GM Service Manual Online
For 1990-2009 cars only

The theft deterrent module controls the SECURITY indicator lamp. The SECURITY indicator has several operation modes:

    • The SECURITY indicator turns ON for 5 seconds and then turns OFF.
       - This mode occurs when you turn the ignition switch from the OFF to one of the following positions:
   - The RUN position
   - The BULB TEST position
   - The START position
       - This action indicates that an ignition key has the correct resistor pellet code. This also functions as a bulb inspection. The theft deterrent system is in good operating condition.
    • The SECURITY indicator turns ON for 1 minute and then turns OFF while the engine is running.
       - This action indicates that the theft deterrent module detects one of the following key detection circuit malfunctions:
   • A faulty resistor pellet
   • An open
   • A short to the battery or ground
       - The theft deterrent module continues to monitor the key detection circuit constantly after the engine starts. If the malfunction goes away within 1 minute of the malfunction detection, the SECURITY indicator turns OFF and the PASS-Key® II will function as normal.
       - The following actions occur if the malfunction ends within 1 minute of detection:
   • The SECURITY indicator turns OFF.
   • The PASS-Key® II functions normally.
    • The SECURITY indicator turns ON for 3 minutes.
        The SECURITY indicator turns ON for 3 minutes when an ignition key with the wrong resistor pellet code is used to start the engine. This indicates that the 3-minute shut down mode is active. The shut down mode prevents the vehicle from starting.
    • The SECURITY indicator flashes once per second when you turn the ignition switch from the OFF to the RUN position.
       - The flashing continues for as long as the ignition switch remains in the RUN position, without the 3-minute shut down. The engine will not crank during this time.
       - One or more of the following conditions exists:
   • The resistor sensing contacts at the ignition lock cylinder are open or shorted.
   • The key detection circuit is open or shorted to the battery or ground.
   • The ignition key resistor pellet is faulty, damaged or missing.
    • The SECURITY indicator flashes once per second with the engine running.
       - One or more of the following conditions exists:
   • A new unprogrammed theft deterrent module is installed. The theft deterrent module is unable to read the resistor pellet due to a circuit malfunction.
   • The resistor sensing contacts at the ignition lock cylinder are open or shorted.
   • The key detection circuit is open or shorted to the battery or ground.
   • The ignition key resistor pellet is faulty or damaged.
       - When you attempt to start the engine again, the engine will start. The SECURITY indicator flashes during the ignition cycle while the fault is present. This is called the fail-enable mode. The vehicle will not be protected by the PASS-Key® II until the key detection circuit malfunction is corrected. Since the fault occurred while the engine was running, the system has already detected a valid resistor pellet code. The theft deterrent module allows the engine to start until the vehicle is serviced and the malfunction is corrected.
       - Refer to Vehicle Theft Deterrent (VTD) System Check .