POWER STEERING SYSTEM PS Warning Light Remains ON

DESCRIPTION

If the power steering ECU detects a malfunction, the EPS warning light comes on. At this time, the power steering ECU stores a DTC in its memory.

WIRING DIAGRAM

A004NYKE02

CAUTION / NOTICE / HINT

Note


  • If the power steering ECU assembly is replaced with a new one, perform rotation angle sensor initialization and torque sensor zero point calibration Click here.

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

When the power supply voltage to the power steering ECU (terminals IG and PIG) drops, required steering effort increases and the EPS warning light turns on.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR


    1. Turn the ignition switch to ON.

    2. Check the indication condition of the EPS warning light by wiggling the power steering ECU connector and wire harness up and down, and right and left.

      OK
      EPS warning light indication condition does not change.

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK FOR DTC (CAN COMMUNICATION SYSTEM)


    1. Check for DTCs Click here.

      OK
      DTC is not output.

    NG

    GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) Click here

    OK

  3. READ VALUE USING INTELLIGENT TESTER (IG POWER SUPPLY)


    1. Turn the ignition switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the intelligent tester on.

    5. Enter the following menus: Chassis / EMPS / Data List.

      EMPS
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      IG Power Supply

      ECU power source voltage/

      Min.: 0.0000 V

      Max.: 20.1531 V

      		 11 to 14 V The ignition switch is ON.
      OK
      The normal condition value is displayed the intelligent tester.

    NG

    CHECK HARNESS AND CONNECTOR (POWER STEERING ECU - BODY GROUND) Click here

    OK

  4. READ VALUE USING INTELLIGENT TESTER (PIG POWER SUPPLY)


    1. Turn the ignition switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Start the engine.

    4. Turn the intelligent tester on.

    5. Enter the following menus: Chassis / EMPS / Data List.

      EMPS
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      PIG Power Supply

      Power source voltage to active motor/

      Min.: 0.0000 V

      Max.: 20.1531 V

      		 11 to 14 V The engine is running and power steering is operating.
      OK
      The normal condition value is displayed the intelligent tester.

    NG

    CHECK HARNESS AND CONNECTOR (POWER STEERING ECU - BATTERY/BODY GROUND) Click here

    OK

  5. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (METER / GAUGE SYSTEM)


    1. Perform the Active Test of the combination meter using the intelligent tester Click here.

      Combination Meter
      Tester Display Test Part Control Range Diagnostic Note
      Indicat. EPS EPS warning light ON or OFF Perform the test with the vehicle stopped and the engine idling.

    2. Check that the EPS warning light operates in accordance with the Active Test.

      Tech Tips

      Reconnect the connectors and restore the vehicle to its previous condition before checking the combination meter.

      Result
      Result Proceed to
      OK for LHD A
      for RHD B
      NG C

    A

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    B

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    C

    REPLACE COMBINATION METER ASSEMBLY Click here

  6. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU - BODY GROUND)


    1. A004TJJE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Power Steering ECU)

      Disconnect the A29 power steering ECU connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A29-2 (PGND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY)


    1. A004RY5E02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Power Steering ECU)

      Disconnect the D50 power steering ECU connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D50-6 (IG) - Body ground Ignition switch ON 11 to 14 V
      Result
      Result Proceed to
      OK for LHD A
      for RHD B
      NG C

    A

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    B

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    C

    GO TO STOP AND START SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) Click here

  8. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU - BATTERY/BODY GROUND)


    1. A004PRSE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Power Steering ECU)

      Disconnect the A29 power steering ECU connector .

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A29-1 (PIG) - Body ground Always 11 to 14 V

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A29-2 (PGND) - Body ground Always Below 1 Ω
      Result
      Result Proceed to
      OK for LHD A
      for RHD B
      NG C

    A

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    B

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR