Disc Brake System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2003 GMC Savana Special, 2003 GMC Savana Camper Special, 2003 GMC Savana, 2003 Chevrolet RV Cutaway, and 2003 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

Were you sent here from DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKE? If so, go to next step. If not, see DIAGNOSTIC STARTING POINT - HYDRAULIC BRAKE under TROUBLE SHOOTING.
Visually inspect the disc brake pads for the following:
- Lining thickness.
- Uneven and/or abnormal wear (edge-to-edge and/or side-to-side).
- Evidence of contamination from an external substance.
- Looseness or damage (including pad hardware).
Did you find any conditions to indicate a concern with any of the (front and/or rear) disc brake pads? If so, go to next step. If not, go to step 12 .
Are any of the (front and/or rear) disc brake pads contaminated? If so, go to step 8 . If not, go to next step.
Are any of the (front and/or rear) disc brake pads worn unevenly? If so, go to step 7 . If not, go to next step.
Are any of the (front and/or rear) disc brake pads and/or pad hardware loose or damaged? If so, go to step 7 . If not, go to next step.
Remove and inspect the worn disc brake pads for glazing, looseness, heat spots or damage. Replace the worn disc brake pads as a complete axle set. See BRAKE PADS under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .

NOTE: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from it's mount and the hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper, which may cause damage to the brake hose and in turn may cause a brake fluid leak.

Remove the (front and/or rear) disc brake calipers (as appropriate) from the mounting brackets and support the calipers. DO NOT disconnect the hydraulic brake flex hoses from the calipers. See BRAKE CALIPERS under REMOVAL & INSTALLATION. Inspect the disc brake caliper mounting bracket and the mounting/sliding hardware for the following conditions:
- Loose, bent, cracked, or damaged caliper mounting bracket.
- Binding or seized hardware.
- Worn, damaged or missing hardware components.
Replace components as required. Refer to the following procedures as required:
- BRAKE CALIPER BRACKETS under REMOVAL & INSTALLATION.
- DISC BRAKE HARDWARE under REMOVAL & INSTALLATION.
Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. See BRAKE PADS under REMOVAL & INSTALLATION. After repairs are complete, go to step 12 .
Inspect the disc brake calipers, brake hoses and brake pipes for evidence of an external brake fluid leak. Replace any components found to be leaking brake fluid. Refer to the following procedures as required:
- FRONT BRAKE CALIPER or REAR BRAKE CALIPER under OVERHAUL.
- BRAKE CALIPER under REMOVAL & INSTALLATION.
- BRAKE HOSES under REMOVAL & INSTALLATION.
- BRAKE PIPE under REMOVAL & INSTALLATION.
Did you find and correct the source of the leak causing contamination of the pads? If so, go to step 11 . If not, go to next step.
Inspect the wheel drive shaft outer seals (boots), if equipped, for damage and evidence of a grease leak. Replace any wheel drive shaft seal (boot) that is found to be leaking grease which may be the source of the contamination to the pads. See appropriate AXLE SHAFTS article in DRIVELINE/AXLES. Inspect the rear axle seals for damage and evidence of a lubricant leak. Replace any rear axle seal that is found to be leaking lubricant which may be the source of the contamination to the pads. See REAR OIL SEAL AND/OR BEARING REPLACEMENT in appropriate AXLE SHAFTS article in DRIVELINE/AXLES. Did you find and correct the source of the leak causing contamination of the pads? If so, go to step 11 . If not, go to next step.
Inspect the following systems for damage and evidence of an external fluid leak. Replace any components found to be leaking fluid which may be the source of the contamination to the pads. Refer to the following articles:
- POWER STEERING in STEERING.
- ENGINE MECHANICAL in ENGINES.
- AUTOMATIC TRANSMISSION in TRANSAXLES/TRANSMISSIONS.
Did you find and correct the source of the leak causing contamination of the pads? If so, go to next step.
Clean the remaining disc brake system components to remove any traces of the contaminant. Remove the (front and/or rear) disc brake calipers (as appropriate) from the mounting brackets and support the calipers. DO NOT disconnect the hydraulic brake flex hoses from the calipers. See BRAKE CALIPERS under REMOVAL & INSTALLATION. Inspect the disc brake caliper mounting/sliding hardware for the following conditions:
- Binding or seized hardware.
- Distorted, worn, damaged or missing hardware components.
Replace the caliper mounting/sliding hardware components as required. See DISC BRAKE HARDWARE under REMOVAL & INSTALLATION. Replace the contaminated disc brake pads as a complete axle set. See BRAKE PADS and/or under REMOVAL & INSTALLATION. Did you complete the cleaning, inspection and replacement? If so, go to next step.
Visually inspect each of the disc brake rotor shields/backing plates for evidence of contact with the brake rotors. Are any of the brake rotor shields/backing plates contacting the brake rotors? If so, go to next step. If not, go to step 14 .
Repair or replace the disc brake rotor shields/backing plates as required. See FRONT DISC BRAKE SPLASH SHIELD and/or REAR DISC BRAKE BACKING PLATE under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
Check the thickness of each of the disc brake rotors. Make a determination for each brake rotor if the rotor can be refinished and remain above the minimum requirements. See BRAKE ROTOR THICKNESS under ADJUSTMENTS & INSPECTIONS. Does the disc brake rotor meet the minimum requirements for refinishing? If so, go to next step. If not, go to step 17 .
Inspect each of the disc brake rotors for the following surface and wear conditions:
Braking Surface Conditions
- Heavy rust and/or pitting.
- Cracks and/or heat spots.
- Excessive blueing discoloration.
Braking Surface Wear Conditions
- Deep or excessive scoring beyond maximum acceptable level.
- Lateral runout beyond maximum acceptable level.
- Thickness variation beyond maximum acceptable level.
Make a determination for each brake rotor if the rotor requires refinishing based upon the results of the inspection. If the brake rotor exhibits any of the following conditions, it requires refinishing.
- Rotor exhibits one or more of the Braking Surface Conditions listed previously.
- Rotor is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously.
Does the brake rotor require refinishing? If so, go to next step. If not, go to step 20 .
Refinish the brake rotor. See BRAKE ROTOR REFINISHING under ADJUSTMENTS & INSPECTIONS. Inspect the brake rotor thickness. See BRAKE ROTOR THICKNESS in DISC BRAKE SYSTEM under ADJUSTMENTS & INSPECTIONS. Were you able to refinish the brake rotor within the minimum requirements? If so, go to step 20 . If not, go to step 19 .
Is the brake rotor at or below the discard requirements? If so, go to step 19 . If not, go to next step.
Inspect each of the disc brake rotors for the following surface and wear conditions:
Braking Surface Conditions
- Heavy rust and/or pitting.
- Cracks and/or heat spots.
- Excessive blueing discoloration.
Braking Surface Wear Conditions
- Deep or excessive scoring beyond maximum acceptable level.
- Lateral runout beyond maximum acceptable level.
- Thickness variation beyond maximum acceptable level.
Make a determination for each brake rotor if the rotor requires replacement based upon the results of the inspection. If a brake rotor exhibits any of the previously listed conditions, it requires replacement.
- Rotor exhibits one or more of the Braking Surface Conditions listed previously.
- Rotor is beyond the acceptable level in one or more of the Braking Surface Wear Conditions listed previously.
Does the brake rotor require replacement? If so, go to next step. If not, go to step 20 .
Replace the brake rotor. See BRAKE ROTORS under REMOVAL & INSTALLATION. After repairs are complete, go to next step.
Install or connect components that were removed or disconnected during diagnosis. Did you complete the operation? If so, then system is okay. If system is not okay, go to step 2 .