Edmunds Answers



  • MrShift@Edmunds 03/18/10 5:38 pm PST

    Sounds like a PASSLOCK system problem. You might be having trouble in any number of places, but the cylinder lock HOUSING could be one of them, as it contains coded information. Your key does not, it performs a purely mechanical function.

    Here's a brief rundown:

    The Passlock(TM) system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate. The Passlock(TM) controller reads the coded Passlock(TM) data signal. The data consists of a voltage generated by a voltage divider network created between the Passlock(TM) assembly and the Passlock(TM) controller. If the data is correct , indicating rotation of the lock cylinder with the proper mechanically cut key, then the Passlock(TM) controller sends a password to the powertrain controller via serial data to indicate that fuel should be delivered to the engine. The Passlock(TM) controller also interfaces with the driver displays subsystem to indicate, via a security telltale, the Passlock(TM) subsystem status and acute subsystem failures.

    The components of the Passlock(TM) system are as follows:

    • The ignition switch

    • The body control module (BCM)

    • The security indicator on the instrument cluster

    • The engine control module (ECM)

    The body control module (BCM) contains the logic of the theft deterrent system. The BCM provides the 5-volt reference to operate the Passlock(TM) sensor. The BCM also measures the voltage of the off/run/crank voltage. The voltage measured will indicate whether the Passlock(TM) sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage to a previously learned voltage code. If the voltage codes match, the BCM sends a serial data message containing a password to the engine control module (ECM). If the voltage codes do not match, or the voltage is in the tamper range, or there is a circuit fault, the BCM will not send the correct password to the ECM, and the vehicle will not start.

    The engine control module (ECM) contains the remainder of the logic of the theft deterrent system. If a serial data message containing a valid password is received from the body control module (BCM), the ECM will continue to allow the fuel injectors to operate. The ECM will allow the fuel injectors to operate until it decides there is no valid password coming from the BCM. If the ECM does not receive a serial data message, or receives a serial data message with an incorrect password, the engine will crank and will not run or will start and stall immediately.

    When it receives a password which is incorrect or a password which indicates tamper and the engine control module (ECM) disables the fuel injectors, the fuel injectors remain disabled for 10 minutes even if the ignition switch is turned from the RUN position to the OFF position.

    The following components contain codes or passwords, or must learn codes or passwords for the Passlock(TM) system to allow the vehicle to start:

    • The ignition switch

    • The body control module (BCM)

    If any of these parts are replaced, a learn procedure must be performed. Refer to Programming Theft Deterrent System Components. If parts are replaced and a learn procedure is not performed, the engine will crank and will not run or will start and stall immediately.

    As I said, the key itself doesn't "learn" or "know" anything but there are other components in the PASSLOCK system that do contain "logic", and if the ECM can't get a good reading from the key cylinder *housing* (not the key or the key cylinder), or the BCM, then we'll have this problem.

    I can't say what it might cost to diagnose and correct the problem. A good locksmith might be able to handle this.


  • Stever@Edmunds 03/18/10 8:31 pm PST

    You can reply in this thread by clicking the Answer this Question button and that will help keep all the information in one spot. Thanks!


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