Diagnosis Of Brake System - GMC G Service Manual

DIAGNOSIS OF BRAKE SYSTEM

PROBLEM
1. Incorrect tire pressure.
Uneven Brake Action
2. Front end out of alignment.
(Brakes Pull)
3. Loose suspension parts.
4. Worn out brake lining.
5. Incorrect lining material.
6. Malfunctioning caliper assembly.
7. Loose calipers.
8. Contaminated brake linings.
9. Malfunctioning rear brakes.
10. Leaking wheel or piston cylinder seal.
11. Restricted brake tubes or hoses.
12. Unmatched tires on the same axle.
1. Worn out linings.
Brakes Squeak
2. Glazed brake lining.
3. Heat spotted rotors or drums.
4. Weak or incorrect brake shoe retention
5. Contaminated brake linings.
6. Incorrect lining material.
7. Brake assembly attachments missing or
8. Excessive brake lining dust.
1. Excessive rotor lateral runout.
Brake Pedal Pulsates
2. Rear drums out of round.
3. Heat spotted rotors or drums.
4. Incorrect wheel bearing adjustments.
5. Out of balance wheel assembly attachments
6. Brake assembly attachments missing or
1. Leaking vacuum system.
Excessive Pedal
2. Malfunctioning power brake unit.
Effort
3. Worn out linings.
4. Malfunctioning proportioning valve.
5. Incorrect lining material.
6. Incorrect wheel cylinder.
1. Insufficient fluid in master cylinder reservoir.
Excessive Pedal
Travel
2. Air in brake system.
3. Malfunctioning self adjusters.
4. Master cylinder.
5. Incorrect wheel bearing adjustment.
6. Improperly adjusted master cylinder
POSSIBLE CAUSE
springs.
loose.
missing or loose.
loose.
push rod.
HYDRAULIC BRAKES 5A-3
CORRECTION
1. Inflate evenly on both sides to specifications.
2. Check and align to specifications.
3. Check all suspension mountings.
4. Replace with lining of correct material.
5. Replace with linings of correct material.
6. Check for frozen or sluggish pistons and the
lubrication of the retainer bolts. Caliper
should slide.
7. Check and torque.
8. Repair as necessary. Replace linings in com­
plete axle sets.
9. Check for inoperative self adjusters. Weak
return springs. Leaking wheel cylinders.
10. Repair as necessary.
11. Check for collapsed rubber hoses or
damaged lines. Repair as necessary.
12. Same style tires with about the same tread
should be used on the same axle.
1. Replace linings.
2. Replace linings.
3. Check per instructions. If within specifica­
tions machine the rotor or drum.
4. Replace with new retention springs.
5. Repair as necessary. Replace linings in com­
plete axle sets.
6. Replace with linings of correct material.
7. Repair as necessary.
8. Clean dust from brake assembly.
1. Check per instructions. If within specifica­
tions machine the rotor.
2. Check per instructions. If within specifica­
tions machine the drum.
3. Check per instructions. If within specifica­
tions machine the rotor or drum.
4. Repair as necessary.
5. Repair as necessary.
6. Repair as necessary.
1. Repair as necessary.
2. Repair as necessary.
3. Replace linings.
4. Repair as necessary.
5. Replace with linings of correct materials.
6. Replace with correct size wheel cylinder.
1. Fill reservoir with approved brake fluid.
Check for leaks and air in the system. Check
indicator light.
2. Check for leaks in lines, wheel cylinders, or
master cylinder. Bleed the system.
3. Repair as necessary.
4. Replace or repair as necessary.
5. Repair as necessary.
6. Adjust master cylinder pushrod.
GMTB-0522-2L