Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- CHECK FOR AN ACTIVE DTC NOTE:
This DTC must be active for the results of this test to be valid.
- Perform any Service Bulletins that may apply.
- Turn the ignition on.
- For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
- With the scan tool, read DTCs and record on the repair order.
- With the scan tool, read and record Environmental Data to help identify the conditions in which the DTC was set.
- With the scan tool, erase all DTCs.
- Start the engine.
- Press and release the brake pedal.
- With the scan tool, read BSCM DTCs.
Did the DTC return?
Yes
- Go To 2
No
- Perform the BSCM INTERMITTENT CONDITION TEST. Refer to: BSCM INTERMITTENT CONDITION .
- CHECK FOR BRAKE PEDAL POSITION (BPP) OR COMMUNICATION RELATED DTCS
- Refer to the recorded DTCs.
Are there any BSCM BPP Sensor or Communication related DTCs present?
Yes
- Perform the applicable diagnostic procedure(s). Refer to: BRAKE SYSTEM CONTROL MODULE (BSCM) - DIAGNOSTIC CODE INDEX .
No
- Go To 3
- Refer to the recorded DTCs.
- ISOLATE AND CHECK THE (B15) BRAKE SIGNAL 1 CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE BSCM HARNESS CONNECTOR
- The ignition must be off when performing a resistance check to find a short between circuits.
- Isolate the circuit by disconnecting the BSCM harness connector and the Body Control Module (BCM) C4 harness connector containing the circuits being tested. At this time leave all in-line connectors connected. Note: Use the wiring diagram as a guide to follow the path of the circuit.
- Connect one lead of the DVOM to the circuit being tested at the BSCM harness connector.
- With the other lead of the DVOM probe all other circuits at the BSCM harness connector.NOTE:
When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.