Step
| Action
| Yes
| No
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DEFINITION: Brake pedal travels further than expected to obtain firm pedal and/or firm pedal cannot be obtained, pedal fades away, or pedal is spongy.
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1
| Were you sent here from the Hydraulic Brake Symptom table?
| Go to Step 2
| Go to Symptoms - Hydraulic Brakes
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2
| Inspect the travel and feel of brake pedal applies. Perform the following:
- Ensure the ignition is OFF for at least 60 seconds to depressurise and deplete the power reserve.
- With the ignition OFF, apply the brake pedal several times to verify the power reserve is fully depleted.
- With power reserve depleted, apply the brake pedal with light, steady pressure and hold for 15 seconds. Observe pedal travel and feel.
- Apply the brake pedal with light, steady pressure, then without pumping the pedal, reduce pressure and reapply pressure several times. Observe pedal travel and feel for each apply.
- Apply the brake pedal slowly, then release and apply the pedal quickly. Observe pedal travel and feel for each apply.
Did you complete the brake pedal travel and feel inspections?
| Go to Step 3
| --
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3
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- Inspect the hydraulic brake system for the conditions listed, based on the following symptoms observed during the pedal travel and feel inspections:
- | Air in hydraulic system |
- | External brake fluid leaks |
- | Soft, weak or damaged hydraulic hoses; expanding under pressure |
• | Pedal fell away and/or traveled to or almost to floor |
- | External brake fluid leaks |
- | Poor brake fluid quality; low boiling point |
- | Internal brake fluid leaks; improperly functioning master cylinder |
• | Pedal was somewhat firm then dropped slightly, or pedal rose with successive applies, or pedal travel was different between slow and quick applies |
- | Internal brake fluid leaks; improperly functioning master cylinder |
- | Poor brake fluid quality; low boiling point |
• | Pedal returned to rest slowly after any of the applies |
- | Internally damaged flexible brake hoses; hindering fluid return |
- | Binding calliper pistons |
- | Internal brake fluid leaks; improperly functioning master cylinder |
- Repair or replace components as necessary. Refer to Brake Hydraulic and Assist System Diagnosis .
- Re-inspect brake pedal apply travel and feel.
Did you find and correct a condition?
| Go to Step 9
| Go to Step 4
|
4
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- Inspect the disc brake system for the following conditions:
• | Cracked, excessively worn or damaged linings |
• | Cracked, excessively worn or damaged discs |
• | Improperly operating, binding or damaged calliper hardware and/or lining hardware |
• | Loose or missing calliper hardware and/or lining hardware |
• | Excessive assembled lateral runout (LRO) of disc friction surfaces |
• | Bent or damaged calliper or mounting component |
- Adjust, repair or replace components as necessary. Refer to Disc Brake System Diagnosis .
- Re-inspect brake pedal apply travel and feel.
Did you find and correct a condition?
| Go to Step 9
| Go to Step 5
|
5
| Inspect for proper brake pedal travel. Refer to Brake Pedal Travel Measurement and Inspection .
Is the brake pedal travel distance within the acceptable limits?
| Go to Step 8
| Go to Step 6
|
6
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- Inspect for worn, missing, misaligned, bent or damaged brake pedal system components.
- Inspect the brake pedal bushes for binding, excessive wear and/or damage and inspect the brake pedal for a misaligned, bent, and/or damaged condition.
- Replace the brake pedal system components that are worn, missing, misaligned, bent or damaged.
Did you find and replace any worn, missing, misaligned, bent or damaged brake pedal system components?
| Go to Step 9
| Go to Step 7
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7
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- Replace the brake master cylinder assembly.
- Inspect the brake pedal travel. Refer to Brake Pedal Travel Measurement and Inspection .
Did you find and correct a condition?
| Go to Step 9
| Go to Step 8
|
8
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- Inspect the brake assist system for the following conditions:
• | Internal fluid leaks and/or restrictions within the brake modulator assembly |
• | Damaged or improperly operating brake modulator assembly |
- Adjust, repair or replace components as necessary. Refer to Brake Hydraulic and Assist System Diagnosis .
Did you find and correct a condition?
| Go to Step 9
| Go to Symptoms - Hydraulic Brakes
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9
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- Install or connect components that were removed or disconnected during diagnosis.
- Road test the vehicle in order to confirm proper operation. Refer to Brake System Vehicle Road Test .
Is the condition still present?
| Go to Step 2
| System OK
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