Brake System: Troubleshooting
WARNING: This page is about a different car, the 2015 Kia Soul EV. However, it is still accessible from the selected car via links, so may be relevant.
BRAKE SYSTEM TROUBLESHOOTING
| Symptom | Possible Cause | Remedy |
|---|---|---|
| Lower pedal or spongy pedal | 1. Integrated Brake Actuation Unit (Air in system) | Bleed air |
| 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 (Stuck) | 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) Bleed | air | |
| 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 (Loose) | 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 (Damaged) | 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 (Damaged) | Replace | |
| 4. Master cylinder cap seal | Replace | |
| 5. Damaged brake lines | Replace | |
| Heavy pedal (Halt) | 1. Brake pedal stuck (Lack of grease) | Repair |
| 2. IBAU (Inoperative) | Replace | |
| Noisy electric motor and/or excessive braking force after 2 - 3 consecutive applications of brake pedal | 1. AHB system (air in system) | Bleed air |
| (When accumulator pressure increase rate is below 5bar/sec when sensor data was inspected after connecting to AHB module) | 2. PSU(Inoperative) | Replace |
| Excessive noise when pushing brake pedal | 1. IBAU/PSU system (air in system) | Bleed air |
NOTE:
The following operations may generate brake motor sound which is considered normal:
- Repeated pushing on brake pedal
- Pushing and releasing brake pedal during power off
- Opening driver side door
The following cases are normal although the brake pedal may seem abnormal:
- Noise when brake pedal is abruptly pushed
- Noise when brake pedal is consecutively pushed