Inspection and Verification
Special Tools:
Special Tool(s)
Inspection and Verification
WARNING: Use of any other than the approved DOT 3 or DOT 4 brake fluid will cause permanent Manage to brake components and will render the brakes inoperative.
WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with eyed Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes with water for IS 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, dean the brake reservoir filler cap before removing, and add DOT 3 brake fluid. If DOT 3 is not available use DOT 4 brake fluid.
NOTE: Prior to carrying out any diagnosis, make sure the brake warning indicator is functional.
The first indication that something may be wrong in the brake system is a change in the feeling through the brake pedal. 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.
Inspect all hoses and connections. All unused vacuum connectors should be capped. Make sure hoses and their connections are correctly secured and in good condition with no holes, soft or collapsed areas.
Non-Pressure Leaks
The only part of the brake system that could have a brake fluid loss that does not appear when the system is under pressure is the brake master cylinder reservoir area. Brake fluid loss can be caused by a missing or poorly-fitted brake master cylinder filler cap, a punctured or otherwise damaged brake master cylinder reservoir, a missing or damaged brake master cylinder filler cap gasket, or by missing, damaged or poorly-fitted sealing grommets between the brake master cylinder and the brake master cylinder reservoir.
The brake master cylinder reservoir grommets are not separately serviceable and must be installed new as part of a new brake master cylinder reservoir.
Install a new flexible brake hose if it shows signs of softening, cracking or other damage.
When installing a new brake hose, position the hose to avoid contact with other vehicle components.
Road Test
If a road test is performed, select a road that is reasonably smooth and level. Gravel or bumpy roads are not suitable because 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 indication 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.
^ if the brake pedal is still low or feels spongy, check the brake pedal mounting for looseness and correct installation. Check the power brake booster and the brake master cylinder for loose mounting. Correct as necessary and retest the system for normal operation.
For a 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 excessive or erratic brake pedal travel concerns:
^ Check for spongy pedal and bleed as necessary.
^ Check the brake pedal mounting for wear, damage, binding and correct installation.
^ Check the disc brake caliper components for wear, damage, binding and correct installation.
^ Check the power brake booster, and brake master cylinder for damage and correct installation.
^ Check wheel bearings and rear axle end play. Correct as necessary.
Vibration When Brakes Are Applied
For vibration concerns when brakes are applied, perform the following procedure.
Visually inspect:
^ Tire condition and pressure.
^ Suspension bushings and ball joints.
Correct as necessary.
1. Verify and isolate the concern. Brake roughness can be felt in:
^ the steering wheel
^ the seat
^ the brake pedal
2. After verifying the concern, check for related concerns in the:
^ Technical Service Bulletins
3. Check wheel bearing end-play and correct as necessary.
4. NOTE: Begin at the front of the vehicle unless the vibration has been isolated to the rear.
Remove the tire and wheel.
5. Remove the brake caliper.
6. Measure and record the brake disc thickness. Install a new brake disc if the brake disc thickness is less than 0.60 mm (0.024 inch) above the minimum thickness specification. This will make sure that the brake disc thickness will be above minimum thickness after it has been machined.
7. For vehicles with a two-piece hub and brake disc assembly:
^ Match-mark before disassembly.
^ Remove the brake disc.
^ Using a die grinder with a mild abrasive (Scotch Brite type), remove any rust or corrosion from the hub and brake disc mounting surfaces.
^ Align the match-marks and reinstall the brake disc on the hub.
5. CAUTION: Do not use a bench lathe to machine brake discs.
NOTE: The depth of cut must be between 0.10 and 0.20 mm (0.004 and 0.008 inch). Lighter cuts will cause heat and wear. Heavier cuts will cause poor brake disc surface finish.
Using the special tool, machine the brake discs. Follow the manufacturer's instructions. After machining, make sure the brake disc still meets the thickness specification.
9. Using a dial indicator, verify that the brake disc lateral runout is now within specification.
10. Remove the special tool hub adapter.
11. Remove any remaining metal chips from the machining operation.
12. For vehicles with a two-piece hub and brake disc assembly:
^ Remove the brake disc from the hub.
^ Remove any remaining metal chips from hub and brake disc mounting surfaces and from the ABS sensor.
^ Apply anti-seize lubricant to the mounting surfaces.
^ Using the match marks, mount the brake disc on the hub.
13. Install the caliper and check brake operation.