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Thread: 98 silverado security light

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  1. #1
    Registered User haulinit's Avatar
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    98 silverado security light

    the security light on my truck keeps coming on. Every now and then it will throw the code and shut down the fuel pump, whats the best method to stop this from happening?
    98 silverado 4wd 3.73gears,5.7l,headers,under drive pulleys,78mm ported and polished tb, k&n fipk,catback, zz4 cam, roller rockers, lt4 valve springs, 411 swap tuning by me.

    Quote Originally Posted by Redneck Rebel View Post
    fsc demo derby time. Would've been a better disposal system than the Cash4Clunkers BS

  2. #2
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    Re: 98 silverado security light

    You may be able to reprogram the comp to run without it.
    Do you have a chip on your key?
    Don't think my 96 has a security light. Didn't think they did that on trucks in 98 either.

    03 Silverado ECSB, Dmax, Allison, 3.73 G80
    96 Silverado ECSB, 350, 4L60E, 3.73's Powertrax Locker
    05 Cavalier
    74 Corvette Stingray, 350, 4 speed
    49 F-1, flathead 6, 4 speed, 2wd, unknown rear end. Old rust bucket.

  3. #3
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    Re: 98 silverado security light

    Does your security telltale ever flash or does it stay on steady?
    Has your truck ever had a remote start installed?
    Does you trucks security telltale come on while driving?

    This is good reading from a different forum:

    "Vehicle Theft Deterrent (VTD) Description

    Due to component variability, the vehicle theft deterrent (VTD) system must have the learn procedure performed regardless, if the vehicle starts on the first ignition cycle after a VTD repair.

    All codes in the theft deterrent module must be cleared for a relearn.

    The vehicle theft deterrent system is designed in order to prevent vehicle theft by disabling the fuel injectors unless the lock cylinder is correctly engaged by a mechanical key. The theft deterrent system uses the following 4 components for theft prevention:

    The lock cylinder
    The ignition switch
    The body control module (BCM)
    The powertrain control module (PCM)
    When starting the engine, the PCM searches for a password from the BCM through the Class 2 serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. Two modes of tamper detection are provided:

    No password received The engine will start and stall quickly. SECURITY telltale will flash on the instrument panel cluster (IPC) and then stay ON steady.
    Incorrect or disable password received (More than 3 invalid passwords are received) The engine is disabled for at least 10 minutes and the SECURITY telltale will illuminate solid on the IPC during the 10 minutes.
    After the vehicle has passed theft detection, the PCM will continue normal operation.

    Ignition Switch
    The mechanical key and lock cylinder is located in the instrument panel assembly. The electrical switching portion of the assembly is separate from the key and lock cylinder. Both of the components are synchronized and work in conjunction through the action of the actuator rod assembly.

    Passlock™ Lock Cylinder
    The Passlock™ lock cylinder is a locking cylinder that turns a rotating magnet past a stationary hall effect sensor. This action creates the Passlock™ cylinder data. The Passlock™ cylinder data is sent to the body control module (BCM). The Passlock™ lock cylinder is interfaced with the BCM via a 3-wire connection:


    Powertrain Control Module (PCM)
    The Powertrain Control Module (PCM) is located on the lower left side of the instrument panel.

    The PCM communicates with the body control module (BCM) via serial data over the class 2 serial data bus, CKT 1807. When the BCM determines a passed theft condition, the BCM sends a coded password to the PCM. When the PCM receives the correct password, the PCM enables the fuel injection system, allowing the vehicle to operate correctly. The PCM may allow the car to start and quickly stall during a failed theft condition.

    The following conditions may cause the PCM to enter a tamper mode:

    A bad timing cycle
    An incorrect password
    If the BCM does not receive a password within a preset time window, the BCM will enter a short tamper mode. During this mode, the PCM will not allow the car to operate for 4 seconds.

    If the password is incorrect, the PCM will enter the long tamper mode. In the long tamper mode, the following actions will occur:

    The THEFT SYSTEM indicator will flash.
    The fuel injectors will be shut off for approximately 10 minutes.
    Although the vehicle may start, the engine will quickly stall due to a fuel cut-off.

    In the event of an open in the serial data communication between the BCM and the PCM, the following actions occur:

    The PCM will become fail-enabled if the car has already passed theft for that ignition cycle (i.e. the engine is running).
    The PCM may set the diagnostic trouble codes (DTC).
    The THEFT SYSTEM indicator will light continuously.
    The PCM will become fail-enabled for future ignition cycles.
    If a failure occurs in serial data before the ignition cycle, while the PCM is not fail-enabled, the PCM will never receive a valid password in order to enable the continued use of the fuel injectors."

    both of these links are related to gm passlock system
    Last edited by mattillac; 03-30-2008 at 04:33 AM.


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