pull-up resistor R 3  connected to the 12V ignition input and reverse diode D 1  isolating the 12V signal from the 5V PIC circuit. Data is communicated by the VCU  40  by switching the open collector transistor to ground, thus providing Lo pulses to input pin,P 3  of PIC  60 . 
     Similarly, PIC  60  communicates with VCU  40  through output pin P 0 , base resistor R 4  and open collector transistor Q 3  sending a train of Lo pulses to the VCU data input  42 . Finally, output P 2  of PIC  60  provides the ignition out signal to wire  44  through zener diode D 3 , PNP transistor Q 2  and resistors R 1  and R 2 . Since the emitter of transistor Q 2  is connected to the 12V ignition input  41 , the 12V ignition signal from wire  41  is normally redirected to the transceiver unit  32  through wire  44  (FIG. 1) because pin P 2  of PIC  60  is set Lo so that the difference between the 12V ignition supply and the Zener voltage (typically set to approximately 9V) allows conduction in transistor Q 2 . However, when a Lo GWR input signal  25  indicates a remote starting condition, Pin P 2  of PIC  60  is set Hi to 5V which added to the zener voltage exceeds the 12V supply. Therefore, conduction in transistor Q 2  is not allowed, thus disconnecting wires  41  and  44  and disabling transceiver unit  32 . 
     Referring to FIGS. 2 and 3, the algorithm followed by PIC  60  is as follows: 
     The PK module  10  is dead until a 12V ignition signal appears at input  41 . When an ignition signal is sensed, the PIC verifies the status of GWR input  25 . If the input is Hi, ignition is being carried out using the key and the PK module simply redirects the ignition signal  41  to the transceiver unit  32  and waits until cut-off of the ignition. Otherwise, a Lo at GWR input  25  means a remote starting condition and PK nodule  10  does not activate ignition output  44  to transceiver unit  32 . The module then waits for a prompt from VCU  40  on data line  43  and confirms its presence through the appropriate handshaking protocol on data line  42 . The VCU then asks for the key ID code. The PIC responds by transmitting its own ID code, previously programmed into the memory of VCU  40  according to the special initialisation procedure described above. The ID code is thus compared and accepted by VCU  40  which enables engine starting. PK module  10  then waits for cut-off of the ignition for reset and will resume operation at the next ignition signal. 
     In an alternative, illustrative embodiment of the PK module  10  of the present invention, the module is carrying a changing password to be communicated to VCU  40  in addition to or in lieu of a fixed ID code. As an example, operation of the PK module with a Nissan anti-theft system illustrated in FIGS. 4 to  6  will be described hereinafter. 
     The Nissan anti-theft system can be schematically represented referring to FIG. 4, which is very similar to FIG. 1 as most changes involve the communication protocol and data transmissions. 
     In the Nissan anti-theft system, more autonomy is implemented into the transceiver unit  3 Z, such that all communications necessary to verify the ID code of the key transponder are handled by the transceiver itself. However, a further level of verification is taking place between the transceiver unit  32  and VCU  40 . Indeed, every time the VCU  40  is instructed to cut-off the ignition, it sends a password to the transceiver for storage into the memory of key transponder  31 . The following protocol is thus taking place when the key  30  is inserted into cylinder assembly  33  and set to the ignition position. The transceiver  32 , energised through ignition wires  41  and  44 , verifies the ID code of transponder  31  and finally asks for transmission of the stored password. It then initiates communication through proper protocol with VCU  40  on data line  42  to acknowledge ID code verification and transmit the password. VCU  40  then proceeds to password verification and enables engine starting if it matches the last transmitted password. 
     In such a case, it is not necessary for PK module  10  to possess an ID code. However, it shall be able to monitor the communications between VCU  40  and transceiver  32  and memorise the password when it is being transmitted on data line  42 . FIGS. 5 a ,  5   b  and  6  respectively illustrate the algorithm and the circuit schematic of the PK module for the Nissan anti-theft system. 
     When an engine start signal is transmitted by transmitter  20  to controller  22 , the resulting activation of GWR output  25  causes. PK module  10  to interrupt ignition supply to the transceiver  32  through wire  41 , The algorithm of the PIC  60  is thus so modified to initiate communication with VCU  40 , acknowledge ID code verification and communicate the last password gathered on communication line  42  and memorised. Upon reception of this information, VCU  40  enables engine starting. Although pass-key module  10  knows the password and engine is running, when the electronic key is inserted into the cylinder to drive the vehicle, pass-key module  10  asks the transceiver  31  for communication of the password in lieu of VCU  40  to comply with the transceiver protocol and avoid an error status. When pass-key module  10  is not activated through GWR line  25 , lines  41  and  44  are connected together through relay RLY  1 , for normal communication between transceiver  31  and VCU  40 . 
     A further illustrative embodiment of the pass-key module of the present invention for operation with a General Motors transponder based anti-theft system is illustrated in FIGS. 7 through 9. When remote starting system controller  22  is activated, providing a Lo output on GWR line  25 , ignition line  44  to transceiver  31  is disconnected through transistor Q 3  and timer U 1  is energised through transistor Q 2 . The power supply section is not required since timer U 1  can be operated directly from the 12V ignition supply. Upon application of a 12V supply at pin  8 , timer U 1  enters into an astable multivibrator mode and provides a train of pulses at output pin  3  at a frequency and duty cycle determined by the values of resistors R 3  and R 4  and capacitor C 3 . Output pulses are communicated to data output line  42  by NPN transistor Q 1 . Upon reception of such a pulse train conforming to a predetermined protocol, VCU  40  enables engine starting. Obviously, equivalent results would be obtained by using a programmable integrated computer instead of timer U 1 . 
     Therefore, It can be seen that the electronic pass-key module of the present invention can be advantageously used to interface practically any existing remote starting system to an anti-theft system equipped vehicle, without the limitations and drawbacks of the prior art solutions. A major characteristic of the PK module being that it bypasses the transceiver and does not require anybody to know a valid key ID code to install and operate the module. 
     The above described illustrative embodiments of the electronic pass-key module (PK module) for interfacing a remote starting system to anti-theft system equipped vehicles according to the present Invention present the advantage of overcoming limitations and drawbacks of the known solutions described in the background of the invention, and more specifically: 
     enable the retrofit installation of a conventional remote starting system on vehicles equipped with a transponder based anti-theft system; 
     are able to co-operate with a wide selection of conventional remote starting systems; 
     cannot be used by a thief to drive the vehicle and preserve the full usefulness of the anti-theft system; 
     can comply with variable password types of transponder based anti-theft systems; 
     do not require anybody to know the LO code of a valid key or card transponder or a password sent to a transponder by the vehicle control unit; and 
     are economical to produce with commonly available electronic components. 
     Although the present invention has been described by means of illustrative embodiments thereof, it is contemplated that various modifications may be made thereto without departing from the spirit and scope of the present invention. For example, different embodiments of the pass-key module can be made to adapt to the communication and programming protocols of different anti-theft systems than those described hereinabove. Also, although the pass-key module has been described as an interface for a remote starting system, it is contemplated that use of the module can by made without a remote starting system by trigging the GWR input manually or with another type of controller to enable starting of the engine without having to introduce a valid key into the key cylinder assembly. Accordingly, it is intended that the embodiments described be considered only as illustrative of the present invention and that the scope thereof should not be limited thereto but be determined by reference to the claims hereinafter provided and their equivalents.