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 P0703: Torque Converter / Brake Switch Circuit Malfunction

### Circuit/System Description

The body control module (BCM) monitors the stop lamp switch mounted on the brake pedal. The BCM sends a GMLAN serial data message to the engine control module (ECM) indicating the status of the stop lamp switch.

### Conditions for Running the DTC

The engine is ON.

### Conditions for Setting the DTC

• | The ECM receives an invalid brake pedal status GMLAN serial data message from the BCM.

• | This diagnostic runs continuously.

### Action Taken when the DTC Sets

DTC P0703 is a type C Store Only DTC.

### Conditions for Clearing the MIL/DTC

DTC P0703 is a type C Store Only DTC.

### Reference Information

#### Schematic Reference

Cruise Control Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Important: Fix any Brake System related DTCs before using this diagnostic.

Note: This DTC may be stored as a history DTC without affecting the operation of the BCM. Do not replace the BCM if this DTC is stored only as a history DTC and is not retrieved as a current DTC.

Using a scan tool is DTC P0703 current in the ECM?

⇒ | If DTC P0703 is current in the ECM, replace the BCM.

⇒ | If DTC P0703 is not current in the ECM, the system is OK.

### Repair Instructions

Perform the Diagnostic Repair Verification .

Control Module References