Lexus ES: 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 "Traction Control Turned Off" 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 acceleration sensor zero point calibration and store system information memorization.
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PROCEDURE
| 1. | BRAKE PROBLEM CHECK |
(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.
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| 2. | CHECK DTC |
(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.
Chassis > Brake/EPB > Trouble Codes(d) Check the DTCs (electronically controlled brake system) that are output.
| Result | Proceed to |
|---|---|
| DTCs are not output. | A |
| Electronically controlled brake system DTCs are output. | B |
| B | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
|
| 3. | CHECK VEHICLE |
(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 |
|
| 4. | PERFORM DEALER MODE (SIGNAL CHECK) INSPECTION (SPEED SENSOR CHECK) |
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Enter the following menus: Chassis / Brake/EPB / Utility / Signal Check.
(d) 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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| Tester Display |
|---|
| Signal Check |
OK:
Speed sensor Dealer Mode (Signal Check) inspection items change from incomplete to complete.
| NG | | INSPECT AND REPAIR MALFUNCTIONING SPEED SENSOR CIRCUIT |
|
| 5. | PERFORM OPERATION CHECK DRIVING |
(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.
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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 Vehicle Control History when the system operated.
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- 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 ACTUATOR ASSEMBLY |
READ NEXT:
Control Module Communication Bus "B" Off Bus Off (U007488,...,U015187)
DESCRIPTION The skid control ECU (brake actuator assembly) communicates with the following ECUs and sensors via CAN communication.
ECM
TCM (ECM)
Yaw rate and acceleration sensor (airbag ECU ass
Utility
UTILITY DESCRIPTION (a) Refer to the table below and then perform the necessary operation according to the part to be replaced in order to perform calibration. Parts to be Replaced / Operation Ne
Vehicle Control History
VEHICLE CONTROL HISTORY DESCRIPTION
Vehicle Control History is a function that captures and stores ECU data when triggered by specific vehicle behavior.
It may be possible to determine the cause
SEE MORE:
Installation
INSTALLATION CAUTION / NOTICE / HINT HINT:
Use the same procedure for the RH side and LH side.
The following procedure is for the LH side.
PROCEDURE 1. TEMPORARILY INSTALL REAR AXLE CARRIER SUB-ASSEMBLY (a) Temporarily install the rear axle carrier sub-assembly to the rear shock absorber
Removal
REMOVAL CAUTION / NOTICE / HINT The necessary procedures (adjustment, calibration, initialization, or registration) that must be performed after parts are removed and installed, or replaced during rear drive shaft assembly removal/installation are shown below. Necessary Procedures After Parts Remove
