GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Malibu 🢒 Engine 🢒 Cruise Control 🢒 DTC P0703

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 00: Brake Switch Circuit 2

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
    • The Cruise Control System is disabled.
    • The ECM stores the DTC information into memory when this diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • All of the scan tool cruise control function switch parameters are set to Off.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM 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
    • If a BCM has been replaced, the brake pedal position (BPP) sensor must be calibrated. Refer to Brake Pedal Position Sensor Calibration .
    • Repair any Brake System related DTCs before performing this diagnostic table.
    • 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 .

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Data Communication Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

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. Do not replace the BCM or ECM 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 .
    2. ⇒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.
    3. ⇒If DTC P0703 sets as current in the ECM, replace the ECM.
    ⇒If DTC P0703 does not set in the ECM, the system is OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming