Brake Booster Test - Honda 2002 Accord Manual

Brake Booster Test
Functional Test
1. With the engine stopped, press the brake pedal
several times to deplete the vacuum reservoir, then
press the pedal hard and hold it for 15 seconds. If
the pedal sinks, either the master cylinder is
bypassing internally, or the brake system (master
cylinder, lines, modulator, proportioning valve, or
caliper) is leaking.
2. Start the engine with the pedal pressed. If the pedal
sinks slightly, the vacuum booster is operating
normally. If the pedal height does not vary, the
booster or check valve is faulty.
3. With the engine running, press the brake pedal
lightly. Apply just enough pressure to hold back
automatic transmission creep. 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 booster.)
Leak Test
Booster Check Valve Test
1. Disconnect the brake booster vacuum hose (check
valve built-in) (A) at the booster (B).
2. Start the engine, and let it idle. There should be
vacuum available. If no vacuum is available, the
check valve is not working properly. Replace the
brake booster vacuum hose and check valve, and
retest.
1. Press the brake pedal with the engine running, then
stop the engine. If the pedal height does not vary
while pressed for 30 seconds, the vacuum
booster is OK. If the pedal rises, the booster is
faulty.
2. With the engine stopped, press the brake pedal
several times using normal pressure. When the
pedal is first pressed, it should be low. On
consecutive applications, the pedal height should
gradually rise. If the pedal position does not vary,
check the booster check valve.
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