P1631

DTC P1631

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1631
- Theft Deterrent Fuel Enable Signal Not Correct

Circuit/System Description

The remote control door lock receiver (RCDLR) 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 an ECM with a GM SPO replacement part, the new ECM will learn the incoming fuel enable password immediately upon request.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The ECM receives an incorrect password from the RCDLR.

Action Taken When the DTC Sets

* The vehicle will not start.
* The instrument panel cluster (IPC) will illuminate the SECURITY indicator.
* The PCM will not illuminate the malfunction indicator lamp (MIL).

Conditions for Clearing the 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.


Circuit/System Verification

With a scan tool, verify DTC P1631 is not set.

If DTC is set, Perform the password learn procedure. If DTC resets, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

For replacement, setup, and programming Refer to Programming and Relearning Programming and Relearning