| 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. |
| 1 |
Were you sent here from the Hydraulic Brake Symptom table? |
Go to Step 2 |
Go to Diagnostic Starting Point - Hydraulic Brakes |
| 2 |
Inspect the travel and feel of brake pedal applies. Perform the following:
- Ensure the ignition is OFF for at least 60 seconds to depressurize 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 |
- Inspect the hydraulic brake system for the conditions listed, based on the following symptoms observed during the pedal travel and feel inspections:
- Pedal feel was spongy
- 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 caliper pistons
- 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 |
| 4 |
- 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 5 |
| 5 |
Inspect for proper brake pedal travel. Refer to Brake Pedal Travel Measurement and Inspection (Without RPO HP5) or Brake Pedal Travel Measurement and Inspection (With RPO HP5) .
Is the brake pedal travel distance within the acceptable limits? |
Go to Step 8 |
Go to Step 6 |
| 6 |
- Inspect for worn, missing, misaligned, bent or damaged brake pedal system components.
- For the brake pedal pushrod component inspection, refer to Brake Pedal Pushrod Inspection .
- 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 7 |
| 7 |
- Replace the brake master cylinder assembly.
- Inspect the brake pedal travel. Refer to Brake Pedal Travel Measurement and Inspection (Without RPO HP5) or Brake Pedal Travel Measurement and Inspection (With RPO HP5) .
Did you find and correct a condition? |
Go to Step 9 |
Go to Step 8 |
| 8 |
- 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 Assist System Diagnosis .
Did you find and correct a condition? |
Go to Step 9 |
Go to Diagnostic Starting Point - Hydraulic Brakes |
| 9 |
- 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 |