Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | 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 CorrectCircuit/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. |
Reference Information
Schematic Reference
Connector End View Reference
Master Electrical Component List
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
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.
Control Module References for replacement, setup, and programming
