Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: TRAC does not Operate

DESCRIPTION

When ABS, TRAC or VSC is operating, the skid control ECU (brake booster with master cylinder assembly) blinks the slip indicator light to inform the driver that slippage occurred.

When in VSC off mode, or TRAC and VSC are disabled, the multi-information display in the combination meter assembly displays "Traction Control Turned Off" and the VSC OFF indicator light illuminates to inform the driver.

When a communication malfunction with the hybrid vehicle control ECU is detected, TRAC and VSC are disabled. Also when the system is malfunctioning, TRAC and VSC are disabled and the indicator lights of related systems illuminate.

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

(a) Check if the slip indicator light was illuminated when TRAC did not operate.

OK:

The slip indicator light was illuminated.

HINT:

When a DTC is stored, the slip indicator light is illuminated and TRAC does not operate due to the fail-safe function.

(b) Check the operation condition of the VSC OFF switch when TRAC did not operate.

OK:

The VSC OFF switch had been operated to turn off TRAC when TRAC did not operate.

HINT:

When the multi-information display in the combination meter assembly displays "Traction Control Turned Off", TRAC does not operate.

OK

END

NG

(a) Clear the DTCs.

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(b) Turn the power switch off.

(c) Turn the power switch on (IG).

(d) Check the DTCs (electronically controlled brake system) that are output.

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B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

A

(a) Operate the VSC OFF switch and check that the multi-information display in the combination meter assembly displays "Traction Control Turned Off" and the VSC OFF indicator light illuminates in accordance with the operation of the switch.

OK:

The multi-information display in the combination meter assembly displays "Traction Control Turned Off" and the VSC OFF indicator light illuminates in accordance with the operation of the switch.

NG

INSPECT VSC OFF SWITCH CIRCUIT

OK

(a) Using the Techstream, perform a Test Mode (Signal Check) inspection sensor check and check that speed sensor Test Mode (Signal Check) inspection items change from incomplete to complete.

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OK:

Speed sensor Test Mode (Signal Check) inspection items change from incomplete to complete.

NG

INSPECT AND REPAIR MALFUNCTIONING SPEED SENSOR CIRCUIT

OK

(a) Operate the VSC OFF switch and check that the system is not in TRAC off mode or VSC off mode.

(b) Check that no DTCs are output and that each warning light is not illuminated.

(c) Start off the vehicle on a low friction surface and check that TRAC operates when attempting to make the drive wheels slip.

OK:

TRAC operates when slip occurs when starting off.

NOTICE:

• Even when the system is normal, VSC may not operate when the vehicle speed is low or TRAC may not operate due to a malfunction. Make sure that only the drive wheels slip during the procedure.
• When confirming that the slip indicator light blinks, do not slip the drive wheels longer than necessary. Whether TRAC operated or not can be checked by reading the Freeze Frame Data when the system operated.
• Pay attention to your surroundings when performing the procedure and depress the accelerator pedal with caution.

OK

USE SIMULATION METHOD TO CHECK

NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY