Brake Pedal Assy: Testing and Inspection

NOTE:
^ A preliminary check can be made for brake system integrity. With vehicle stationary and engine running, apply 660 N (150 lb.) pedal force to the brake pedal. If the brake warning light illuminates or the brake pedal contacts some object that prohibits further brake pedal travel, check for cause and correct the condition.

^ This preliminary check should not be used to determine brake pedal travel. Since brake pedal reserve and brake pedal travel are different, the testing procedure for brake pedal travel should be followed closely.

Engine must be off and all vacuum exhausted from the booster before making checks.
1. With ignition off, pump pedal several times to deplete booster vacuum.
2. Using brake pedal force gage, J 28662, hook end of measuring tape over the top edge of the service brake pedal pad.
3. Unreel measuring tape to rim of steering wheel, placing thumb nail at edge of wheel and take reading.
4. While holding tape measure at wheel, press service brake pedal with 445 N (100 lb) force and again note reading. The difference between the two readings is the amount of pedal travel. Pedal travel should not exceed 2.5 inches for a standard brake system. Most low pedal problems are caused by air in lines, which means the system must be bled. It may be necessary to bleed the system several times at each fitting. If pedal travel exceeds specification, there may still be some air in the system. Other less frequent causes of excessive pedal travel are incorrect push rod length, an improperly adjusted parking brake, rear brake piston actuators not adjusting, shoes requiring relining, front or rear hydraulic system leakage and tapered or unevenly worn linings.