For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1997 🢒 Chevy P42 Commercial Chassis 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Brake System Diagnosis

Brake System Diagnosis for Chevrolet Chevy P42 Commercial Chassis 1997

Excessive Brake Pedal Travel

Checks

Action

Preliminary Check

Check for air in the hydraulic system. Refer to Bleeding The Brake Hydraulic System.

Additional Checks

•	Check for leaks in brake pipes, in brake hoses, and at connections. Refer to Brake Fluid Leaks.

•	Check for leaks at piston seals. Refer to Seal Leak Diagnosis.

•	Check for leaks at the master cylinder. Refer to Master Cylinder.

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for uneven wear of the brake linings.

•	Check for improper variations in the thickness of the brake linings.

•	Check for excessive lateral runout.

•	Check for missing or loose attachments to the brake assembly.

Brake Pedal Travel Gradually Increases

Checks

Action

Preliminary Checks

•	Check for leaks in brake pipes, in brake hoses, and at connections. Refer to Brake Fluid Leaks.

•	Check for leaks at piston seals. Refer to Seal Leak Diagnosis

•	Check for leaks at the master cylinder. Refer to Master Cylinder.

Additional Checks

•	Check for a restricted passage in the hydraulic booster.

•	Check for damage to the hydraulic booster.

•	Check for improper variation in the thickness of the brake linings.

•	Check for excessive lateral runout.

•	Check for restrictions in the passage of brake fluid.

Excessive Brake Pedal Effort

Checks

Action

Preliminary Checks

•	Check for leaks in the hydraulic booster system. Refer to Hydraulic Booster System Fluid Loss.

•	Check for glazed brake linings.

Additional Checks

•	Check for a restricted passage in the hydraulic booster.

•	Check for damage to the hydraulic booster.

•	Check for worn-out brake linings.

•	Check for brake linings of an incorrect material.

•	Check for contaminated brake linings.

•	Check for brake linings that have been damaged by abuse.

•	Check for restricted passages of brake fluid.

•	Check for interference or binding in the brake pedal linkage. Refer to Brake Pedal Linkage.

•	Check to see if the driver rides the brake pedal.

•	Check the finish on the rotor surface.

Excessive Braking Action

Checks

Action

Preliminary Check

Check for brake linings that have been damaged by abuse.

Additional Checks

•	Check for damage to the hydraulic booster.

•	Check for worn-out brake linings.

•	Check for brake linings that have uneven wear.

•	Check for brake lining of an incorrect material.

•	Check for brake discs that are heat-spotted or scored.

•	Check for missing or loose attachments to the brake assembly.

Brakes Are Slow To Respond

Checks

Action

Preliminary Check

Check for a restricted passage in the hydraulic booster.

Additional Checks

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for leaks in the hydraulic booster system. Refer to Hydraulic Booster System Fluid Loss.

•	Check for brake linings that are glazed.

•	Check for restricted passage of brake fluid.

•	Check for interference or binding in the brake pedal linkage.

•	Check for binding in the caliper or caliper pistons.

Brakes Are Slow To Release

Checks

Action

Preliminary Checks

•	Check for damage to the hydraulic booster.

•	Check for interference or binding in the brake pedal linkage.

Additional Checks

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for a restricted passage in the hydraulic booster.

•	Check for a restricted passage of brake fluid.

•	Check for binding calipers or caliper pistons

•	Check for a stuck parking brake.

Brakes Drag

Checks

Action

Preliminary Checks

•	Check for interference or binding in the brake pedal linkage. Refer to Brake Pedal Linkage.

•	Check for binding calipers or caliper pistons.

Additional Checks

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for missing or loose attachments to the brake assembly.

•	Check for a restricted passage of brake fluid.

•	Check for an improperly adjusted stoplamp switch. Refer to Stoplamp Switch Adjustment.

•	Check for an improperly adjusted parking brake.

•	Check for loose attachments to the front suspension.

•	Check to see if the driver rides the brake pedal.

Uneven Braking Action (Side to Side)

Checks

Action

Preliminary Checks

•	Check for contaminated brake linings.

•	Check for incorrect front end alignment

Additional Checks

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for worn-out brake linings.

•	Check for uneven wear of the brake linings.

•	Check for brake linings that are glazed.

•	Check for brake linings of an incorrect material.

•	Check for brake linings that have been damaged by abuse.

•	Check for brake discs that are heat-spotted or scored. Check for missing or loose attachments to the brake assembly

•	Check for a restricted passage of brake fluid

•	Check for an improperly adjusted parking brake.

•	Check for incorrect tire pressure.

•	Check for loose attachments to the front suspension. Check for binding calipers or caliper pistons.

•	Check for a stuck parking brake.

Uneven Braking Action (Front to Rear)

Checks

Action

Preliminary Check

Check for contaminated brake linings.

Additional Checks

•	Check for leaks in brake pipes, in brake hoses, or at connections. Refer to Brake Fluid Leaks.

•	Check for leaks at piston seals. Refer to Seal Leak Diagnosis

•	Check for leaks at the master cylinder. Refer to Master Cylinder.

•	Check for air in the hydraulic system. Refer to Bleeding the Brake Hydraulic System.

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for worn-out brake linings.

•	Check for uneven wear of the brake linings.

•	Check for brake linings that are glazed.

•	Check for brake linings of an incorrect material.

•	Check for brake linings that have been damaged by abuse.

•	Check for brake discs that are heat-spotted or scored.

•	Check for missing or loose attachments to the brake assembly.

•	Check for a restricted passage of brake fluid.

•	Check for an improperly adjusted parking brake.

•	Check for binding calipers or caliper pistons.

Scraping Noise From Brakes

Checks

Action

Preliminary Check

Check for loose attachments to the front suspension.

Additional Checks

•	Check for worn-out brake linings.

•	Check for brake linings that have uneven wear.

•	Check for contaminated brake linings.

•	Check for brake linings that have been damaged by abuse.

•	Check for missing or loose attachments to the brake assembly.

Brakes Squeak During Application

Checks

Action

Preliminary Checks

•	Check for worn-out brake linings.

•	Check for brake linings that have uneven wear.

•	Check for brake linings that are glazed.

•	Check for brake linings of an incorrect material.

•	Check for contaminated brake linings.

•	Check for brake linings that have been damaged by abuse.

•	Check for brake discs that are heat-spotted or scored.

Brakes Squeak During Stop

Checks

Action

Preliminary Check

Check for brake linings that have uneven wear.

Additional Checks

•	Check for worn-out brake linings.

•	Check for brake linings that are glazed.

•	Check for brake linings of an incorrect material.

•	Check for contaminated brake linings.

•	Check for brake linings that have been damaged by abuse.

•	Check for brake discs that are heat-spotted or scored.

•	Check for missing or loose attachments to the brake assembly.

Brakes Chatter (Roughness)

Checks

Action

Preliminary Checks

•	Check for brake discs that are heat-spotted or scored.

•	Check for improper variation in the thickness of the brake lining.

Additional Checks

•	Check for excessive lateral runout

•	Check for missing or loose attachments to the brake assembly.

Brakes Groan at the End of a Stop

Checks

Action

Preliminary Check

Check for wheel assemblies that are out of balance.

Additional Checks

•	Check for brake linings that have been damaged by abuse.

•	Check for loose attachments to the front suspension.

"BRAKE" Warning Lamp Stays Lit

Checks

Action

Preliminary Checks

•	Check for leaks in the brake pipes, in the brake hoses, or at connections. Refer to Brake Fluid Leaks.

•	Check for air in the hydraulic system. Refer to Bleeding the Brake Hydraulic System.

•	Check for a short to ground in the parking brake switch circuit.

•	Check for a stuck parking brake.

Additional Checks

•	Check for leaks at the piston seal. Refer to Seal Leak Diagnosis.

•	Check for leaks at the master cylinder. Refer to Master Cylinder.

•	Check for contaminated or improper brake fluid. Refer to Substandard or Contaminated Brake Fluid.

•	Check for worn-out brake linings.

•	Check for brake linings that have uneven wear.