Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: TRAC does not Operate

DESCRIPTION

When TRAC or VSC is operating, the skid control ECU (brake actuator 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 TRAC OFF message and the VSC OFF indicator light illuminates to inform the driver.

When a communication malfunction with the ECM 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 actuator assembly), perform "Calibration".

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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 (combination switch assembly) when TRAC did not operate.

OK:

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

HINT:

When the multi-information display in the combination meter assembly displays TRAC OFF message, TRAC does not operate.

OK

END

NG

(a) Connect the Techstream to the DLC3.

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

(c) Read the DTCs following the prompts on the Techstream. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

(d) Check the DTCs that are output.

OK:

DTCs are not output.

(e) Operate the VSC OFF switch (combination switch assembly) and check that the multi-information display in the combination meter assembly displays TRAC OFF message 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 TRAC OFF message and the VSC OFF indicator light illuminates in accordance with the operation of the switch.

NG

INSPECT COMBINATION SWITCH ASSEMBLY

OK

(a) Enter the following menus: Chassis / Brake/EPB / Utility / Signal Check.

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

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OK:

Speed sensor Dealer 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 (combination switch assembly) 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.

OK

USE SIMULATION METHOD TO CHECK

NG

REPLACE BRAKE ACTUATOR ASSEMBLY