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Disc Brake System Diagnosis

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.

  2. Lubricant leaks from non-brake system components may come in contact with and contaminate brake system components.

  3. Disc brake rotor shields/backing plates that come in contact with disc brake rotors may cause brake system noise.

  1. Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.

  1. Disc brake rotor thickness variation that exceeds the maximum acceptable level can cause brake pulsation.

  1. Disc brake rotor assembled lateral runout (LRO) that exceeds the maximum acceptable level can lead to thickness variation.

Step

Action

Yes

No

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 correctly. You will be directed by the appropriate Symptom table to go to other brake system diagnostic tables as appropriate.

1

Were you sent here from a Brake Symptom table?

Go to Step 2

Go to Symptoms - Hydraulic Brakes

2

Visually inspect the disc brake pads for the following conditions:

Refer to Brake Pad Inspection .

    • Lining thickness below specifications
    • Uneven and/or abnormal wear - edge-to-edge and/or side-to-side
    • Looseness or damage - including brake pad hardware
    • Evidence of contamination from an external substance

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

3

Are any of the front disc brake pads contaminated?

Go to Step 8

Go to Step 4

4

Are any of the front disc brake pads worn unevenly?

Go to Step 7

Go to Step 5

5

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

Go to Step 7

Go to Step 6

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 .

Did you complete the inspection and replacement?

Go to Step 12

7

    Caution: Support the brake calliper 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 calliper in this manner will cause the flexible brake hose to bear the weight of the calliper, 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 callipers.

  1. Remove the front brake calliper, as appropriate, from the mounting bracket and support the brake calliper. Refer to Front Brake Caliper Replacement .
  2. Inspect the disc brake calliper mounting bracket and the mounting/sliding hardware for the following conditions:
  3. • Binding or seized hardware
    • Worn, damaged or missing hardware components
    • Loose, bent, cracked, or damaged brake calliper mounting bracket
  4. Replace components as required. Refer to Front Brake Caliper Bracket Replacement
  5. Replace the unevenly-worn, loose or damaged disc brake pads as a complete axle set. Refer to Front Disc Brake Pads Replacement .

Did you complete the inspection and replacement?

Go to Step 12

8

  1. Inspect the disc brake callipers, 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:

Did you find and correct the source of the leak causing contamination of the brake 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 brake pads. Refer to Front Wheel Drive Shaft Outer Joint Replacement .

Did you find and correct the source of the leak causing contamination of the brake 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. Replace any components found to be leaking 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

11

  1. Clean the remaining disc brake system components to remove any traces of the contaminant.
  2. Caution: Support the brake calliper 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 calliper in this manner will cause the flexible brake hose to bear the weight of the calliper, 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 callipers.

  3. Remove the front disc brake calliper from the brake calliper mounting bracket and support the brake calliper. Refer to Front Brake Caliper Replacement .
  4. Inspect the disc brake calliper mounting/sliding hardware for the following conditions:
  5. Refer to Front Disc Brake Mounting and Hardware Inspection .

    • Binding or seized hardware
    • Distorted, worn, damaged or missing hardware components
  6. Replace the brake mounting/sliding hardware components as required. Refer to Front Disc Brake Mounting and Hardware Inspection .
  7. Replace the contaminated brake pads as a complete axle set. Refer to Front Disc Brake Pads Replacement .

Did you complete the cleaning, inspection and replacement?

Go to Step 12

12

  1. Check the thickness of each of the disc brake rotors.
  2. Note: Make the following determination and answer the question individually for EACH rotor.

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

Refer to Brake Disc Thickness Measurement .

Does the brake rotor meet the minimum requirements for REFINISHING?

Go to Step 13

Go to Step 16

13

Note: Make the following determination and answer the question individually for EACH rotor.

Inspect each of the 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 15

Go to Step 14

14

  1. Inspect each of the brake rotors for the following surface and wear conditions:
  2. 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.

  3. Make a determination for each brake rotor if the brake rotor requires refinishing based upon the results of the inspection.
  4. If the brake rotor exhibits any of the conditions listed previously, it requires refinishing.

Does the brake rotor require REFINISHING?

Go to Step 15

Go to Step 20

15

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

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

Go to Step 20

Go to Step 19

16

Is the brake disc at or below the DISCARD requirements?

Go to Step 19

Go to Step 17

17

Note: Make the following determination and answer the question individually for EACH rotor.

Inspect each of the 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 19

Go to Step 18

18

  1. Inspect each of the brake rotors for the following surface and wear conditions:
  2. 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.

  3. Make a determination for each brake rotor if the rotor requires replacement based upon the results of the inspection.
  4. If the brake rotor exhibits any of the conditions listed previously, it requires replacement.

Does the brake rotor require REPLACEMENT?

Go to Step 19

Go to Step 20

19

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

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

Did you complete the replacement?

Go to Step 22

20

Note: Make the following determination and answer the question individually for EACH rotor.

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

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

Go to Step 21

Go to Step 22

21

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

Did you complete the operation?

Go to Step 22

22

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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