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HOMESERVICE MANUALSTOYOTA2010YARIS 4D SEDAN, STANDARDREPAIR AND DIAGNOSISSTEERINGMANUAL STEERINGPOWER STEERING (DIAGNOSTIC CODES & CIRCUIT TESTS)POWER STEERING SYSTEMCIRCUIT TESTEPS WARNING LIGHT CIRCUITPROCEDURE
2010 Toyota Yaris 4D Sedan, Standard

EPS Warning Light Circuit: Procedure

2010 Toyota Yaris 4D Sedan, StandardSECTION Procedure
  1. INSPECT CAN COMMUNICATION SYSTEM 
    1. Using a Techstream, check for DTCs and confirm that there are no problems in the CAN communication system.

      OK

      DTCs are not output.

    NG → GO TO  CAN COMMUNICATION SYSTEM 

    OK: Go to next step 

  2. READ VALUE USING TECHSTREAM 
    1. Connect a Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Chassis / EMPS / Data List.
    5. Select the item "IG Power Supply" in the Data List and read the value displayed on the Techstream.
      EMPS:

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      IG Power Supply ECU power source voltage: Minimum: 0.0000 V, Maximum: 20.1531 V 11 to 14 V: Ignition switch ON -

      OK

      The normal condition value is displayed on the Techstream.

      HINT: 

      If the voltage is not standard value, inspect the IG power source circuit.

    NG → See step   6 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU - BODY GROUND) 
    Fig 1: Identifying A19 And D31 Power Steering ECU Connectors
    GTY247688Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the connectors from the power steering ECU.
    2. Measure the voltage and the resistance.

      Standard

      Tester Connection Condition Specified Condition
      IG (D31-6) - Body ground Ignition switch on 11 to 14 V
      PGND (A19-2) - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. REPLACE POWER STEERING ECU 
    NOTE:

    After replacing the power steering ECU, perform the torque sensor zero point calibration.

    NEXT: Go to next step 

  5. CHECK PS WARNING LIGHT (COMBINATION METER) 
    1. Check that the P/S warning light on the combination meter does not come on.

      OK

      The P/S warning light does not come on.

    NG → REPLACE COMBINATION METER 

    OK → END 

  6. INSPECT POWER SOURCE CIRCUIT (IG) See step   1 
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.