Toyota Avalon Service & Repair Manual: Excessive Brake Pedal Travel (No Fluid Leaks and No Air in System)

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

1.

PRE-INSPECTION

(a) Brake pedal inspection

(1) Perform a visual inspection and operate the brake pedal to check for any malfunctions.

(2) Check the brake pedal height, brake pedal free play and brake pedal reserve distance.

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HINT:

If the brake pedal height is not within specification, confirm that there are no other malfunctions before adjusting the brake pedal height.

(b) Brake inspection

(1) Check that the disc brake pads of each wheel are installed correctly.

(2) Check that the bleeder plug and union bolt is not loose, and that there are no damaged gaskets or brake fluid leaks, for each wheel cylinder.

(c) Brake fluid leaks and air in brake line inspection

(1) Check and take a note of the fluid level in the brake master cylinder reservoir assembly.

(2) Repeatedly depress the brake pedal and confirm that the brake pedal feels normal (no air in the system, etc.).

(3) Check if the brake fluid level in the brake master cylinder reservoir assembly has changed.

(4) If the brake fluid level has decreased, check for leaks due to damaged brake lines or hoses, loose union nuts, damaged brake master cylinder sub-assembly seals, etc.

(d) Bleeding air from brake system

(1) Bleed air from the brake lines and brake actuator assembly.

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NEXT

2.

PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

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

Chassis > ABS/VSC/TRAC/EPB > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Motor Relay

ABS motor relay

Relay OFF/ON

Operating sound of motor can be heard

Chassis > ABS/VSC/TRAC/EPB > Active Test

Tester Display

Motor Relay

(d) Fully depress and hold the brake pedal.

HINT:

Make sure that the brake pedal has travelled excessively before holding it depressed.

(e) Operate the ABS motor relay using the Active Test and check if the brake pedal height changes when the pump motor is operating.

OK:

The brake pedal height does not change (the brake pedal travel remains excessive).

NG

REPLACE BRAKE ACTUATOR ASSEMBLY

OK

3.

CHECK BRAKE MASTER CYLINDER SUB-ASSEMBLY

(a) Check that there are no brake fluid leaks and no indications of a malfunction in the brake master cylinder sub-assembly.

OK:

There are no brake fluid leaks and no indications of a malfunction in the brake master cylinder sub-assembly.

NG

REPLACE BRAKE MASTER CYLINDER SUB-ASSEMBLY

OK

4.

INSPECT BRAKE BOOSTER ASSEMBLY

(a) Inspect operation of the brake booster assembly.

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OK:

The brake booster assembly is normal.

OK

USE SIMULATION METHOD TO CHECK

NG

REPLACE BRAKE BOOSTER ASSEMBLY

    Dtc Check / Clear

    Fail-safe Chart

    See More:

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