Preliminary Brake Check
- Check condition of tires and wheels. Damaged wheels and worn, damaged, or under-inflated tires can cause pull, shudder, vibration, and a condition similar to grab.
- If complaint was based on noise when braking, check suspension components. Jounce front and rear of vehicle and listen for noise that might be caused by loose, worn or damaged suspension or steering components.
- Inspect brake fluid level and condition. Note that the brake reservoir fluid level will decrease in proportion to normal lining wear. Also note that brake fluid tends to darken over time. This is normal and should not be mistaken for contamination.
- If fluid level is abnormally low, look for evidence of leaks at calipers, wheel cylinders, brake lines, master cylinder, and Hydraulic Control Unit (HCU).
- If fluid appears contaminated, drain out a sample to examine. System will have to be flushed if fluid is separated into layers, or contains a substance other than brake fluid. The system seals, cups, hoses, master cylinder, and HCU will also have to be replaced after flushing. Use clean brake fluid to flush the system.
- Check parking brake operation. Verify free movement and full release of cables and lever/pedal. Also note if vehicle was being operated with parking brake partially applied.
- Check brake pedal operation. Verify that pedal does not bind and has adequate free play. If pedal lacks free play, check pedal and power booster for loose or binding condition. Do not road test until condition is corrected.
- Check booster vacuum check valve and hose.
- If components checked appear OK, road test the vehicle.