DEFINITION: This diagnostic table is designed to diagnose ONLY the components of the DISC brake system in order to determine if the DISC brake system is operating properly. You will be directed by the appropriate Symptom table to go to other brake system diagnostic tables as appropriate.

Were you sent here from a Brake Symptom table?

Go to Step 2

Go to Diagnostic Starting Point - Hydraulic Brakes

Visually inspect the disc brake pads for the following conditions:

Refer to Brake Pad Inspection.

Did you find any conditions to indicate a concern with any of the front and/or rear disc brake pads?

Go to Step 3

Go to Step 12

Are any of the front and/or rear disc brake pads contaminated?

Go to Step 8

Go to Step 4

Are any of the front and/or rear disc brake pads worn unevenly?

Go to Step 7

Go to Step 5

Are any of the front and/or rear disc brake pads and/or pad hardware loose or damaged?

Go to Step 7

Go to Step 6

1. Remove and inspect the worn disc brake pads for glazing, looseness, heat spots or damage.
2. Replace the worn disc brake pads as a complete axle set. Refer to Front Disc Brake Pads Replacement and/or Rear Disc Brake Pads Replacement.

Did you complete the inspection and replacement?

Go to Step 12

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Caution: Support the brake caliper with heavy mechanic wire, or equivalent, whenever it is separated from its 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.

Note: Do NOT disconnect the hydraulic brake flex hoses from the calipers.

1. Remove the front and/or rear disc brake calipers, as appropriate, from the mounting brackets and support the calipers. Refer to Front Brake Caliper Replacement and/or Rear Brake Caliper Replacement.
2. Inspect the disc brake caliper mounting bracket and the mounting/sliding hardware for the following conditions:

Refer to Front Disc Brake Mounting and Hardware Inspection and/or Rear Disc Brake Mounting and Hardware Inspection.

•	Binding or seized hardware

•	Worn, damaged or missing hardware components

•	Loose, bent, cracked, or damaged caliper mounting bracket

3. Replace components as required. Refer to the following procedures, as required:

•	Front Brake Caliper Bracket Replacement

•	Rear Brake Caliper Bracket Replacement

•	Front Disc Brake Hardware Replacement

•	Rear Disc Brake Hardware Replacement

4. Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. Refer to Front Disc Brake Pads Replacement and/or Rear Disc Brake Pads Replacement.

Did you complete the inspection and replacement?

Go to Step 12

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1. Inspect the disc brake calipers, brake hoses and brake pipes for evidence of an external brake fluid leak.
2. Replace any components found to be leaking brake fluid. Refer to the following procedures as required:

•	Front Brake Caliper Overhaul or Front Brake Caliper Replacement

•	Rear Brake Caliper Overhaul or Rear Brake Caliper Replacement

•	Front Brake Hose Replacement

•	Rear Brake Hose Replacement

•	Brake Pipe Replacement

Did you find and correct the source of the leak causing contamination of the pads?

Go to Step 11

Go to Step 9

9

1. Inspect the wheel drive shaft outer seals for damage and evidence of a grease leak.
2. Replace any wheel drive shaft seal that is found to be leaking grease which may be the source of the contamination to the pads. Refer to Wheel Drive Shaft Outer Joint and Boot Replacement.

Did you find and correct the source of the leak causing contamination of the pads?

Go to Step 11

Go to Step 10

10

1. Inspect the automatic transmission cooling system lines, if equipped, for damage and evidence of an external fluid leak which may be the source of the contamination to the pads.
2. Inspect the power steering system hoses for damage and evidence of an external fluid leak which may be the source of the contamination to the pads.
3. Replace any components found to be leaking fluid which may be the source of the contamination to the pads.

Did you find and correct the source of the leak causing contamination of the pads?

Go to Step 11

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1. Clean the remaining disc brake system components to remove any traces of the contaminant.

Caution: Support the brake caliper with heavy mechanic wire, or equivalent, whenever it is separated from its 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.

Note: Do NOT disconnect the hydraulic brake flex hoses from the calipers.

2. Remove the front and/or rear disc brake calipers, as appropriate, from the mounting brackets and support the calipers. Refer to Front Brake Caliper Replacement and/or Rear Brake Caliper Replacement.
3. Inspect the disc brake caliper mounting/sliding hardware for the following conditions:

Refer to Front Disc Brake Mounting and Hardware Inspection and/or Rear Disc Brake Mounting and Hardware Inspection.

•	Binding or seized hardware

•	Distorted, worn, damaged or missing hardware components

4. Replace the caliper mounting/sliding hardware components as required. Refer to Front Disc Brake Hardware Replacement and/or Rear Disc Brake Hardware Replacement.
5. Replace the contaminated disc brake pads as a complete axle set. Refer to Front Disc Brake Pads Replacement and/or Rear Disc Brake Pads Replacement.

Did you complete the cleaning, inspection and replacement?

Go to Step 12

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12

Visually inspect each of the rear disc brake rotor shields/backing plates, if equipped, for evidence of contact with the brake rotors.

Are any of the brake rotor shields/backing plates contacting the brake rotors?

Go to Step 13

Go to Step 14

Repair or replace the disc brake rotor shields/backing plates as required. Refer to Rear Disc Brake Backing Plate Replacement.

Did you complete the repair or replacement?

Go to Step 14

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1. Check the thickness of each of the disc brake rotors.

Note: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH rotor.

2. Make a determination for each brake rotor if the rotor can be REFINISHED and REMAIN ABOVE the minimum requirements.

Refer to Brake Rotor Thickness Measurement.

Does the disc brake rotor meet the minimum requirements for REFINISHING?

Go to Step 15

Go to Step 18

15

Note: Perform the following inspection AND ANSWER the question INDIVIDUALLY for EACH rotor.

Inspect each of the disc brake rotors for thickness variation that exceeds the maximum acceptable level. Refer to Brake Rotor Thickness Variation Measurement.

Does the brake rotor exhibit thickness variation that exceeds the maximum acceptable level?

Go to Step 17

Go to Step 16

1. Inspect each of the disc brake rotors for the following surface and wear conditions:

Refer to Brake Rotor Surface and Wear Inspection.

•	Heavy rust and/or pitting

•	Cracks and/or heat spots

•	Excessive blueing discoloration

•	Deep or excessive scoring beyond maximum acceptable level

Note: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH rotor.

2. 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 conditions listed previously, it requires refinishing.

Does the brake rotor require REFINISHING?

Go to Step 17

Go to Step 22

1. Refinish the brake rotor. Refer to Brake Rotor Refinishing.
2. Inspect the brake rotor thickness. Refer to Brake Rotor Thickness Measurement.

Were you able to REFINISH the brake rotor within the minimum requirements?

Go to Step 22

Go to Step 21

Is the brake rotor at or below the DISCARD requirements (J55), or below the MINIMUM THICKNESS requirements, (JL9)?

Go to Step 21

Go to Step 19

19

Note: Perform the following inspection AND ANSWER the question INDIVIDUALLY for EACH rotor.

Inspect each of the disc brake rotors for thickness variation that exceeds the maximum acceptable level. Refer to Brake Rotor Thickness Variation Measurement.

Does the brake rotor exhibit thickness variation that exceeds the maximum acceptable level?

Go to Step 21

Go to Step 20

1. Inspect each of the disc brake rotors for the following surface and wear conditions:

Refer to Brake Rotor Surface and Wear Inspection.

•	Heavy rust and/or pitting

•	Cracks and/or heat spots

•	Excessive blueing discoloration

•	Deep or excessive scoring beyond maximum acceptable level

Note: Make the following determination AND ANSWER the question INDIVIDUALLY for EACH rotor.

2. Make a determination for each brake rotor if the rotor requires replacement based upon the results of the inspection.

If the brake rotor exhibits any of the conditions listed previously, it requires replacement.

Does the brake rotor require REPLACEMENT?

Go to Step 21

Go to Step 22

Note: Whenever a brake rotor is replaced, the assembled lateral runout (LRO) of the rotor must be measured to ensure optimum performance of the disc brakes.

Replace the brake rotor. Refer to Front Brake Rotor Replacement or Rear Brake Rotor Replacement.

Did you complete the replacement?

Go to Step 24

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22

Note: Perform the following inspection AND ANSWER the question INDIVIDUALLY for EACH rotor.

Inspect each of the disc brake rotors for assembled lateral runout (LRO) that exceeds the maximum acceptable level. Refer to Brake Rotor Assembled Lateral Runout Measurement.

Does the brake rotor exhibit assembled LRO that exceeds the maximum acceptable level?

Go to Step 23

Go to Step 24

Correct the LRO for each brake rotor that was determined to have LRO exceeding the maximum acceptable level. Refer to Brake Rotor Assembled Lateral Runout Correction.

Did you complete the operation?

Go to Step 24

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Install or connect components that were removed or disconnected during diagnosis.

Did you complete the operation?

Disc Brake System OK

Return to Symptom Table

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