POWER STEERING SYSTEM EPS Warning Light Circuit

DESCRIPTION

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

WIRING DIAGRAM

A004IDAE14

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 assembly (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 assembly 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 GTS (IG POWER SUPPLY)


    1. Turn the ignition switch off.

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the GTS 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

      		 9 to 16 V The ignition switch is ON.
      OK
      The normal condition value is displayed the GTS.

    NG

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

    OK

  4. READ VALUE USING GTS (PIG POWER SUPPLY)


    1. Turn the ignition switch off.

    2. Connect the GTS to the DLC3.

    3. Start the engine.

    4. Turn the GTS 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

      		 9 to 16 V The engine is running and power steering is operating.
      OK
      The normal condition value is displayed the GTS.

    NG

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

    OK

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


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

      Combination Meter
      Tester Display Test Part Control Range Diagnostic Note
      Indicat. EPS EPS warning light OFF/ON Vehicle is stopped and engine is 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.


    OK

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    NG

    REPLACE COMBINATION METER ASSEMBLY Click here

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


    1. A004J98E04
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Power Steering ECU Assembly)

      Disconnect the A14 and A15 power steering ECU assembly connectors.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A15-6 (IG) - Body ground Ignition switch ON 9 to 16 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A14-2 (PGND) - Body ground Always Below 1 Ω

    OK

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. A004IQYE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Power Steering ECU Assembly)

      Disconnect the A14 power steering ECU assembly connector .

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A14-1 (PIG) - Body ground Always 9 to 16 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A14-2 (PGND) - Body ground Always Below 1 Ω

    OK

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR