Circuit Description
The electronic brake control module (EBCM) monitors the brake pedal position (BPP) sensor. When the brake pedal is applied, the EBCM detects a predetermined voltage signal. The EBCM sends a class 2 serial data message to the transmission control module (TCM) indicating the status of the stop lamps. The TCM then sends a GMLAN serial data signal to the engine control module (ECM) indicating that the brake pedal has been applied.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The TCM receives an invalid brake pedal status class 2 serial data message from the EBCM. |
| • | This diagnostic runs continuously. |
Action Taken When the DTC Sets
| • | The cruise control system is disabled. |
| • | The TCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | 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
| • | 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 an EBCM has been replaced, the BPP sensor must be calibrated. Refer to Brake Pedal Position Sensor Calibration Description and Operation 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.
-
This step is performed in order to confirm that DTC P0703 is current within the TCM.
-
This step is performed in order to correct a BPP sensor that must be calibrated, possibly due to an EBCM replacement or for a BPP sensor that is out of adjustment.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Antilock Brake System Connector End Views in Antilock Brake System | |||
1 |
Important: Repair all DTCs related to the stop lamps and to the brake system before performing this table. Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | |
Is DTC P0703 current in the transmission control module (TCM)? | Go to Step 3 | Go to Diagnostic Aids | |
Does the DTC reset? | Go to Step 4 | System OK | |
4 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 |
Important: The BPP sensor must be calibrated after replacement. Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
