Preliminary Inspections
- Visually inspect easily accessible brake system components for
obvious damage and/or leaks which may indicate that the vehicle should not
be driven until further inspections have been completed.
- Inspect the brake master cylinder reservoir fluid level and adjust
only if necessary for brake system road testing. Refer to
Master Cylinder Reservoir Filling
.
- Inspect the tire inflation pressures and adjust as necessary.
- Inspect the tire tread patterns to ensure that they are the same
or very similar, especially per axle.
- Ensure that the vehicle is not loaded unevenly prior to brake
system road testing.
Road Testing Procedure
Caution: Road test a vehicle under safe conditions and while obeying all traffic laws.
Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere
to these precautions could lead to serious personal injury and vehicle damage.
- Start the engine and allow it to idle.
- Check to see if the brake system warning lamp remains illuminated.
- If the brake system warning lamp remains illuminated, DO NOT proceed
to test drive the vehicle until it is diagnosed and repaired. Refer to
Symptoms - Hydraulic Brakes
.
- Select a smooth, dry, clean and level road or large lot that is
as free of traffic and obstacles as possible for brake system low speed road
testing.
- With the transmission in PARK, lightly apply the brake pedal.
Observe both the pedal feel and the pedal travel.
- If the brake pedal apply felt spongy, or the pedal travel was
excessive, DO NOT drive the vehicle until it is repaired.
- If the brake pedal apply did not feel spongy and the pedal travel
was not excessive, proceed to step 8.
- Release and apply the brakes.
- While continuing to apply the brakes, shift the transmission into
DRIVE, release the brakes and allow the engine to idle the vehicle away from
the stopped position. Observe for a slow release of the brake system.
- With the aid of an assistant to observe the vehicle's performance
from outside of the vehicle, drive the vehicle at a low speed and lightly
apply the brakes while driving past the assistant. Have the assistant
observe for brake system noise from the side of the vehicle closest to
them, while you observe both the pedal effort and the pedal travel.
- If the brake pedal apply effort was excessive, or the pedal travel
was excessive, DO NOT continue to test drive the vehicle until it is repaired.
- If the brake pedal apply effort was not excessive and the pedal
travel was not excessive, proceed to step 13.
- Drive the vehicle in the opposite direction, at the same low speed
and lightly apply the brakes while driving past the assistant. Have the assistant
observe for brake system noise from the side of the vehicle closest to
him.
- Drive the vehicle at a low speed and shift the transmission into
NEUTRAL without applying the brakes. Observe for a rapid deceleration in vehicle
speed, indicating possible brake drag.
- Select a smooth, dry, clean and level road that is as free of
heavy traffic as possible for brake system moderate speed road testing.
- Drive the vehicle at a moderate speed. Observe for a pull and/or
incorrect tracking of the vehicle without the brakes applied.
- While continuing to drive the vehicle at a moderate speed, perform
several light applies of the brakes. Observe the pedal effort and the pedal
travel, observe for brake system noise, pulsation and/or brake drag.
- If the brake pedal apply effort was excessive, or the pedal travel
was excessive, DO NOT continue to test drive the vehicle until it is repaired.
- If the brake pedal apply effort was not excessive and the pedal
travel was not excessive, proceed to step 20.
- While continuing to drive the vehicle at a moderate speed, perform
several moderate applies of the brakes. Observe the pedal effort and the pedal
travel, observe for brake system pulsation and/or uneven braking action
- either side to side, or front to rear.
A small amount of vehicle front end dip is expected during a moderate
apply of the brakes.
- If the brake pedal apply effort was excessive, or the pedal travel
was excessive, DO NOT continue to test drive the vehicle until it is repaired.