GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The theft deterrent control module produces the theft deterrent fuel enable signal when ignition is ON and the proper transponder key value is detected. The powertrain control module (PCM) monitors the fuel enable signal during crank. If the proper signal is present on the class 2 serial data circuit, the PCM enables the fuel delivery in order to allow the engine to start. If the PCM is replaced, the replacement PCM should learn the password within a few seconds after the ignition is turned ON. DTC P1630 is an information code indicating that the PCM is ready to learn the theft deterrent password. The engine starts and continues to run with DTC P1630 set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 1630 Theft Deterrent Learn Mode Active

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The PCM remains in theft deterrent password learn mode for more than 2 seconds.

Actions Taken When the DTC Sets

    • The PCM sends a serial data message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
    • The PCM will not illuminate the malfunction indicator lamp (MIL).
    • The PCM will store conditions which were present when the DTC set as failure records data only. This information will not be stored as freeze frame data.

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

A replacement PCM is in a functional state to learn the password from the theft deterrent control module. If the theft deterrent control module is replaced, the PCM must be placed in password learning mode to relearn the new password. Once learned, the password becomes permanent information that remains with the vehicle. The loss of PCM battery or ignition voltage does not affect the programmed password information. Refer to Programming Theft Deterrent System Components .

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 Programming Theft Deterrent System Components

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information