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
Diagnostic Starting Point - Hydraulic Brakes
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2
| Inspect the travel and feel of brake pedal applies. Perform the following:
- Apply the brake pedal several times to fully deplete the power reserve.
- 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 |
- | Binding wheel cylinder pistons, if equipped |
• | Pedal returned to rest slowly after any of the applies. |
- | Internally damaged flexible brake hoses; hindering fluid return |
- | Binding caliper pistons |
- | Binding wheel cylinder pistons, if equipped |
- | Internal brake fluid leaks; improperly functioning master cylinder |
- Repair or replace components as necessary. Refer to
Hydraulic 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 4
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4
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- Inspect the drum brake system, if equipped, for the following conditions:
• | Improper adjustment or improper adjuster operation |
• | Glazed or excessively worn linings |
• | Cracked, distorted or damaged linings |
• | Cracked, excessively worn, distorted or damaged drums |
• | Bell-mouth or barrel-shaped drum friction surface |
• | Hard spots, heat checks, blueing discoloration of drum friction surface |
- Adjust, repair or replace components as necessary. Refer to
Drum 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
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5
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- Inspect the disc brake system for the following conditions:
• | Cracked, excessively worn or damaged linings |
• | Cracked, excessively worn or damaged rotors |
• | Improperly operating, binding or damaged caliper hardware and/or lining hardware |
• | Loose or missing caliper hardware and/or lining hardware |
• | Excessive assembled lateral runout (LRO) of rotor friction surfaces |
• | Bent or damaged caliper 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 6
|
6
| 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 7
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7
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- Inspect for worn, missing, misaligned, bent or damaged brake pedal system components.
• | Inspect the brake pedal bushings 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 8
|
8
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- Inspect the brake assist system for the following conditions:
• | Vacuum leaks and/or improperly operating check valve, if equipped with vacuum assist |
• | Power steering fluid leaks, if equipped with hydraulic power assist |
• | Damaged or improperly operating brake booster assembly |
- Adjust, repair or replace components as necessary. Refer to
Brake Assist System Diagnosis
.
Did you find and correct a condition?
| Go to
Step 9
| Go to
Diagnostic Starting Point - 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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