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 provide an overview of each diagnostic category.

### Circuit/System Description

The security indicator acts as a status indicator for the content theft deterrent (CTD) system when the ignition if OFF and a fault indicator for the immobilizer system with the ignition ON. When either the body control module (BCM) or theft deterrent module (TDM) requires the security indicator to be illuminated, a serial data message is sent to the instrument panel cluster (IPC), which will illuminate the indicator.

### Reference Information

#### Schematic Reference

Theft Deterrent System Schematics

#### Connector End View Reference

Instrument Cluster Schematics

#### Description and Operation

Content Theft Deterrent (CTD) Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

### Circuit/System Verification

Ignition ON, perform the scan tool IPC display test. The security indicator illuminate when IPC display is commanded ON.

### Circuit/System Testing

1. Ignition OFF, disconnect the C3 harness connector at the BCM.
2. Ignition ON, verify the security indicator is not illuminated.

⇒ | If indicator is illuminated, test the circuit for a short to ground. If circuit tests normal, relpace the IPC.

3. Ignition OFF, install a 3 amp fused jumper wire between the control circuit terminal 7 and ground.
4. Ignition ON, verify the security indicator is illuminated.

⇒ | If indicator does not illuminate, test the circuit for an open/high resistance. If circuit tests normal, replace the IPC.

5. If all circuits test normal, replace the BCM

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for IPC and BCM replacement, setup and programming.