Symptom Related Diagnostic Procedures

Brakes

Brake System Symptom Troubleshooting / Rapid brake pad wear, vehicle vibration

Rapid brake pad wear, vehicle vibration (after a long drive), or high, hard brake pedal

NOTICE:
If the brake system indicator is on, do not drive the vehicle. Check the advanced hydraulic booster system Reading and Clearing Diagnostic Trouble Codes.

NOTE: Make sure that the caliper pins are installed correctly. The upper caliper pin and the lower caliper pin are different. If these caliper pins are installed in the wrong location, it will cause vibration, uneven or rapid pad wear, and possibly uneven tire wear. See the front caliper pin location Overhaul.

1. Brake system check:

Brake system check
-1. Check the advanced hydraulic booster system Reading and Clearing Diagnostic Trouble Codes. Make sure the indicators are not turned on.

-2. Drive the vehicle until the brakes drag or until the pedal is high and hard. This can take 20 or more brake pedal applications during an extended test-drive.

-3. With the engine running, raise and support the vehicle, and spin all four wheels by hand.

Is there brake drag at any of the wheels?
-YES- Go to step 2.
-NO- Look for other causes of pad wear, high pedal, or vehicle vibration.

2. AHB system check:

AHB system check
-1. Turn the ignition switch to LOCK (0), press the brake pedal to deplete the advanced hydraulic booster system, then spin the wheels again to check for brake drag.

Is there brake drag at any of the wheels?
-YES- Go to step 3.
-NO- Replace the servo unit Service and Repair.

3. Brake pedal position switch check:

Brake pedal position switch check
-1. Remove the brake pedal position switch, then spin the wheels to check for brake drag.

Is there brake drag at any of the wheels?
-YES- Go to step 4.
-NO- Check the brake pedal position switch adjustment Adjustments and pedal free play Procedures.

4. Master cylinder check:

Master cylinder check
-1. Loosen the hydraulic lines at the master cylinder, then spin the wheels to check for brake drag.

Is there brake drag at any of the wheels?
-YES- Go to step 5.
-NO- Check the master cylinder reservoir for contamination in the brake fluid. If you find contamination, flush the entire brake system of all contaminated fluid, then replace all rubber parts in the brake system that were exposed to contaminated fluid. If the brake fluid is OK, replace the master cylinder Service and Repair.

5. Caliper or wheel cylinder check:

Caliper or wheel cylinder check
-1. Loosen the bleed screws at each caliper or wheel cylinder, then spin the wheels to check for brake drag.

Is there brake drag at any of the wheels?
-YES- Check the master cylinder reservoir for contamination in the brake fluid. If you find contamination, flush the entire brake system of all contaminated fluid, then replace all rubber parts in the brake system that were exposed to contaminated fluid. If the brake fluid is OK, disassemble and repair the caliper or wheel cylinder on the wheel(s) experiencing brake drag.
-NO- Look for and replace any damaged brake lines. If all brake lines are OK, replace the VSA modulator-control unit Service and Repair.