GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The theft deterrent module (TDM) produces the theft deterrent fuel enable password when ignition is ON and the proper transponder key value is detected. The powertrain control module (PCM) monitors the fuel enable password. If the proper password is present on the serial data circuit, the PCM enables the fuel delivery in order to allow the engine to start. If the PCM detects an incorrect password, vehicle theft deterrent (VTD) system failure or attempted vehicle theft, DTC P1631 is set. During this condition, the PCM disables fuel delivery, NOT allowing the engine to start.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The PCM detects an incorrect password from the TDM.

Action Taken When the DTC Sets

    • The vehicle will not start.
    • The PCM sends a serial data message to the body control module (BCM) to illuminate the SECURITY indicator.
    • The PCM will not illuminate the malfunction indicator lamp (MIL).

Conditions for Clearing the MIL/DTC

    • A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using a scan tool.

Diagnostic Aids

DTC P1631 indicates that the PCM has detected an incorrect fuel enable password from the TDM. This condition can occur if an incorrect key is being used when attempting to start the vehicle or if the TDM has been replaced and the PCMs password learn function has not been enabled.

Test Description

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

  1. Verifies if the condition for setting DTC B3060 is present.

  2. To set this code, the password that the PCM has learned does not agree with the password being received from the TDM. This condition can occur if the TDM has been replaced and the programming theft deterrent system components procedure has not been performed.

  3. If the PCM resets the DTC after the programming theft deterrent system components procedure has been performed, the theft deterrent control module is malfunctioning.

Step

Action

Yes

No

Schematic Reference: Theft Deterrent System Schematics

Connector End View Reference: Theft Deterrent System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Is DTC B3060 set as a current code?

Go to DTC B3060

Go to Step 3

3

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

Perform the Programming Theft Deterrent System Components procedure. Refer to Programming Theft Deterrent System Components .

Is the procedure complete?

Go to Step 4

--

4

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 5

System OK

5

Important: 

   • If original vehicle keys are to be reused, perform the TDM setup prior to TDM replacement. Refer to Programming Theft Deterrent System Components .
   • If new vehicle keys are being used, continue with this step.

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

Replace the TDM. Refer to Theft Deterrent Module Replacement .

Did you complete the replacement?

Go to Step 6

--

6

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK