The body control module (BCM) applies a ground through the brake pedal position sensor low reference circuit to the brake pedal position sensor (BPP). The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the BPP. When the brake pedal is being applied, the BPP then sends a variable voltage through the brake sensor signal circuit to the BCM. The BCM then applies a signal to the brake signal circuit to the engine control module (ECM) and transmission control module (TCM).

The ignition is ON.

The BCM detects a short to ground on the brake signal circuit.

The ECM and TCM will not function correctly.

The BCM clears these codes from current when the fault is removed from the system.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Ignition ON, press and release the brake pedal. The stop lamps should illuminate then go out.

1. Ignition OFF, disconnect the harness connector at the ECM, and TCM.
2. Connect a DMM at the ECM, between the brake signal circuit and the positive terminal of the battery.
3. Ignition ON, test for less than 0.1 volt

⇒	If greater than the specified range, test the brake signal circuit for a short to ground. If the circuit/connections test normal, replace the BCM.

4. Leave the DMM connected, connect the TCM harness connector.
5. Ignition ON, test for less than 0.1 volt

⇒	If greater than the specified range, replace the TCM

6. If the voltage is correct and all circuits/connections test normal, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.