For 1990-2009 cars

### 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 B3902: Incorrect Immobilizer Identifier Received

### Circuit/System Description

When certain modules are programmed and configured during installation, the module learns a specific immobilizer identifier which is unique to the vehicle. The immobilizer identifier is used to prevent swapping modules between vehicles. The body control module (BCM) is the keeper of the immobilizer identifier. The instrument cluster, electronic brake control module (EBCM), and HVAC control module each learn the immobilizer identifier during their configuration process. During vehicle operation, each of these modules compare their immobilizer identifier to the BCM. If the identifiers match, vehicle starting is allowed. If an immobilizer identifier does not match, vehicle starting is disabled.

### Conditions for Running the DTC

Ignition is in the ACCESSORY or RUN position.

### Conditions for Setting the DTC

An incorrect immobilizer identifier is received by the control module.

### 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 module learns an environment identifier.

### 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

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Perform the Programming and Setup procedure for the concerned control module. Verify the DTC does not reset after programming.

⇒ | If the DTC resets, replace the concerned control module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for Instrument Cluster, body control module and electronic brake control module replacement, setup, and programming