Power Brake Assist: Testing and Inspection

Booster Operation Inspection
There are two ways to perform this inspection, with and without a tester. Ordinarily, it is possible to roughly determine its condition without using a tester.

NOTE: For this check, make sure that no air is in hydraulic line.

Check Air Tightness
1. Start engine.
2. Stop engine after running for 1 - 2 minutes.
3. Depress brake pedal several times with the same load as in ordinary braking and observe pedal travel. If pedal goes down deep the first time but its travel decreases as it is depressed the second and more times, air tightness is obtained.








4. If pedal travel doesn't change, air tightness isn't obtained.

NOTE: If defective, inspect vacuum lines and sealing parts, and replace any faulty part. When this has been done, repeat the entire test.








Check Operation
1. With engine stopped, depress brake pedal several times with the same load and make sure that pedal travel doesn't change.





2. Start engine while depressing brake pedal. If pedal travel increases a little, operation is satisfactory. But no change in pedal travel indicates malfunction.





Check Air Tightness Under Load
1. With engine running, depress brake pedal. Then stop engine while holding brake pedal depressed.








2. Hold brake pedal depressed for 30 seconds. If pedal height does not change, condition is good. But it isn't if pedal rises.