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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Steering >> Power Steering >> Power Steering System - Diagnostic Codes & Circuit Tests >> Power Steering System >> Heavy Steering Feel (EPS Warning Light (Yellow)) [11/2023 - ] >> Procedure

Heavy Steering Feel (EPS Warning Light (Yellow)) [11/2023 - ]: Procedure

  1. READ VALUE USING GTS 
    1. Enter the following menus: Chassis / EMPS / Data List.
    2. Read the Data List according to the display on the GTS.

      Chassis > EMPS > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Battery Voltage Drop History Auxiliary battery voltage drop history count 0 to 255 - -
      Engine Revolution Ready Signal Communication Failure History Presence of ignition switch ON (READY) status signal disruption history 0 to 255 - -
      Steering Angle Sensor Signal Communication Failure History Steering angle sensor signal disruption history count 0 to 255 - -
      Vehicle Speed Signal Invalid History Vehicle speed signal invalid history count 0 to 255 - -
      Overheat Prevention Control History Number of times that assist system was restricted according to the heat generating state due to estimation of the ECU heat-generating spot and motor coil temperature 0 to 255 - -
      Power Supply Voltage Drop Control History Number of times that assist system was stopped due to low power source voltage (9 V or less) 0 to 255 - -
      Power Supply Voltage Drop Restraint Control History Number of times that assist system was restricted due to low power source voltage (9.7 V or less) 0 to 255 - -
      Engine Stall/READY OFF Control History Number of times that assist system was restricted due to an engine stall or shutdown 0 to 255 - -
      High Load Continuous Control Number of Times Number of times that assist system was restricted to prevent the motor from overheating when there was a continuous high load caused by the motor locking due to the contacting of the steering rack end, contacting of the tires with a curb, etc. 0 to 255 - -
      Vehicle Speed Signal Fault Control History Number of times that assist force was fixed to a high vehicle speed assist force when there was a vehicle speed signal malfunction 0 to 255 - -
      Chassis Power Supply Management EPS Control History Chassis power supply management EPS control history 0 to 255 - -
      Load Control History Number of times that electrical load was limited to ensure that power was supplied to the vehicle when the power steering performance could not be ensured while the vehicle was in motion or the battery voltage had dropped to the voltage that might not be able to ensure the performance. 0 to 255 - -

      Chassis > EMPS > Data List 

      Tester Display
      Battery Voltage Drop History
      Engine Revolution Ready Signal Communication Failure History
      Steering Angle Sensor Signal Communication Failure History
      Vehicle Speed Signal Invalid History
      Overheat Prevention Control History
      Power Supply Voltage Drop Control History
      Power Supply Voltage Drop Restraint Control History
      Engine Stall/READY OFF Control History
      High Load Continuous Control Number of Times
      Vehicle Speed Signal Fault Control History
      Chassis Power Supply Management EPS Control History
      Load Control History

      HINT: 

      If the auxiliary battery is not sufficiently charged or the voltage decreases temporarily, the amount of power assist will be reduced and the EPS warning light will come on. In such cases, the amount of power assist returns to normal when the auxiliary battery voltage recovers.

      OK

      No control history

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    NG 

    See step  2

  2. CHECK FOR VEHICLE CONTROL HISTORY (POWER STEERING SYSTEM) 
    1. Check for vehicle control history and note any codes that are output.

      Chassis > EMPS > Utility 

      Tester Display
      Vehicle Control History (RoB)
      1. Record the vehicle control history.

      Result

      Result Proceed to
      Vehicle control history is not output A
      Vehicle control history other than [X206D] are output B
      Vehicle control history [X206D] is output C

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    B 

    GO TO VEHICLE CONTROL HISTORY (RoB). Refer to  VEHICLE CONTROL HISTORY (RoB) [11/2023 - ]  

    Result: 

    C 

    See step  3

  3. CHECK FOR VEHICLE CONTROL HISTORY FREEZE FRAME DATA (POWER STEERING SYSTEM) 
    1. Check for vehicle control history freeze frame data and note any codes that are output.

      Chassis > EMPS > Utility 

      Tester Display
      Vehicle Control History (RoB)
      1. Record the vehicle control history.

      Result

      Result Proceed to
      Vehicle control history is not output A
      Vehicle control history freeze frame data [Status of Vehicle Power (IGP PDC) is OFF] and [Status of Vehicle Power (IGR PDC) is OFF] are output B
      Vehicle control history freeze frame data [Status of Vehicle Power (IGP PDC) is OFF] and [Status of Vehicle Power (IGR PDC) is ON] are output C

    Result: 

    A 

    GO TO CAN COMMUNICATION SYSTEM 

    for HV Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]

    for Gasoline Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]

    Result: 

    B 

    GO TO PROBLEM SYMPTOMS TABLE (ENGINE STALLS) 

    for T24A-FTS: Refer to PROBLEM SYMPTOMS TABLE [10/2022 - ]

    for A25A-FXS, A25B-FXS: Refer to PROBLEM SYMPTOMS TABLE [10/2022 - ]

    Result: 

    C 

    See step  4

  4. CHECK VEHICLE CONTROL HISTORY (AIRBAG SYSTEM) 
    1. Check for vehicle control history freeze frame data and note any codes that are output.

      Body Electrical > SRS Airbag > Utility 

      Tester Display
      Vehicle Control History (RoB)
      RECORD DATA ITEM CHART

      Tester Display Measurement Item Range Diagnostic Note
      Vehicle Speed Vehicle speed at main driven wheels 0 to 200 km/h If the vehicle speed is 200 km/h or more, "200 km/h" is displayed.
      Engine RPM Data Number of crankshaft revolutions in 1 minute 0 to 12800 rpm -
      Shift Position Signal Shift lever position N / D / R / P / 5 / 4 / 3 / 2 / LO / B / SD / S-Mode / Undetermined -
      1. Record the vehicle control history.

        HINT: 

        for HV Model: If the engine is stopped while the vehicle is stationary and the shift position is not P, the EPS warning light (yellow) illuminates and the message "Hybrid System Stopped Steering Power Low" will be displayed on the multi-information display in the combination meter assembly, but this is caused by incorrect operation and is not a malfunction.

        for Gasoline Model: If the engine is stopped while the vehicle is stationary and the shift position is not P, the EPS warning light (yellow) illuminates and the message "Engine Stopped Steering Power Low" will be displayed on the multi-information display in the combination meter assembly, but this is caused by incorrect operation and is not a malfunction.

      Result

      Result Proceed to
      Vehicle control history (vehicle speed 0 km/h or more, engine speed 0 rpm and shift position not in P) is output A
      Vehicle control history (vehicle speed 0 km/h or more, engine speed 0 rpm and shift position not in P) is not output B

    Result: 

    A 

    INCORRECT OPERATION 

    If incorrect operation of the ignition switch causes unintended ignition switch off operation while the shift position is not P, the engine will stop thus causing EPS shutdown and illumination of the EPS warning light (yellow), but this is not a malfunction. (EPS control during engine stall)

    Result: 

    B 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

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