Kia Cadenza: Brake System / Brake Booster Repair procedures

Kia Cadenza YG 2016-2025 Service Manual / Brake System / Brake System / Brake Booster Repair procedures

Brake Booster Operating Test

For simple checking of the brake booster operation, carry out the following tests.

1.	Run the engine for one or two minutes, and then stop it. If the pedal depresses fully the first time but gradually becomes higher when depressed succeeding times, the booster is operating properly, if the pedal height remains unchanged, the booster is inoperative.

2.	With the engine stopped, step on the brake pedal several times. Then step on the brake pedal and start the engine. If the pedal moves downward slightly, the booster is in good condition. If there is no change, the booster is inoperative.

With the engine running, step on the brake pedal and then stop the engine.Hold the pedal depressed for 30 seconds. If the pedal height does not change, the booster is in good condition, if the pedal rises, the booster is inoperative.

If the above three tests are okay, the booster performance can be determined as good.

Even if one of the above three tests is not okay, check the check valve, vacuum hose and booster for malfunction.

Removal

1.	Turn ignition switch OFF and disconnect the negative (-) battery cable.

2.	Remove the air duct (B) and air cleaner assembly (A).

3.	Disconnect a connector and loosen the wiring harness mounting nuts. Then pivot the wiring harness (A) side out of the way.

4.	Disconnect the brake fluid level switch connector (A), and remove the reservoir cap.

Remove the brake fluid from the master cylinder reservoir with a syringe.

•	Do not spill brake fluid on the vehicle, it may damage the paint ; if brake fluid does contact the paint, wash if off immediately with water.

Remove the brake tube (A).

Tightening torque:

ABS : 12.7 ~ 16.7 N.m (1.3 ~ 1.7 kgf.m, 9.4 ~ 12.3 lb-ft)

ESP : 18.6 ~ 22.6 N.m (1.9 ~ 2.3 kgf.m, 13.7 ~ 16.6 lb-ft)

Remove the master cylinder (B) from the brake booster after loosening the mounting nuts (A).

Tightening torque:

9.8 ~ 15.6 N.m (1.0 ~ 1.6 kgf.m, 7.2 ~ 11.6 lb-ft)

8.	Disconnect the vacuum hose (A) from the brake booster.

9.	Remove the snap pin (B) and clevis pin (A).

10.

Remove the mounting nuts.

Tightening torque:

12.7 ~ 15.7 N.m (1.3 ~ 1.6 kgf.m, 9.4 ~ 11.6 lb-ft)

11.

Disconnect the brake tubes from the HECU by unlocking the nuts (B) counterclockwise with a spanner.

Tightening torque :

12.7 ~ 16.7 N.m (1.3 ~ 1.7 kgf.m, 9.4 ~ 12.3 lb-ft)

12.	Remove the brake booster.

Inspection

Inspect the check valve in the vacuum hose.

Do not remove the check valve from the vacuum hose.

2.	Check the boot for damage.

Installation

Installation is the reverse of removal.

•	Before installing the pin, apply the grease to the joint pin.

•	Use a new snap pin whenever installing.

2.	After installing, bleed the brake system. (Refer to Brake system bleeding)

Brake Booster Components and Components Location

Components 1. Brake booster2. Master cylinder assembly3. O-ring ...

Master Cylinder Components and Components Location

Components 1. Reservoir cap2. Reservoir3. Grommet4. Master cylinder ...

Other information:

Kia Cadenza YG 2016-2025 Owners Manual: Adding equipment to or modifying your air bag-equipped vehicle. Air bag warning label

Adding equipment to or modifying your air bag-equipped vehicle If you modify your vehicle by changing your vehicle's frame, bumper system, front end or side sheet metal or ride height, this may affect the operation of your vehicle's air bag system. Air bag warning label Air bag warn ...

Kia Cadenza YG 2016-2025 Service Manual: Troubleshooting

Trouble Symptom Charts Trouble Symptom 1 Trouble Symptom 2 Trouble symptomProbable causeRemedyThe set vehicle speed varies greatly upward or downward"Surging" (repeated alternating acceleration and deceleration) occurs after settingMalfunction of the vehicle speed sensor circuitRepair the v ...