GM Service Manual Online
For 1990-2009 cars only

Refer to one of the following Theft Deterrent System schematics:

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Theft Deterrent Control Module


Object Number: 623196  Size: FS
Master Electrical Component List
Vehicle Theft Deterrent (VTD) Description and Operation
Door Lock Actuators
License Plate Lamps, Park Lamp Relay
Horns
Serial Data Class 2
Battery Feed to the Fuse Block-Underhood
IGN SW (Fuse Block-Rear)
IGN SW Fuse (Fuse Block-Rear)
IGN SW Fuse (Fuse Block-Rear)
G201 (2 of 2)
G201 (2 of 2)
    • 

Door Lock Actuators


Object Number: 623197  Size: FS
Master Electrical Component List
Content Theft Deterrent (CTD) Description and Operation
Theft Deterrent Control Module
Serial Data Class 2

Circuit Description

When an ignition key is inserted into the ignition lock cylinder, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the theft deterrent controller module . The theft deterrent controller module then compares this value to a value stored in memory (learned key code). If the value is correct the theft deterrent controller module sends the enable password via the class 2 serial data circuit to the PCM.

Conditions for Running the DTC

The ignition switch must be in RUN. The theft deterrent controller module cannot have DTC B1327 set as a current DTC.

Conditions for Setting the DTC

If the code from the ignition key does not match one stored in memory, the theft deterrent controller module sets this DTC. This code indicates the use of a key with a transponder that has not been learned by the theft deterrent controller module. The vehicle considers this to be a theft attempt.

Action Taken When the DTC Sets

  1. The theft deterrent controller module sends a class 2 message containing a disable password to the PCM.
  2. The vehicle will not start.
  3. The theft deterrent controller module sends a class 2 message to the instrument cluster to flash the SECURITY indicator.

Conditions for Clearing the MIL/DTC

The theft deterrent controller module clears the current status of the DTC when it senses a valid, memorized, key code from the ignition key (transponder).

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. To set this code, a key with a working transponder was read by the theft deterrent controller module. For that key to operate the vehicle, a 10 Minute or 30 Minute Re-Learn Procedure must be performed.

Step

Action

Yes

No

1

Did you perform A Diagnostic System Check - Theft Deterrent ?

Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

Perform the theft deterrent controller Module learn Procedure. Refer to Programming Replacement Keys, Ignition Cylinder, or Powertrain Control Module .

Important: If a 10 Minute or 30 Minute Re-Learn Procedure is performed, all keys not learned at that time will be erased and will not be recognized. Perform the Quick Learn Procedure on all keys or instruct the customer how to perform the Quick Learn Procedure.

Is the procedure complete?

Go to Step 3

--

3

  1. Use a scan tool in order to clear the DTC's.
  2. Attempt to start the vehicle.

Does the DTC reset?

Go to Step 2

System OK