Circuit Description
The electronic brake control module (EBCM) monitors the brake pedal position 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) and to the engine control module (ECM) indicating the status of the stop lamps.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0703 Brake Switch Circuit 2
Conditions for Running the DTC
The engine is ON.
Conditions for Setting the DTC
| • | The TCM or the ECM 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 or the ECM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The TCM or the ECM records the operating conditions at the time the diagnostic fails. The TCM or 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
| • | Repair any brake system related DTCs before performing this diagnostic table. |
| • | If an EBCM has been replaced, the brake pedal position (BPP) sensor must be calibrated. Refer to Brake Pedal Position Sensor Calibration in Lighting Systems. |
| • | This DTC may be stored as a history DTC without affecting the operation of the EBCM. If stored only as a history DTC and not retrieved as a current DTC, do not replace the EBCM. |
| • | If this DTC is retrieved as both a current and a history DTC, replace the EBCM. |
| • | 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.
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This step is performed in order to confirm that DTC P0703 is current within the TCM or the ECM.
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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 to Antilock Brake System Connector End Views in Antilock Brake System | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Is DTC P0703 current in the transmission control module (TCM) or the engine control module (ECM)? | 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 to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 | Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
