Download Brake System Test Brake pedal sinks/fades when braking 1. Start the engine, and let it warm up to operating temperature. 2. Attach a 50 mm (2 in.) piece of masking tape along the bottom of the steering wheel, and draw a horizontal reference mark across it. 3. With the transmission in the P or N position, press and hold the brake pedal lightly (about the same pressure needed to keep an A/T-equipped vehicle from creeping), then release the parking brake. 4. While still holding the brake pedal, hook the end of the tape measure behind it. Then pull the tape up to the steering wheel, noting where the tape measure lines up with the reference mark you made on the masking tape. 5. Apply steady pressure to the brake pedal for 3 minutes. 6. Watch the tape measure. • If it moves less than 10 mm (3/8 in.), the master cylinder is OK. • If it moves more than 10 mm (3/8 in.) replace the master cylinder. NOTE: If the brake pedal sinks more than 10 mm (3/8 in.) in 3 minutes, the master cylinder is faulty. A slight change in pedal height when the A/C compressor cycles on and off is normal. (The A/C compressor load changes the vacuum available to the brake booster.) Symptom Troubleshooting Rapid brake pad wear, vehicle vibration (after a long drive), or high, hard brake pedal NOTE: Make sure that the caliper pins are installed correctly. The upper and lower caliper pins are different. If the top and bottom caliper pins are installed in the wrong location, it will cause uneven tire wear, vibration, and or uneven or rapid pad wear. For proper caliper pin location (see page 19-16).