Ford 2003 Mustang Workshop Manual page 95

condition. It may not always be necessary to follow a pinpoint test to its conclusion. Carry out only the
steps necessary to correct the condition. Then, test the system for normal operation. Sometimes, it is
necessary to remove various vehicle components to gain access to the component requiring testing.
Reinstall all components after verifying system operation is normal.
PINPOINT TEST A: BRAKE VIBRATION/SHUDDER
A1 ROAD TEST THE VEHICLE—LIGHT BRAKING
Check that the wheel and tires are correct for the vehicle.
Inspect the tires for abnormal wear patterns.
Road test the vehicle. Warm the brakes by slowing the vehicle
a few times from 80–32 km/h (50 to 20 mph) using light braking
applications. At highway speeds of 89–97 km/h (55-60 mph),
apply the brake using a light pedal force.
Is there a vibration/shudder felt in the steering wheel, seat
or brake pedal?
A2 ROAD TEST THE VEHICLE—MODERATE TO HEAVY
BRAKING
Road test the vehicle. At highway speeds of 89–97 km/h (55-60
mph), apply the brake using a moderate to heavy pedal force.
Is there a vibration/shudder?
A3 NORMAL ACTUATION OF THE ABS SYSTEM DIAGNOSIS
During moderate to heavy braking, noise from the hydraulic
control unit (HCU) and pulsation in the brake pedal can be
observed. Pedal pulsation coupled with noise during heavy
braking or on loose gravel, bumps, wet or snowy surfaces is
acceptable and indicates correct functioning of the ABS
system. Pedal pulsation or steering wheel nibble, (frequency is
proportioned to the vehicle speed) indicates a concern with a
brake or suspension component.
Is the vibration/shudder vehicle speed sensitive?
A4 APPLICATION OF THE PARKING BRAKE
NOTE: Begin at the front of the vehicle unless the vibration or
shudder has been isolated to the rear.
This test is not applicable to vehicles with drum-in-hat type
parking brakes. For vehicles with drum-in-hat parking brakes,
proceed to the next test. For all other vehicles, apply the
parking brake to identify if the problem is in the front or rear
brake. At highway speeds of 89–97 km/h (55-60 mph), lightly
apply the parking brake until the vehicle slows down. Release
the parking brake immediately after the test.
Is there a vibration/shudder?
A5 CHECK THE FRONT WHEEL BEARINGS
Check the front wheel bearings. Refer to
in this section.
Are the wheel bearings OK?
Test Step
Wheel Bearing Check
Result / Action to Take
Yes
GO to A4 .
No
GO to A2 .
Yes
For vehicles with ABS,
GO to A3 . For vehicles
with standard brakes,
GO to A4 .
No
Vehicle is OK. VERIFY
condition with customer.
TEST the vehicle for
normal operation.
Yes
GO to A5 .
No
The brake system is
operating correctly.
Yes
GO to A7 .
No
GO to A5 .
Yes
GO to A6 .