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Vauxhall Workshop Service and Repair Manuals

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DTC B3031 > < DTC B3055

Astra J

DTC P1677

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 P1677:  Immobilizer System Disabled

Circuit/System Description

The body control module (BCM) sends the security code 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 is in reset state or is not programmed properly.

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 will be cleared when the ECM is programmed properly.
    •  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

Immobiliser Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Immobiliser 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 immobiliser B-codes must be diagnosed prior to the diagnosis of P-codes. See Diagnostic Trouble Code List.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Perform the Immobiliser Relearn procedure. Refer to Immobiliser System Component Programming .

⇒ 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

DTC B3031 > < DTC B3055