Lexus ES: Excessive Brake Pedal Travel (No Fluid Leaks and No Air in System)
DESCRIPTION
Depending on the malfunction, the skid control ECU (brake booster with master cylinder assembly) prohibits operation of the electronically controlled brake system to protect components and prevent incorrect operation when DTCs are stored.
If the switching solenoid is disabled due to prohibition of the electronically controlled brake system, the response of the brake pedal changes and braking performance is reduced.
CAUTION / NOTICE / HINT
NOTICE:
After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".
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PROCEDURE
| 1. | BRAKE PROBLEM CHECK |
(a) Check the conditions at the time the problem occurred.
(1) Whether a warning light illuminated or the buzzer sounded.
(2) Road surface condition when the problem occurred and just before the problem occurred.
(3) When the problem occurred and how many times the brake pedal was depressed before the problem occurred.
(4) Frequency of the abnormal brake pedal response.
|
| 2. | CHECK DTC AND FREEZE FRAME DATA |
(a) Using the Techstream, check DTCs and Freeze Frame Data.
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| Result | Proceed to |
|---|---|
| DTCs are not output. | A |
| DTCs are output. | B |
HINT:
- If there are currently no warnings and the brake pedal travel is not excessive, DTCs may have been cleared after the system returned to normal.
- If the brake pedal response returned to normal and there are currently no warnings, the system is normal.
| B |  | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
|
| 3. | CHECK BRAKE PEDAL |
(a) While depressing the brake pedal by hand, check the installation condition of the brake pedal stroke sensor assembly and brake pedal, and check for mechanical malfunctions.
(b) Check and adjust the brake pedal height.
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|
| 4. | INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
(a) Check the brake booster with master cylinder assembly.
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OK:
The brake booster with master cylinder assembly is normal.
| OK | | USE SIMULATION METHOD TO CHECK |
| NG | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
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