Component Tests and General Diagnostics

Brake System Inspection and Test





Inspect the brake system components listed. Repair or replace any parts that are leaking or damaged.

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 inch) piece of masking tape along the bottom of the steering wheel, and draw a horizontal reference mark across it.
3. With the transmission in Neutral, 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 inch), the master cylinder is OK.
^ If it moves more than 10 mm (3/8 inch), replace the master cylinder.

NOTE: If the brake pedal sinks more than 10 mm (3/8 inch) 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.)