P0703

DTC P0703

Circuit Description

The body control module (BCM) monitors the BPP sensor and sends brake signals to the transmission control module (TCM) via a discreet circuit indicating the status of the stop lamps. The BCM also sends brake signals via the GMLAN serial data circuit to the TCM indicating the status of the stop lamps. When the TCM detects a missing or an invalid brake signal from the BCM, DTC P0703 sets in the TCM. An invalid brake signal may be a result of a signal mismatch between the stop lamp discreet circuit and the GMLAN serial data circuit from the BCM.

Conditions for Running the DTC

^ The ignition is ON.

Conditions for Setting the DTC

^ The TCM detects a missing or invalid brake signal from the BCM.
^ This diagnostic runs continuously.

Action Taken When the DTC Sets

^ Autograde braking inhibited.
^ The cruise control system is disabled.
^ The TCM stores the DTC information into memory when the diagnostic runs and fails.
^ The TCM records the operating conditions at the time the diagnostic fails. The TCM stores this information in the Failure Records.

Conditions for Clearing the MIL/DTC

^ The DTC becomes history when the fault is no longer present.
^ A History DTC clears after 100 malfunction free ignition cycles.
^ 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 in Lighting System.
^ This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
^ For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers located in the diagnostic table.

2. This step is performed in order to confirm that DTC P0703 is current within the ECM.
3. This step is performed in order to correct a BPP sensor that must be calibrated, possibly due to a BCM replacement or for a BPP sensor that is out of adjustment.