Toyota Avalon (XX50): Brake Actuator Operation Sound is Loud during Initial Check. Brake Hold Operated Indicator Light Circuit. Brake Hold Standby Indicator Light Circuit

Brake Actuator Operation Sound is Loud during Initial Check

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

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PROCEDURE

(a) After turning the engine switch on (IG), compare the operating sound of the brake actuator the first time the vehicle speed reaches 45 km/h (28 mph) with a known good vehicle of the same model.

OK:

The operating sound is the same or quieter than that of a known good vehicle of the same model.

HINT:

When the vehicle speed reaches approximately 40 km/h (25 mph), the initial check of the brake actuator assembly is performed and pump motor operation sounds are generated.

OK

END

NG

(a) Check that the cushion of the brake actuator bracket assembly is not worn, damaged or deformed.

OK:

The brake actuator bracket assembly is not worn, damaged or deformed.

NG

REPLACE BRAKE ACTUATOR BOLT CUSHION

OK

(a) Drain the brake fluid.

(b) Disconnect all brake lines from the brake actuator assembly.

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(c) Connect each brake line so that the cushion of the brake actuator assembly is tensioned evenly.

Click here

NOTICE:

After connecting all the brake lines, add brake fluid and bleed the brake system.

Click here

HINT:

By reducing the tension on the brake lines and cushion, the operating sound of the brake actuator assembly may be reduced.

(d) Check that no brake lines interfere with the vehicle body or other components.

NEXT

(a) Perform a road test and check the magnitude of the operating sound again.

OK:

The operating sound is the same or quieter than that of a known good vehicle of the same model.

OK

END

NG

REPLACE BRAKE ACTUATOR ASSEMBLY

Brake Hold Operated Indicator Light Circuit

DESCRIPTION

The brake hold operated indicator light illuminates when the brake hold system is operating (vehicle stopped due to 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 (electric parking brake switch assembly) is pressed, the brake hold operated indicator light blinks.

• Vehicle Conditions:
  1. The driver door is closed.
  2. The driver seat belt is fastened.

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

Click here

PROCEDURE

(a) Check that the brake hold standby indicator light operates normally.

(b) If the brake hold operated indicator light does not illuminate even though the brake hold standby indicator light is illuminated, check that the following brake hold operation (brake fluid pressure is being maintained ) conditions are met.

1. The shift lever is not in P or R.
2. The vehicle is fully stopped and the driver is depressing the brake pedal.
3. The driver is not depressing the accelerator pedal.
4. The vehicle is not on a steep incline.

HINT:

When a malfunction occurs in the brake control system, the brake hold operated indicator light blinks.

NEXT

(a) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(b) Perform the Active Test of the combination meter assembly using the Techstream.

(c) Check the combination meter assembly.

OK:

The brake hold operated indicator light turns on or off in accordance with the Techstream operation.

NG

INSPECT METER / GAUGE SYSTEM

OK

(a) Enter the following menus: Chassis / ABS/VSC/TRAC/EPB / Active Test.

(b) Check the operating condition of the brake hold operated indicator light when operating it using the Techstream.

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

USE SIMULATION METHOD TO CHECK

Brake Hold Standby Indicator Light Circuit

DESCRIPTION

The brake hold standby indicator light turns on if brake hold control is possible when the following conditions required for operation standby are met and the brake hold switch (electric parking brake switch assembly) is pressed while the engine switch is on (IG).

• Conditions required for operation standby:
  1. The driver door is closed.
  2. The driver seat belt is fastened.
  3. The system is normal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

Click here

PROCEDURE

(a) If the brake hold standby indicator light does not illuminate even though the brake hold switch (electric parking brake switch assembly) is pushed, check that the brake hold function operation conditions are met.

1. The driver door is closed.
2. The driver seat belt is fastened.
3. The system is normal.

NEXT

(a) Check if CAN communication system DTCs are output.

Click here

B

CHECK CAN COMMUNICATION SYSTEM

A

(a) Check if the skid control ECU (brake actuator assembly) connector is securely connected.

OK:

The connector is securely connected.

NG

CONNECT CONNECTOR TO BRAKE ACTUATOR ASSEMBLY CORRECTLY

OK

(a) Turn the engine switch off.

(b) Enter the following menus: Body Electrical / Combination Meter / Active Test.

(c) Perform the Active Test of the combination meter assembly using the Techstream.

(d) Check the combination meter assembly.

OK:

The brake hold standby indicator light turns on or off in accordance with the Techstream operation.

NG

INSPECT METER / GAUGE SYSTEM

OK

(a) Enter the following menus: Chassis / ABS/VSC/TRAC/EPB / Active Test.

(b) Check the operating condition of the brake hold standby indicator light when operating it using the Techstream.

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

(a) Turn the engine switch off.

*a Component without harness connected (Brake Hold Switch (Electric Parking Brake Switch Assembly))

(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(c) Disconnect the G24 brake hold switch (electric parking brake switch assembly) connector.

(d) Check both the connector case and the terminal for deformation and corrosion.

OK:

No deformation or corrosion.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

NG

REPLACE ELECTRIC PARKING BRAKE SWITCH ASSEMBLY

OK

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.

OK:

The connector is securely connected.

(b) Disconnect the A28 skid control ECU (brake actuator assembly) connector.

(c) Check both the connector case and the terminal for deformation and corrosion.

OK:

No deformation or corrosion.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR