GM Service Manual Online
For 1990-2009 cars only

Symptom

Cause

Excessive brake pedal travel

    â€¢ Air in brake system
    â€¢ Leaking brake line or connection
    â€¢ Leaking piston seal
    â€¢ Leaking master cylinder
    â€¢ Uneven brake lining wear
    â€¢ Incorrect lining material
    â€¢ Excessive lateral runout
    â€¢ Faulty automatic adjuster
    â€¢ Missing or loose brake assembly attachments
    â€¢ Incorrect wheel bearing runout
    â€¢ Operator riding brake pedal
    â€¢ Improper booster pushrod length
    â€¢ Caliper not sliding freely

Brake pedal travel gradually increases

    â€¢ Leaking brake line or connection
    â€¢ Leaking piston seal
    â€¢ Leaking master cylinder
    â€¢ Restricted brake fluid passage or sticking wheel cylinder piston
    â€¢ Incorrect stoplamp switch adjustment
    â€¢ Operator riding brake pedal

Excessive brake pedal effort

    â€¢ Surface finish in rotors
    â€¢ Leaking vacuum system
    â€¢ Restricted air passage in power head
    â€¢ Damaged brake booster
    â€¢ Improperly assembled brake booster valving
    â€¢ Worn out brake lining
    â€¢ Incorrect lining material
    â€¢ Linings damaged by abusive use
    â€¢ Restricted brake fluid passage
    â€¢ Brake pedal linkage interference or binding
    â€¢ Operator riding brake pedal
    â€¢ Sticking caliper pistons
    â€¢ Faulty proportioning valve

Excessive braking action

    â€¢ Contaminated brake lining
    â€¢ Linings damaged by abusive use
    â€¢ Leaking piston seal
    â€¢ Damaged brake booster
    â€¢ Improperly assembled brake booster valving
    â€¢ Incorrect lining material
    â€¢ Heat spotted or scored brake rotors
    â€¢ Incorrect stoplamp switch adjustment
    â€¢ Operator riding brake pedal
    â€¢ Improper booster pushrod length
    â€¢ Caliper not sliding freely
    â€¢ Faulty proportioning valve

Brakes slow to respond

    â€¢ Restricted air passage in power head
    â€¢ Contaminated or improper brake fluid
    â€¢ Leaking vacuum system
    â€¢ Improperly assembled brake booster valving
    â€¢ Brake pedal linkage interference or binding
    â€¢ Brake linkage interface or binding
    â€¢ Faulty proportioning valve
    â€¢ Damaged brake booster

Brakes slow to release

    â€¢ Brake pedal linkage interference or binding
    â€¢ Contaminated or improper brake fluid
    â€¢ Restricted air passage in power head
    â€¢ Damaged brake booster
    â€¢ Improperly assembled brake booster valving
    â€¢ Insufficient brake pad guide lubricant
    â€¢ Restricted brake fluid passage
    â€¢ Parking cable seized
    â€¢ Improper booster pushrod length
    â€¢ Sticking caliper pistons
    â€¢ Faulty proportioning valve

Brakes drag

    â€¢ Improperly assembled brake booster valving
    â€¢ Incorrect stoplamp switch adjustment
    â€¢ Brake pedal linkage interference or binding
    â€¢ Improper booster pushrod length
    â€¢ Faulty proportioning valve
    â€¢ Caliper not sliding freely
    â€¢ Sticking caliper pistons
    â€¢ Operator riding brake pedal
    â€¢ Parking brake cable seized
    â€¢ Improperly adjusted parking brake
    â€¢ Restricted brake fluid passage
    â€¢ Missing or loose brake assembly attachments
    â€¢ Faulty automatic adjusters
    â€¢ Damaged brake booster
    â€¢ Contaminated or improper brake fluid

Uneven braking action (side to side)

    â€¢ Contaminated brake lining
    â€¢ Incorrect front end alignment
    â€¢ Leaking brake line or connection
    â€¢ Leaking piston seal
    â€¢ Air to brake system
    â€¢ Worn out brake lining
    â€¢ Uneven brake lining wear
    â€¢ Incorrect lining material
    â€¢ Linings damaged by abusive use
    â€¢ Heat spotted or scored rotors
    â€¢ Faulty automatic adjusters
    â€¢ Missing or loose brake assembly attachments
    â€¢ Insufficient brake pad guide lubricant
    â€¢ Restricted brake fluid passage
    â€¢ Loose front suspension attachments
    â€¢ Sticking caliper pistons
    â€¢ Faulty proportioning valve
    â€¢ Incorrect stoplamp switch adjustment

Uneven braking action (front to back)

    â€¢ Worn out brake lining
    â€¢ Uneven brake lining wear
    â€¢ Incorrect lining material
    â€¢ Contaminated brake lining
    â€¢ Linings damaged by abusive use
    â€¢ Heat spotted rotors
    â€¢ Faulty automatic adjusters
    â€¢ Missing or loose brake assembly attachment
    â€¢ Restricted brake fluid passage
    â€¢ Parking brake cable seized
    â€¢ Operator riding brake pedal
    â€¢ Sticking caliper pistons

Scraping noise from brakes

    â€¢ Loose front suspension attachments
    â€¢ Caliper not sliding freely
    â€¢ Incorrect wheel bearing runout
    â€¢ Loose or missing brake assembly attachments
    â€¢ Linings damaged by abusive use
    â€¢ Contaminated brake lining
    â€¢ Uneven brake lining wear
    â€¢ Worn out brake lining

Brakes squeak during application

    â€¢ Excessive lateral runout
    â€¢ Heat spotted or scored brake drum or rotors
    â€¢ Linings damaged by abusive use
    â€¢ Contaminated brake lining
    â€¢ Uneven brake lining wear
    â€¢ Operator riding brake pedal
    â€¢ Loose or missing brake assembly attachments
    â€¢ Linings damaged by abusive use
    â€¢ Incorrect lining material
 

Brakes pulsate (roughness)

    â€¢ Caliper not sliding freel
    â€¢ Improper rotor thickness variation
    â€¢ Incorrect lining material
    â€¢ Heat spotted rotors
    â€¢ Out-of-round brake rotors or drums
    â€¢ Excessive lateral runout
    â€¢ Missing or loose brake assembly attachments

Brakes groan at end of stop

    â€¢ Worn out brake lining
    â€¢ Uneven brake lining wear
    â€¢ Incorrect lining material
    â€¢ Contaminated brake lining
    â€¢ Linings damaged by abusive use
    â€¢ Heat spotted rotors
    â€¢ Missing or loose brake assembly attachments
    â€¢ Loose front suspension attachments
    â€¢ Operator riding brake pedal

BRAKE warning lamp glows

    â€¢ Leaking brake line or connection
    â€¢ Leaking piston seal
    â€¢ Leaking master cylinder
    â€¢ Contaminated or improper brake fluid
    â€¢ Improperly adjusted parking brake
    â€¢ Parking brake cable seized
    â€¢ Short to ground CKT 1134