2012 Toyota Prius ThreeFACTORY OEM SERVICE PROCEDURE

Power Steering System: Precaution: Precaution

WARNING: This page is about a different variant/trim than selected.
  1. PRECAUTION FOR DISCONNECTING THE AUXILIARY BATTERY CABLE 
    NOTE:

    When disconnecting the auxiliary battery negative (-) cable, initialize the following system after the cable is reconnected:

    System See Procedure
    Power Door Lock Control System Refer to CALIBRATION 
  2. HANDLING PRECAUTIONS FOR SRS AIRBAG SYSTEM 
    1. This vehicle is equipped with a Supplemental Restraint System (SRS). Failure to carry out service operations in the correct sequence could cause the SRS to unexpectedly deploy during servicing. This may cause a serious accident.

      Before servicing (including inspection, replacement, removal and installation of parts), be sure to read the precautionary notices for the Supplemental Restraint System. Refer to PRECAUTION .

  3. PRECAUTIONS FOR REMOVAL, INSTALLATION AND REPLACEMENT OF ELECTRONIC POWER STEERING COMPONENTS 
    1. Be sure to align the front wheels straight ahead when removing and installing the steering gear assembly.
    2. When disconnecting the steering intermediate shaft assembly, be sure to place matchmarks before starting the operation.
    3. After replacing the steering post assembly or power steering ECU assembly, calibrate the torque sensor zero point. Refer to CALIBRATION .
  4. HANDLING PRECAUTION 
    1. When handling electronic parts:
      1. Avoid any impact to parts such as ECUs and relays. Replace them with new ones if dropped or subjected to a severe blow.
      2. Do not expose any electronic parts to high temperatures or humidity.
      3. In order to prevent deformation or malfunctions due to static electricity, do not touch the connector terminals.
    2. When handling the power steering ECU assembly:
      1. When the power steering ECU assembly has been replaced with a new one, perform assist map writing and torque sensor zero point calibration. Refer to CALIBRATION .
    3. When handling the steering post assembly:
      1. Avoid any impact to the steering post assembly, especially to the motor and torque sensor. Replace them with new ones if dropped or subjected to a severe blow.
      2. Do not pull the wire harness when moving the steering post assembly.
      3. When the steering post assembly has been replaced, perform torque sensor zero point calibration after initializing the torque sensor zero point. Refer to CALIBRATION .
    4. When disconnecting and reconnecting the connectors:
      1. Before disconnecting the connectors related to the power steering system, turn the power switch on (IG), center the steering wheel, turn the power switch off, and then disconnect the connectors.
      2. Before reconnecting the connectors related to the power steering system, ensure that the power switch is off. Then center the steering wheel and turn the power switch on (IG).
        NOTE:

        Do not turn the power switch on (IG) when the steering wheel is not centered.

      3. If the above operations are not carried out properly, the steering center point (zero point) will deviate, which may lead to a difference in steering effort between turning right and left. If there is a difference in steering effort between turning right and left, perform torque sensor zero point calibration after initializing the torque sensor zero point. Refer to CALIBRATION .
  5. PRECAUTIONS FOR CAN COMMUNICATION 
    1. CAN communication lines are used to receive information from the skid control ECU and ECM, and to transmit warnings to the combination meter assembly. When problems are detected in the CAN communication lines, CAN communication DTCs are stored.
    2. Perform troubleshooting for communication problems when CAN communication DTCs are output. Be sure to start troubleshooting the electronic power steering system after confirming that the CAN communication system is normal.
    3. Since the CAN communication lines each have their own length and route, they cannot be temporarily repaired with a bypass wire, etc.
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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.

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