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Step
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Action
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Yes
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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
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Were you sent here from the Hydraulic Brake Symptom table?
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Go to
Step 2
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Go to
Diagnostic Starting Point - Vehicle
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2
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Inspect the travel and feel of brake pedal applies. Perform the following:
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1.
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Apply the brake pedal several times to fully deplete the power reserve.
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2.
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With power reserve depleted, apply the brake pedal with light, steady pressure and hold for 15 seconds. Observe pedal travel and feel.
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3.
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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.
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4.
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Apply the brake pedal slowly, then release and apply the pedal quickly. Observe pedal travel and feel for each apply.
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Did you complete the brake pedal travel and feel inspections?
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Go to
Step 3
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-
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3
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1.
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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:
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Air in hydraulic system
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External brake fluid leaks
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Soft, weak or damaged hydraulic hoses; expanding under pressure
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•
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Pedal fell away and/or traveled to or almost to floor
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External brake fluid leaks
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Poor brake fluid quality; low boiling point
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Internal brake fluid leaks; improperly functioning master cylinder
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•
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Pedal was somewhat firm then dropped slightly, or pedal rose with successive applies, or pedal travel was different between slow and quick applies
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Internal brake fluid leaks; improperly functioning master cylinder
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Poor brake fluid quality; low boiling point
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Pedal returned to rest slowly after any of the applies
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Internally damaged flexible brake hoses; hindering fluid return
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Binding caliper pistons
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Internal brake fluid leaks; improperly functioning master cylinder
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3.
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Re-inspect brake pedal apply travel and feel.
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Did you find and correct a condition?
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Go to
Step 8
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Go to
Step 4
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4
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1.
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Inspect the disc brake system for the following conditions:
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Cracked, excessively worn or damaged linings
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Cracked, excessively worn or damaged rotors
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Improperly operating, binding or damaged caliper hardware and/or lining hardware
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Loose or missing caliper hardware and/or lining hardware
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Excessive assembled lateral runout (LRO) of rotor friction surfaces
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Bent or damaged caliper or mounting component
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3.
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Re-inspect brake pedal apply travel and feel.
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Did you find and correct a condition?
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Go to
Step 8
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Go to
Step 5
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5
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Inspect for proper brake pedal travel. Refer to
Brake pedal travel measurement and inspection
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Is the brake pedal travel distance within the acceptable limits?
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Go to
Step 7
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Go to
Step 6
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6
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1.
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Inspect for worn, missing, misaligned, bent or damaged brake pedal system components.
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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.
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2.
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Replace the brake pedal system components that are worn, missing, misaligned, bent or damaged.
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Did you find and replace any worn, missing, misaligned, bent or damaged brake pedal system components?
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Go to
Step 8
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Go to
Step 7
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7
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1.
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Inspect the brake assist system for the following conditions:
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Vacuum leaks and/or improperly operating check valve, if equipped with vacuum assist
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Power steering fluid leaks, if equipped with hydraulic power assist
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Damaged or improperly operating brake booster assembly
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Did you find and correct a condition?
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Go to
Step 8
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Go to
Diagnostic Starting Point - Vehicle
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8
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1.
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Install or connect components that were removed or disconnected during diagnosis.
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Is the condition still present?
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Go to
Step 2
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System OK
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