Lexus ES: Brake Hold Operated Indicator Light Circuit
DESCRIPTION
The brake hold operated indicator light illuminates when the brake hold system is operating (vehicle stopped via brake fluid pressure hold) and turns off when the brake hold system operation is finished (brake fluid pressure decreases).
The brake hold system may not operate depending on vehicle conditions even when the system is in standby mode and the brake hold standby indicator light is illuminated.
If there is a system malfunction that causes brake hold control to be prohibited, when the vehicle is under the following conditions and the brake hold switch (No. 3 combination switch assembly) is turned on, the brake hold operated indicator light blinks.
-
Vehicle Conditions:
- The driver side door is closed.
- The driver side seat belt is fastened.
HINT:
- When the power switch is turned off during brake hold operation, control stops.
-
If brake hold control does not operate even when the vehicle stops, depress on the brake pedal again firmly to stop the vehicle.
If brake hold control still does not operate, confirm the conditions for brake hold control to operate.
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. | PRE-CHECK |
(a) Check that the brake hold standby indicator light operates normally.
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(b) If the brake hold operated indicator light does not illuminate although the brake hold standby indicator light is illuminated, check that the following brake hold operation (maintaining brake fluid pressure) conditions are met.
- System is in operation standby state (brake hold standby indicator light is illuminated).
- Shift position is not P or R.
- Driver is depressing brake pedal and vehicle is fully stopped.
- Driver is not depressing accelerator pedal.
- Vehicle is not on steep decline.
HINT:
If a malfunction occurs in one of the following systems, the brake hold operated indicator light will blink. If this occurs, perform troubleshooting on the malfunctioning system.
- Brake system
- Electric parking brake system
- Hybrid control system
|
| 2. | INSPECT COMBINATION METER ASSEMBLY |
(a) Turn the power switch off.
(b) Perform the Active Test of the combination meter assembly (meter CPU) using the Techstream.
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| Tester Display |
|---|
| Hold Indicator |
(c) Check the combination meter assembly.
OK:
The brake hold operated indicator light turns on or off in accordance with Techstream operation.
| NG |  | INSPECT METER / GAUGE SYSTEM |
|
| 3. | PERFORM ACTIVE TEST USING TECHSTREAM (BRAKE HOLD OPERATED INDICATOR LIGHT) |
(a) Select the Active Test on the Techstream.
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| Tester Display | Measurement Item | Control Range | Diagnostic Note |
|---|---|---|---|
| BH Operated Light | Brake hold operated indicator light | Indicator light ON/OFF | Observe combination meter assembly |
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| BH Operated Light | Brake hold operated indicator light | ON or OFF | ON: Indicator light on OFF: Indicator light off | - |
| Active Test Display |
|---|
| BH Operated Light |
| Data List Display |
|---|
| BH Operated Light |
(b) Check the operating condition of the brake hold operated indicator light when operating it using the Techstream.
| Result | Proceed to |
|---|---|
| Brake hold operated indicator light in the Data List does not change using the Active Test. | A |
| Brake hold operated indicator light in the Data List turns ON/OFF using the Active Test. | B |
| A | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
| B | | USE SIMULATION METHOD TO CHECK |
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