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 Descriptors

DTC B0687: Security System Indicator Circuit Low
DTC B0688: Security System Indicator Circuit High

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Security Indicator Control | B0687 | B0687 | B0688 | --

### Circuit/System Description

The security indicator is controlled by the body control module (BCM) based on commands from the immobilizer system or the content theft deterrent (CTD) system. With the ignition OFF, the security indicator is commanded by the CTD system. With the ignition ON, the security indicator is commanded by the immobilizer system.

The security indicator is located in the instrument panel cluster (IPC) and is supplied B+ at all times. When the immobilizer or CTD system requests the indicator be commanded ON, the BCM grounds the security indicator control circuit, illuminating the indicator.

### Conditions for Running the DTC

The security indicator is commanded ON.

### Conditions for Setting the DTC

#### B0687

A short to ground or an open/high resistance is seen on the security indicator control circuit.

#### B0688

A short to voltage is seen on the security indicator control circuit.

### Action Taken When the DTC Sets

Security indicator output is disabled.

### Conditions for Clearing the DTC

• | A current DTC will clear when the fault is no longer present.

• | A history DTC will clear after 40 malfunction-free ignition cycles.

### Reference Information

#### Schematic Reference

Theft Deterrent System Schematics

#### Connector End View Reference

Component Connector End Views

#### 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

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, command the security indicator ON and OFF with a scan tool. The security indicator should turn ON and OFF when changing between the commanded states.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the IPC.
2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 1 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Connect a test lamp between the control circuit terminal 16 and B+.
4. Command the security indicator ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the IPC.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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