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.

### Circuit/System Description

The main immobilizer function is performed as an interaction between several modules. The process that determines whether the engine may be engaged or not consists of several steps. When the immobilizer is active the indicator in the dashboard is flashing.

### 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 Testing

1. Ignition OFF, disconnect the harness connector at the B10B Light/Sunload Sensor - Ambient.
2. Test for less than 5 Ω between the ground circuit terminal 6 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Disconnect the harness connector X1 at the K9 Body Control Module. Test for less than 0.3 V at the signal circuit terminal 1 at the B10B Light/Sunload Sensor - Ambient and ground.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage.

4. Test for less than 5 Ω between the signal circuit terminal 1 at the B10B Light/Sunload Sensor - Ambient and the signal circuit terminal 21 (X1) at the K9 Body Control Module.

⇒ | If greater than the specified range, test the signal circuit for an open/high resistance.

⇒ | If the circuit tests normal, replace the B10B Light/Sunload Sensor - Ambient.

5. If all circuit test normal, replace the K9 Body Control Module.

### Repair Instructions

Perform the Diagnostic Repair Verificationafter completing the diagnostic procedure.

Control Module References for body control module (BCM) replacement, setup, and programming