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.
Circuit Description
Proper operation of the traction control system (TCS) is highly dependent on the ability to apply brake pressure to a selected wheel, through the brake pressure modulator valve (BPMV), as commanded by the electronic brake control module (EBCM). The EBCM may not be able to detect certain mechanical failures that may cause the TCS to perform poorly. This diagnostic procedure is designed to help diagnose concerns of excessive wheel slip or dragging brakes during acceleration, which may occur without the presence of any DTCs.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review the system Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Anti-Lock Brake System |
| 2 |
|
Go to Step 8 | Go to Step 3 |
| 3 | Diagnose any hydraulic brake symptoms exhibited by the vehicle. Refer to Symptoms - Hydraulic Brakes
. Did you find and correct a concern? |
Go to Step 8 | Go to Step 4 |
| 4 |
|
Go to Step 6 | Go to Step 5 |
| 5 |
IMPORTANT:
For 2 wheel drive vehicles, it is not necessary to perform a front wheel apply if the only concern is TC poor performance. Perform brake pressure application testing. Refer to Brake Pressure Modulator Valve Hydraulic Testing .Did either of the TC isolation valve tests fail? |
Go to Step 6 | System OK |
| 6 | Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve (BPMV) Replacement (w/JL4) or Brake Pressure Modulator Valve (BPMV) Replacement (w/o JL4) . Did you complete the replacement? |
Go to Step 7 | - |
| 7 | Use the scan tool to perform all of the available BPMV hydraulic tests. Refer to Brake Pressure Modulator Valve Hydraulic Testing . Do the hydraulic tests show the system to be functioning normally? |
Go to Step 8 | Go to Step 2 |
| 8 | Test drive the vehicle to verify that the concern has been corrected. Does the TCS operate normally? |
System OK | Go to Step 2 |
NO RELATED
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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.