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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Chevrolet C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Brake System Diagnosis

Brake System Diagnosis Testing

Important: A vehicle that pulls to one side during braking may need a front end alignment. Do not assume that the reason the vehicle pulls to one side is a brake related condition. Ensure that the alignment is correct.

Test the brakes on a dry, clean, reasonably smooth and level roadway. The accuracy of the brake performance cannot be made if the following road conditions exist:

   • Wet roadways
   • Greasy roadways
   • Roadways covered with loose dirt
These road conditions prevent the tires from gripping the road equally. Crowned roadways affect brake testing by throwing the weight of the vehicle toward the wheels on one side of the vehicle. Rough roadways cause the wheels to bounce. Bouncing wheels affect the test accuracy.

Test the brakes at different vehicle speeds with light and heavy pressure. Do not lock the wheels and slide the tires on the roadway. Locked wheels and sliding tires do not indicate brake efficiency. Heavily braked turning wheels will stop the vehicle in less distance then locked wheels. More tire-to-road friction is present with heavily braked turning tires than with sliding tires.

Brake System Diagnosis Causes and Symptoms

Symptom

Causes

Excessive Brake Pedal Travel
    • Leaking brake pipe, hose, or connection. Refer to Brake Pipe Replacement .
    • Leaking piston seal. Refer to Brake Caliper Overhaul .
    • Leaking master cylinder. Refer to Brake Fluid Leak .
    • Air in the brake system. Refer to Hydraulic Brake System Bleeding .
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Uneven lining wear. Replace the linings or correct the condition. Refer to Brake Pad Inspection .
    • Improper thickness variation. Refer to Component Specifications .
    • Excessive lateral run-out. Refer to Brake Rotor Lateral Runout Check .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .

Brake Pedal Travel Gradually Increases
    • Leaking brake pipe, hose, or connection. Refer to Brake Pipe Replacement .
    • Leaking piston seal. Refer to Brake Caliper Overhaul .
    • Leaking master cylinder. Refer to Brake Fluid Leak .
    • Restricted passage in the booster. Refer to Power Brake Booster Replacement .
    • Damaged booster. Refer to Power Brake Booster Replacement .
    • Improper thickness variation. Refer to Component Specifications .
    • Excessive lateral run-out. Refer to Brake Rotor Lateral Runout Check .
    • Restricted brake fluid passage. Refer to Power Brake Booster Replacement .

Excessive Brake Pedal Effort
    • Leaking booster system. Refer to Hydraulic System Fluid Loss .
    • Restricted passage in the booster. Refer to Power Brake Booster Replacement .
    • Damaged booster. Refer to Power Brake Booster Replacement .
    • Worn-out brake lining. Replace the linings. Refer to Disc Brakes.
    • Glazed brake lining. Refer to Disc Brakes.
    • Incorrect brake lining material. Replace the linings. Refer to Disc Brakes.
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Replace the linings. Refer to Disc Brakes.
    • Restricted brake fluid passage. Refer to Power Brake Booster Replacement .
    • Brake pedal linkage Interference or Binding. Refer to Brake Fluid Leak .
    • Operator riding the brake pedal.
    • Rotor or drum surface finish. Refer to Brake Pad and Rotor Burnishing .

Excessive Braking Action
    • Damaged booster. Refer to Power Brake Booster Replacement .
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Incorrect lining material. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Replace the linings. Refer to Disc Brakes.
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .

Brakes Slow To Respond
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Leaking booster system. Refer to Hydraulic System Fluid Loss .
    • Restricted passage in the booster. Refer to Power Brake Booster Replacement .
    • Damaged booster. Refer to Power Brake Booster Replacement .
    • Glazed brake lining. Refer to Disc Brakes.
    • Restricted brake fluid passage. Refer to Brake Fluid Leak .
    • Brake pedal linkage Interference or Binding. Refer to Hydraulic Brake System Bleeding .
    • Sticking caliper or caliper pistons. Refer to Brake Caliper Replacement .

Brakes Slow To Release
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Restricted passage in the booster. Refer to Power Brake Booster Replacement .
    • Damaged booster. Refer to Power Brake Booster Replacement .
    • Restricted brake fluid passage. Refer to Brake Fluid Leak .
    • Brake pedal linkage Interference or Binding. Refer to Brake Fluid Leak .
    • Sticking caliper or caliper pistons. Refer to Brake Caliper Replacement .
    • Parking brake not releasing. Refer to Park Brake.

Brakes Drag
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .
    • Restricted brake fluid passage. Refer to Brake Fluid Leak .
    • Improperly adjusted stoplamp switch.
    • Brake pedal linkage Interference or Binding. Refer to Brake Fluid Leak .
    • Improperly adjusted parking brake. Refer to Park Brake.
    • Loose front suspension attachments. Refer to Front Suspension.
    • Operator riding brake pedal.
    • Sticking caliper or caliper pistons. Refer to Brake Caliper Replacement .

Uneven Braking Action (Side to Side)
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Worn-out brake lining. Replace the linings. Refer to Disc Brakes.
    • Uneven brake wear. Replace or correct.
    • Glazed brake lining. Refer to Disc Brakes.
    • Incorrect brake lining material. Replace the linings. Refer to Disc Brakes.
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Refer to Disc Brakes.
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .
    • Restricted brake fluid passage. Refer to Hydraulic Brake System Bleeding .
    • Improperly adjusted parking brake. Refer to Park Brake.
    • Incorrect front end alignment. Refer to Wheel Alignment.
    • Incorrect tire pressure. Refer to Tires and Wheels.
    • Loose front suspension attachments. Refer to Front Suspension.
    • Sticking caliper or caliper pistons. Refer to Brake Caliper Replacement
    • Parking brake not releasing. Refer to Park Brake.

Uneven Braking Action (Front to Rear)
    • Leaking brake pipe, hose, or connection. Refer to Brake Pipe Replacement .
    • Leaking piston seal. Refer to Brake Caliper Overhaul .
    • Leaking master cylinder. Refer to Brake Fluid Leak .
    • Air in the brake system. Refer to Hydraulic Brake System Bleeding .
    • Contaminated or improper brake fluid. Refer to Master Cylinder Description .
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Glazed brake lining. Refer to Disc Brakes.
    • Incorrect lining material. Replace the linings. Refer to Disc Brakes.
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Replace the linings. Refer to Disc Brakes.
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .
    • Restricted brake fluid passage. Refer to Power Brake Booster Replacement .
    • Improperly adjusted parking brake. Refer to Park Brake.
    • Sticking caliper or caliper pistons. Refer to Brake Caliper Replacement .

Scraping Noise From Brakes
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Replace the linings. Refer to Disc Brakes.
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .
    • Loose front suspension attachments. Refer to Front Suspension.

Brakes Squeak During Application
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Glazed brake lining. Refer to Disc Brakes.
    • Incorrect lining material. Replace the linings. Refer to Disc Brakes.
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Replace the linings. Refer to Disc Brakes.
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .

Brakes Squeak During Stop
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Glazed brake lining. Refer to Disc Brakes.
    • Incorrect lining material. Replace the linings. Refer to Disc Brakes.
    • Contaminated brake lining. Replace the linings. Refer to Disc Brakes.
    • Linings damaged by abuse. Refer to Disc Brakes.
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .

Brakes Chatter (Roughness)
    • Heat spotted or scored discs. Refer to Brake Pad and Rotor Burnishing .
    • Improper thickness variation. Refer to Component Specifications .
    • Excessive lateral run-out. Refer to Brake Rotor Lateral Runout Check .
    • Brake assembly attachments are missing or loose. Refer to Hydraulic Brake System Bleeding .

Brakes Groan At End Of Stop
    • Linings damaged by abuse. Refer to Disc Brakes.
    • Loose front suspension attachments. Refer to Front Suspension.
    • Out-of-balance wheel assemblies. Refer to Tires and Wheels.

Brake Warning Lamp Glows
    • Leaking brake pipe, hose, or connection. Refer to Brake Pipe Replacement .
    • Leaking piston seal. Refer to Brake Caliper Overhaul .
    • Leaking master cylinder. Refer to Brake Fluid Leak .
    • Air in the brake system. Refer to Hydraulic Brake System Bleeding .
    • Contaminated or improper brake fluid. Refer to Brake Fluid and Brake Fluid Handling .
    • Worn-out brake lining. Replace the linings. Refer to Brake Pad Inspection .
    • Uneven lining wear. Replace the lining or correct the condition. Refer to Brake Pad Inspection .
    • Park brake switch circuit grounded. Refer to Park Brake.
    • Parking brake not releasing. Refer to Park Brake.