From 09'-12' FSM, but should still apply for common brake systems. Hope it helps.
Brake System Test
1. Start the engine, and let it warm up to operating temperature.
2. Attacha 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 than10 mm(3/8 in.), the master cylinder is OK.
• If it moves more than10 mm(3/8 in.) replace the master cylinder.
NOTE: If the brake pedal sinks more than10 mm(3/8 in.)in3 minutes, the master cylinder is faulty. A slight change in pedal height when the A/C compressor cycles onandoff is normal. (The A/C compressor load changes the vacuum available to the brake booster.)
Brake Booster Test
1. Withthe engine stopped, press the brake pedal several times to deplete the vacuum reservoir, then press the brake pedal hard, and hold it for 15 seconds. If the brake pedal sinks, either the master cylinder is bypassing brake fluid internally, or the brake system(master cylinder, lines, modulator, or caliper)is leaking.
2. Start the engine withthe brake pedal pressed. If the brake pedal sinks slightly, the vacuum booster is operating normally. If the brake pedal height does notvary, perform the leak test.
3. With the engine running, press the brake pedal lightly, and shift the transmission to the D position. Apply just enough pressure to hold back automatic transmission creep. If the brake pedal sinks more than10 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 loadchanges the vacuumavailable tothe booster.)