Diagnostic Instructions
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 class 2 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 class 2 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. |
| • | 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
Important: Repair any brake system related DTCs before performing this diagnostic.
| • | 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. |
Reference Information
Schematic Reference
Exterior Lights Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
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.
Important: 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.
- 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. |
- 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, 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.
