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Home >> Subaru >> 2020 >> Outback Base >> Repair and Diagnosis >> Steering >> Steering Control Systems >> Power Steering System (Diagnostics) >> Warning Light Illumination Pattern >> Steering Warning Light Does Not Come On >> Power Steering Assist Disabled

Power Steering Assist Disabled

Detecting condition: 

CAN communication error (engine rpm signal not received)

Trouble symptom: 

NOTE:
  • During driving, the assist system will not be activated when the ignition voltage drops.
  • Power steering assist is not started unless both of the ignition switch ON signal and the engine speed signal are input.
  • In any of the following cases, the power steering assist is limited and steering wheel operation may become heavy.

    If the steering wheel is held to an end for a long time, or the steering wheel turning to right and left at slow speed is repeated during parking, the assist limitation (overheat protection control) may operate to prevent failures by overheat.

    In this case, by stopping the engine for approx. 30 minutes for cooling, the assist will start operating. While assist limitation (overheat protection control) is in active, [Limited Assist] is displayed in [EPS Status] in the Subaru Select Monitor [Data Monitor].

  • History can be confirmed on [ECU Overheat Protection] or [IGN count from overheating protection (most recent)] of [Data Monitor].
  • The overheat protection control system is normal operation, therefore, the STEERING warning light will not come on and there will be no DTC displayed.
  • If the power steering system connector is disconnected while cooling under the overheat protection control, different DTC may be recorded. If there is no DTC and assist limitation is in active, stop the engine for approx. 10 minutes for cooling.
  1. CHECK BATTERY  .

    Check the battery. Refer to STARTING/CHARGING SYSTEMS (H4DO)>BATTERY>INSPECTION . Refer to STARTING/CHARGING SYSTEMS (H4DOTC)>Battery>INSPECTION .

    Is the check result OK?

    Yes  : Go to  2.

    No  : Charge or replace the battery.

  2. CHECK BATTERY TERMINAL AND FUSE  .

    Check the battery terminals and the fuse.

    Is the check result OK?

    Yes  : Go to  3.

    No  : Repair or replace faulty parts.

  3. CHECK DTC  .

    Read the DTC of [Brake Control] using the Subaru Select Monitor. Refer to BRAKE CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC related to VDC system or ignition power supply system displayed?

    Yes  : Perform the diagnosis according to the DTC. Refer to BRAKE CONTROL (DIAGNOSTICS)>Diagnostic Trouble Code (DTC)>LIST .

    No  : Go to  4.

  4. CHECK DATA MONITOR  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read data of [Engine Speed] in the [Data Monitor] of [Power Steering]. Refer to POWER STEERING (DIAGNOSTICS)>Data Monitor .

      Is [Engine Speed] the same as that in the combination meter?

      Yes  : Go to  5.

      No  : Check the CAN communication. Refer to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

  5. CHECK DATA MONITOR  .

    Using the Subaru Select Monitor, read data of [EPS Status] in the [Data Monitor] of [Power Steering]. Refer to POWER STEERING (DIAGNOSTICS)>Data Monitor .

    Is [Assist limitation] displayed?

    Yes  : It is possible that temporary assist limitation has occurred due to overheat protection. Stop the engine for approx. 30 minutes, and check again.

    No  : Go to  6.

  6. CHECK DATA MONITOR  .
    1. Using the Subaru Select Monitor, read data of [Torque sensor main output], [Torque sensor sub output] in the [Data Monitor] of [Power Steering]. Refer to POWER STEERING (DIAGNOSTICS)>Data Monitor .
    2. Move the steering wheel to the left and right.

      Do the values of [Torque sensor main output] and [Torque sensor sub output] change along with the operation?

      Yes  : Go to  7.

      No  : Check for poor contact of the torque sensor connector.

  7. CHECK DATA MONITOR  .

    Using the Subaru Select Monitor, read data of [IG voltage] in the [Data Monitor] of [Power Steering]. Refer to POWER STEERING (DIAGNOSTICS)>Data Monitor .

    Is [IG voltage] stable? (While wiggling the harness)

    Yes  : Go to  8.

    No  : Check the ignition switch and IG voltage harness, and repair the defective part.

  8. CHECK CONNECTOR  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector (B53).

      Are there any damages to terminal or other parts either on the power steering control module side or on the connector side?

      Yes  : Repair the terminal.

      No  : Replace the steering gearbox. Refer to POWER ASSISTED SYSTEM (POWER STEERING)>Electric Power Steering Gearbox .

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