P0703

DTC P0703

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 00
- 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 GMLAN serial data message to the engine control module (ECM) / powertrain control module (PCM) indicating the status of the stop lamps.

Conditions for Running the DTC

The engine is ON.

Conditions for Setting the DTC

* The ECM/PCM receives an invalid brake pedal status GMLAN serial data message from the BCM.
* This diagnostic runs continuously.

Action Taken When the DTC Sets

* The Cruise Control System is disabled.
* The ECM/PCM stores the DTC information into memory when this diagnostic runs and fails.
* The malfunction indicator lamp (MIL) will not illuminate.
* The ECM/PCM records the operating conditions at the time the diagnostic fails. The ECM/PCM stores this information in the Failure Records.

Conditions for Clearing the DTC

* A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
* A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
* Use the scan tool in order to clear the DTC.

Diagnostic Aids

Important: Repair any brake system related DTCs before performing this diagnostic.

* If a BCM has been replaced, the brake pedal position (BPP) sensor must be calibrated. Refer to Brake Pedal Position Sensor Calibration.
* This DTC may be stored as a history DTC without affecting the operation of the ECM. If stored only as a history DTC and not retrieved as a current DTC, do not replace the BCM or ECM.
* If this DTC is retrieved as both a current and a history DTC, replace the ECM.
* For an intermittent condition, Refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics

Circuit/System Verification

Ignition ON, observe for proper operation of the brake system including the brake lights. Refer to Exterior Lighting Systems Description and Operation.

Circuit/System Testing

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

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

1. Ignition ON, perform the brake pedal position (BPP) sensor calibration procedure and verify the BPP is calibrated properly. Refer to Brake Pedal Position Sensor Calibration.

• If the BPP will not calibrate properly, replace the BPP.

2. Cycle the ignition, apply and release the brake pedal. Using a scan tool, check for DTC P0703 in the ECM.

• If DTC P0703 sets as current in the ECM/PCM, replace the ECM/PCM.
• If DTC P0703 does not set in the ECM/PCM, the system is OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Brake Pedal Position Sensor Replacement
* Programming and RelearningProgramming and Relearning