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DTC B2955

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 B2955: Security Sensor Data Circuit Malfunction

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+

B2955

B2955

--

--

Serial Data

B2955

B2955

B2955

B2955

Low Reference

--

B2955

--

--

Circuit/System Description

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energised by the exciter coils surrounding the ignition lock cylinder. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.

Conditions for Running the DTC

Ignition is in the Accessory or Run position.

Conditions for Setting the DTC

The BCM is unable to measure the ignition key transponder value.

Action Taken When the DTC Sets

    • Vehicle starting will be disabled.
    • The security indicator in the instrument cluster will be illuminated. A service message will be displayed in the driver information centre.

Conditions for Clearing the DTC

    • A current DTC will be cleared when the BCM detects a valid transponder value from the ignition key.
    • A history DTC will be cleared after 100 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
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Inspect all available vehicle keys that they are correct vehicle keys.
  2. If not a correct vehicle key, replace the key.
  3. Ignition OFF, disconnect the harness connector at the K89 Immobilizer Control Module and disconnect the harness connector X3 at the K9 Body Control Module. Test for infinite resistance between the signal circuit listed below and ground.
  4. • K9 Body Control Module terminal 1 X3
    • K9 Body Control Module terminal 2 X3
    • K9 Body Control Module terminal 3 X3
    If less than the specified range, test the appropriate signal circuit for a short to ground.
  5. Test for less than 0.3 V between the signal circuit listed below and ground:
  6. • K9 Body Control Module terminal 1 X3
    • K9 Body Control Module terminal 2 X3
    • K9 Body Control Module terminal 3 X3
    If greater than the specified range, test the appropriate signal circuit for a short to voltage.
  7. Test for less than 5 Ω between the signal circuit terminal listed below at the K9 Body Control Module and the signal circuit terminal listed below at the K89 Immobilizer Control Module.
  8. • K9 Body Control Module terminal 1 X3 and K89 Immobilizer Control Module terminal 1
    • K9 Body Control Module terminal 2 X3 and K89 Immobilizer Control Module terminal 2
    • K9 Body Control Module terminal 3 X3 and K89 Immobilizer Control Module terminal 3
    If greater than the specified range, test the appropriate signal circuit for an open/high resistance.
  9. If all circuits test normal, replace the K89 Immobilizer Control Module and verify that the customer concern is not still present.
  10. If the customer concern is still present, replace the K9 Body Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Replacing Keys
    • Control Module References for control module replacement, setup and programming
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved