P1631

DTC P1631

Circuit Description

The theft deterrent control module sends the fuel enable password to the engine control module (ECM) via the serial data circuit. The ECM verifies the fuel enable password received matches the password stored in memory. If the fuel continue password is correct, the ECM enables the starting and fuel delivery systems. When replacing a ECM with a GM SPO replacement part, the new ECM will learn the incoming fuel enable password immediately upon receipt.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1631 Theft Deterrent Fuel Enable Signal Not Correct

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The ECM receives an incorrect password from the theft deterrent control module.

Actions Taken When the DTC Sets

* The vehicle will not start.
* The instrument panel cluster (IPC) will illuminate the SECURITY indicator.
* The ECM 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

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

Test Description

Step 1 - Step 6:

The numbers below refer to the step numbers on the diagnostic table.
2. Verifies if the condition for setting DTC B3060 is current.
3. To set this code, the password that the ECM has learned does not agree with the password being received from the theft deterrent control module or the ECM did not received the password from the theft deterrent control module. This condition can occur if the theft deterrent control module has been replaced and the Programming Theft Deterrent System Components procedure has not been performed.
5. If the ECM resets the DTC after the programming theft deterrent system components procedure has been performed, the theft deterrent control module is malfunctioning.