For 1990-2009 cars only
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 CircuitCircuit/System Description
The body control module (BCM) monitors the stop lamp switch, mounted on the brake pedal. The BCM sends a serial data message to the engine control module (ECM) indicating the status of the stop lamp switch.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The cruise switch 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 malfunction indicator lamp (MIL) will not illuminate. |
| • | The cruise control system is disabled. |
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
Connector End View Reference
Description and Operation
Cruise Control Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Repair any brake system related DTCs before performing this diagnostic.
- Verify that DTC P0572 or P0573 is not set as current.
- Verify that DTC P0703 is not set.
| ⇒ | If the brake system or brake lights do not operate properly, refer to DTC P0572 or P0573. |
| ⇒ | If DTC P0703 is set as current, replace the BCM. Clear the DTC and road test the vehicle. If DTC P0703 resets, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM or ECM replacement, setup, and programming
