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

B003Y5EE05

CAUTION / NOTICE / HINT

Note

If the power steering ECU assembly has been replaced, perform assist map writing, rotation angle sensor initialization and torque sensor zero point calibration.

Click here

Tech Tips

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR


    1. Jiggle the power steering ECU assembly connectors and wire harness up and down, and left and right to check the illumination condition of the EPS warning light in the combination meter assembly.

      OK
      The EPS warning light illumination condition does not change.

      Tech Tips

      When the EPS warning light is operating properly, it comes on when the power switch is turned on (IG) and goes off when the power switch is turn on (READY).

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK CAN COMMUNICATION SYSTEM


    1. Check for DTCs.

      Click here

      Result
      Result Proceed to
      CAN communication system DTCs are not output. A
      CAN communication system DTCs are output. B

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    A

  3. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - GROUND)


    1. Disconnect the A19 power steering ECU assembly connector.

    2. B003XR2C27
      *a

      Front view of wire harness connector

      (to Power Steering ECU Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A19-14 (IG) - Body ground Power switch on (IG) 8 to 16 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A19-9 (PGND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT EPS RELAY (ELECTRIC POWER STEERING RELAY)


    1. Remove the EPS relay (electric power steering relay) from the No. 1 engine room relay block and No. 1 junction block assembly.

    2. B003Y4ZC02
      *a EPS Relay (Electric Power Steering Relay)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      5 - 3 Voltage not applied between terminals 1 and 2 10 kΩ or higher
      5 - 3 Voltage applied between terminals 1 and 2 Below 1 Ω
      1 - 3 Voltage not applied between terminals 1 and 2 10 kΩ or higher
      2 - 5 Voltage not applied between terminals 1 and 2 10 kΩ or higher
      1 - 2 Voltage not applied between terminals 1 and 2 180 to 220 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE EPS RELAY (ELECTRIC POWER STEERING RELAY)

    OK

  5. CHECK HARNESS AND CONNECTOR (AUXILIARY BATTERY - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY)


    1. B003XWLC01
      *a

      Component without EPS relay (electric power steering relay) connected

      (No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly)
      *b

      Component without EPS relay (electric power steering relay) connected

      (EPS Relay (electric power steering relay) connection area)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 - Body ground Always 9 to 16 V
      5 - Body ground Always 9 to 16 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY - POWER STEERING ECU ASSEMBLY)


    1. Disconnect the A19 power steering ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A19-10 (PIG) - 3 (No. 1 engine room relay block and No. 1 junction block assembly) Always Below 1 Ω
      A19-12 (RLY) - 2 (No. 1 engine room relay block and No. 1 junction block assembly) Always Below 1 Ω
      A19-10 (PIG) or 3 (No. 1 engine room relay block and No. 1 junction block assembly) - Body ground Always 10 kΩ or higher
      A19-12 (RLY) or 2 (No. 1 engine room relay block and No. 1 junction block assembly) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT COMBINATION METER ASSEMBLY


    1. Reconnect the A19 power steering ECU assembly connector.

    2. Perform the Active Test of the combination meter assembly using the GTS.


      Body Electrical > Combination Meter > Active Test
      Tester Display
      Indicat. EPS

    3. Check the combination meter assembly.

      OK
      The EPS warning light turns on or off in accordance with the GTS operation.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE POWER STEERING ECU ASSEMBLY for LHD: Click here
    REPLACE POWER STEERING ECU ASSEMBLY for RHD: Click here

    NG

    GO TO METER / GAUGE SYSTEM Click here