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: Brake Switch Circuit 2

### Circuit/System Description

The body control module (BCM) monitors the brake pedal position sensor. When the brake pedal is applied, the BCM detects a predetermined voltage signal. The BCM sends a serial data message to the engine control module (ECM) indicating the status of the stop lamps.

### Conditions for Running the DTC

The engine is ON.

### Conditions for Setting the DTC

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

• | This diagnostic runs continuously.

### Actions Taken When the DTC Sets

• | The cruise control system is disabled.

• | The malfunction indicator lamp (MIL) will not illuminate.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

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

### Reference Information

#### Schematic Reference

Cruise Control Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cruise Control 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. Verify that DTC P0572 or P0573 is not set.

⇒ | If DTC is set, refer to Diagnostic System Check - Vehicle.

2. Verify that DTC P0703 is not set.

⇒ | If DTC is set, replace the BCM. Clear the DTC and road test the vehicle. If DTC resets, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Brake Pedal Position Sensor Replacement

• | Control Module References for BCM or ECM replacement, setup and programming