2008 Lexus IS FFACTORY OEM SERVICE PROCEDURE

Power Steering System: Precaution

NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system after the cable is reconnected.
POWER STEERING SYSTEM CHART

System Name See Procedure
Power Window Control System INITIALIZATION
  1. HANDLING PRECAUTIONS FOR SRS AIRBAG SYSTEM 
    1. The vehicle is equipped with an SRS (Supplemental Restraint System). 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 (See PRECAUTION )

  2. PRECAUTIONS FOR REMOVAL, INSTALLATION AND REPLACEMENT OF ELECTRONIC MOTOR POWER STEERING COMPONENTS 
    1. Be sure to align the front wheels straight ahead when removing and installing the power steering gear assembly
    2. When disconnecting the steering sliding yoke sub-assembly and the pinion shaft of the power steering gear assembly, be sure to place matchmarks before servicing
    3. After replacing the steering column assembly or power steering ECU assembly, calibrate the torque sensor zero point (See CALIBRATION )
  3. HANDLING PRECAUTIONS 
    1. When handling the electronic parts
      1. Avoid any impact to electronic parts such as ECUs and relays. Replace these parts with new ones if dropped or subjected to a severe blow
      2. Do not expose any electronic parts to high temperature or humidity.
      3. Do not touch the connector terminals in order to prevent deformation or malfunctions due to static electricity
      4. If the power steering ECU assembly has been replaced with a new one, initialize the rotation angle sensor value and calibrate the torque sensor zero point (See CALIBRATION )
    2. When handling the power steering gear assembly
      1. Avoid any impact to the power steering gear assembly, especially to the motor or torque sensor Replace these parts with new ones if dropped or subjected to a severe blow
      2. Do not pull on the wire harness when moving the power steering gear assembly.
      3. If the power steering gear assembly has been replaced with a new one, clear the rotation angle sensor calibration value, initialize the rotation angle sensor value, and calibrate the torque sensor zero point (See CALIBRATION ).
    3. When disconnecting and reconnecting the connectors
      1. Turn the engine switch on (IG), center the steering wheel, and turn the engine switch off again before disconnecting the connectors related to the electronic power steering system
      2. Ensure that the engine switch is off before reconnecting the connectors related to the power steering system After reconnecting, center the steering wheel and turn the engine switch on (IG)
        NOTE: Do not turn the engine 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 right and left If there is a difference in steering effort between right and left, perform steering zero point calibration (See CALIBRATION )
  4. PRECAUTIONS FOR CAN COMMUNICATION 
    1. CAN communication is used to receive information from the skid control ECU, power steering ECU assembly, ECM, and steering angle sensor as well as to transmit warnings to the combination meter It is also used for communication between terminals TC and TS of the DLC3 If there are any problems in the CAN communication lines, DTCs indicating communication line malfunctions are output
    2. Perform troubleshooting for communication line problems if CAN communication DTCs are output Be sure to start troubleshooting on the electric power steering system only when data communication is normal
    3. Temporary fixing or repair with bypass wiring, etc is impossible because the length and path of each CAN communication line is specified
  5. BUS LINE REPAIR 
    1. After repairing the bus line with solder, wrap the repaired part with electrical tape
      NOTE:
      • The CANL bus line and CANH bus line must be installed together all the times.

        When installing, make sure to braid them. CAN bus lines are likely to be influenced by electrical noise if they are not braided.

      • The difference in length between the CANL bus line and CANH bus line should be 100 mm (3.937 in.) or less.
      • Leave approximately 80 mm (3.150 in.) loose in the braided wires around the connector.
Factory Service Tools

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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.