Kia Optima Hybrid: Brake System / Troubleshooting

Troubleshooting
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

   
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
Special Service Tools

Special Service Tools Tool Name / NumberIllustrationDescription09581-11000Piston expanderUsed when spreading the front and rear brake piston.09580-3D100Air bleeding toolUsed when bleeding the air in the ...

AHB(Active Hydraulic Boost) System

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Other information:

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual: High Voltage Shut-off Procedures


High Voltage Shut-off Procedures     Be sure to read and follow the “General Safety Information and Caution” before doing any work related with the high voltage system. Failure to follow the safety instructions may result in serious electrical injuries.     • High voltage components: ...

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual: Special Service Tools


Special Service Tools Tool Name / NumberIllustrationDescriptionRKE Battery Checker09954-2P100Measuring the RKE batteryvoltage Personal Protective Equipment NameIllustrationDescriptionInsulation gloveUsed when inspecting or working on the high voltage components[Insulation performance : 1000V / 300A or ...

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