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Security Indicator Inoperative > < Symptoms - Immobilizer

Astra J

DTC P1629

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 P1629:  Immobilizer Fuel Enable Signal Not Received

Circuit/System Description

The body control module (BCM) sends the prerelease password to the engine control module (ECM) via the serial data circuit. The ECM then sends a challenge to the BCM. Both the ECM and BCM perform a calculation on this challenge. If the calculated response from the BCM equals the calculation performed by the ECM, the ECM will allow vehicle starting.

Conditions for Running the DTC

Ignition is in the ACCESSORY or RUN position.

Conditions for Setting the DTC

The ECM receives an incorrect prerelease password from the BCM.

Action Taken When the DTC Sets

    •  The security indicator in the instrument cluster will illuminate.
    •  Vehicle starting will be disabled.

Conditions for Clearing the DTC

    •  A current DTC P1629 will be cleared when a correct fuel enable password is received.
    •  A history DTC will be cleared after 40 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.

Reference Information

Schematic Reference

Immobilizer Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Immobilizer Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Wiring Repairs


Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Note:  Because of normal system communications between the BCM and ECM, any immobilizer B-codes must be diagnosed prior to the diagnosis of P-codes.

Perform the Immobilizer Relearn procedure. Refer to Immobilizer System Component Programming . The ECM should successfully complete the password learn and the vehicle should start.

⇒ If the ECM does not complete the learn or vehicle starting remains disabled, replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup and programming

Security Indicator Inoperative > < Symptoms - Immobilizer