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Brake System: Troubleshooting

WARNING: This page is about a different variant/trim than selected.
Symptom Suspect Area Reference
Lower pedal or spongy pedal 1. Integrated Brake Actuation Unit (Air in) air - bleed
2. AHB system (Fluid leaks) replace
3. Piston seals in IBAU (Worn or damaged) replace
Brake drag 1. Brake pedal free play (Minimum) adjust
2. Pad or lining (Cracked or distorted) replace
3. Piston (Stuck) replace
4. Piston (Frozen) replace
5. Anchor or Return spring (Inoperative) replace
6. Master cylinder (Inoperative) replace
7. IBAU (Inoperative) replace
Brake pull 1. Piston (Sticking) replace
2. Pad or lining (Oily) replace
3. Piston (Frozen) replace
4. Disc (Scored) replace
5. Pad or lining (Cracked or distorted) replace
Hard pedal but brake inefficient 1. Brake system (Fluid leaks) repair
2. Brake system (Air in) air - bleed
3. Pad or lining (Worn) replace
4. Pad or lining (Cracked or distorted) replace
5. Rear brake shoe clearance(Out of adjustment) adjust
6. Pad or lining (Oily) replace
7. Pad or lining (Glazed) replace
8. Disc (Scored) replace
9. IBAU (Inoperative) replace
10. PSU (Inoperative) replace
Noise from brake 1. Pad or lining (Cracked or distorted) replace
2. Installation bolt (Loosen) adjust
3. Disc (Scored) replace
4. Sliding pin (Worn) replace
5. Pad or lining (Dirty) clean
6. Pad or lining (Glazed) replace
7. Brake pad shim (Damage) replace
Brake fades 1. Pad or lining (Worn) replace
2. Master cylinder (Inoperative) replace
Brake vibration, pulsation 1. Pedal free play adjust
2. Master cylinder (Inoperative) replace
3. Caliper (Damage) replace
4. Master cylinder cap seal replace
5. Damaged brake lines replace
Heavey pedal (Halt) 1. Brake pedal sticking (lack of grease) repair
2. IBAU (Inoperative) replace
Motor sounds and excessive time to braking when consecutive 2 or 3 times pushing brake pedal (In the case of that accumulator pressure increase rate is under 5bar/sec when checking sensor figures of AHB with GDS) 1. AHB system (air in) air - bleed
2. PSU(Inoperative) replace
Excessive noise when pushing brake pedal 1. IBAU/PSU system (air in) air - bleed
NOTE: It is not the malfunction of brake when motor sound is noticed with followings.
  • Repeated pushing brake pedal
  • Pushing and releasing brake pedal with power off.
  • Opening a door of driver side

It is not the malfunction of brake while a brake pedal seems inoperative with followings.
  • Noise when pushing brake pedal fast
  • Noise when pushing brake pedal consecutively