Initial Inspection and Diagnostic Overview
PRELIMINARY CHECKSWARNING: Use of any other than approved DOT 3 brake fluid will cause permanent damage to brake components and will render the brakes inoperative.
WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes with running water for 15 minutes. Get medical attention if irritation persists. If taken internally, drink water and induce vomiting. Get medical attention immediately.
CAUTION: Do not spill brake fluid onto painted surfaces. If spilled, wipe up immediately.
NOTE: Always check the fluid level in the brake master cylinder reservoir before performing the test procedures. If the fluid level is not at the correct level, add High Performance DOT 3 Brake Fluid C6AZ-19542-AB or DOT 3 equivalent meeting Ford specification ESA-M6C25-A, DOT 3.
NOTE: Prior to performing any diagnosis, make certain that the brake warning indicator is functional.
A change in brake pedal feel is usually the first indicator of a brake system concern. The change may only be normal ABS function, but is sufficient cause for further investigation. The brake warning indicator in the instrument cluster and the brake fluid level in the brake master cylinder reservoir are also indicators of system concerns.
If a wheel is locked and the vehicle must be moved, open a bleeder screw at the locked wheel to let out enough fluid to relieve the pressure. Close the bleeder screw. This bleeding operation may release the brakes but will not correct the cause of trouble. If this does not relieve the locked wheel condition, repair the locked components before proceeding.
BRAKE BOOSTER
Inspect all hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections should be properly secured and in good condition with no holes, soft or collapsed areas.
ROAD TEST
Perform a Road Test to compare actual vehicle braking performance with the performance standards expected by the driver. The ability of the test driver to make valid comparisons and detect performance deficiencies will depend on experience.
The driver should have a thorough knowledge of brake system operation and accepted general performance guidelines in order to make good comparisons and detect performance problems.
Select a road that is reasonably smooth and level. Gravel or bumpy roads, except to demonstrate ABS function, are not suitable. The surface does not allow the tires to grip the road equally. Avoid crowned roads.
A key factor in evaluating brake concerns is the deceleration rate. This varies from vehicle to vehicle and with changes in operating conditions. It is evident how well the brakes are working after just a few applications.
Avoid locking the brakes. Locked brakes are not an indicator of braking efficiency.
Visual Inspection Chart:
For low or spongy brake pedal concerns:
- Check and, if necessary, refill the brake master cylinder reservoir.
- Bleed the brake system and retest the brake pedal feel.
For slow or incomplete brake pedal return concern:
- Inspect for binding, damage, correct installation, or interference at the brake pedal.
- Check the power brake booster for binding, damage, and correct installation.
For a vibration concern when the brakes are applied:
- Road test the vehicle.
- Apply the parking brake and note if vibration is felt.
- If vibration can be felt while applying only the parking brake, machine the brake drums if final internal diameter will be within specification. Retest the vehicle for normal operation.
- If vibration is only felt while applying the brake pedal, use a hub-mount brake lathe to machine the brake discs. Ford recommends on-vehicle rotor machining. Follow the lathe manufacturer's instructions. Retest the vehicle for normal operation.