GM Service Manual Online
For 1990-2009 cars only

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 P1630: Theft Deterrent Learn Mode Active

Circuit/System Description

When replacing a body control module (BCM), the engine control module/powertrain control (ECM/PCM) must learn the new fuel enable password from the replacement BCM. If the ECM/PCM is replaced with a service replacement part, it is in a functional state to automatically learn the vehicle fuel continue password. If the BCM is replaced, the ECM/PCM must be placed in learn mode so it can learn the new BCM password. This DTC indicates the ECM/PCM is in a functional state to learn the BCM fuel enable password.

Conditions for Running the DTC

The ECM/PCM is in learn mode.

Conditions for Setting the DTC

DTC  P1630 will set any time the ECM/PCM enters learn mode.

Action Taken When the DTC Sets

The security indicator will illuminate.

Conditions for Clearing the DTC

    • A current DTC will be cleared upon a successful engine start after exit of learn mode.
    • A history DTC will be cleared after 100 malfunction-free ignition cycles.

Reference Information

Schematic Reference

Theft Deterrent System Schematics

Connector End View Reference

Theft Deterrent System Connector End Views

Description and Operation

Vehicle Theft Deterrent (VTD) Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

Important: Because of normal system communications between the BCM and ECM/PCM, any theft deterrent B-codes must be diagnosed prior to the diagnosis of P-codes.

Perform the 10-Minute Immobilizer Relearn procedure. Refer to Programming Theft Deterrent System Components. The ECM/PCM should successfully complete the password learn and the vehicle should start.

If the ECM/PCM does not complete the learn or vehicle starting remains disabled, replace the ECM/PCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM/PCM replacement, setup, and programming