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How To Troubleshoot

WARNING: This page is about a different car, the 2018 Subaru BRZ. However, it is still accessible from the selected car via links, so may be relevant.
  1. Guidelines
    CAUTION:
    • If DTC of CAN communication system is output, always start the troubleshooting according to the procedure described in "How to troubleshoot".
    • When a connector is not fully connected, it may case CAN communication failure. To avoid such failure, make sure to perform contact pressure test. (Refer to SYMPTOM TABLE )
    • Before measuring the resistance of CAN bus, turn the ignition OFF and leave the vehicle as is for at least one minute without operating keys, switches, and doors. Disconnect the battery and wait for another one minute or more.
    • After turning the ignition switch to OFF, you may have to wait for a while before disconnecting the battery terminals. Check appropriate precautions for battery terminal disconnection before proceeding. (Refer to WORKING PRECAUTIONS AND NOTES )
    1. CAN communication error codes are generated due to errors in the main and sub-lines, ECM in the CAN communication system, sensor internal error, and power supply system error. Since both internal and power supply system errors can occur at the same time, make sure to identify the error source properly.
    2. When the data link connector sub-line or Vbus main line seems to be defective, use an electrical tester to check the data link connector terminals.
      CAUTION:
      • In checking the data link connector, use SST (diagnosis check wire No. 2), instead of directly connecting the tester probe to the terminal.
      • The electrical tester cannot support the open circuit check for the sub-line in each ECM and sensor from data link connector.
    3. In case there was a Vbus communication malfunction, identify the ECM and sensor which had lost communication based on the combination of communication error DTCs.
    4. In case an open circuit is detected, check for a loose or unplugged connection by pushing back the connector case before disconnecting connectors for checking.
    5. After disconnecting the connector, make sure that its terminal and the case have no damage, deformation, or corrosion.
  1. Bring in the car
    NOTE:
    • If the ignition can be turned ON, check DTC, illumination status of combination meter waning light, and vehicle operation status immediately. (Example: Air conditioner operation status)
    • Since the failsafe function is partially disabled with IG OFF, do not turn the ignition OFF until the checking is complete.
    • If the ignition cannot be turned ON, measure the battery voltage. If the voltage is less than 11 V, charge or replace the battery and start the troubleshooting.
    • If the battery voltage is normal and the ignition cannot be turned ON, repair defective parts as required before troubleshooting.
  2. Interview and phenomenon check
    NOTE:
    • In order to identify the trouble phenomenon correctly and make an appropriate decision, it is important not to introduce any bias into the troubleshooting process. To understand the circumstances of the failure for proper assessment, the interview with the user plays an important role in the troubleshooting.
    • Ask the user if any add-on accessory (anti-theft system, monitor, and so on) is or was installed. (if installed, inform the user that it needs to be removed to check the trouble phenomenon accurately)
    1. Information about the status and condition of the vehicle at the time of trouble is helpful in identifying the defective parts.
      NOTE:
      • What (system, part, meter warning light)
      • How (details of the defect)
      • When (date and time, frequency, repeatability)
      • Conditions (driving condition, operation condition, weather)
      • Road type (inner city, suburbs, paved road, unpaved road, highway, etc.)
      • Conditions for recovery (how to recover the error. For example, IG OFF)
    CHECK LIST

    Phenomenon  
    • Electric power steering effort is:
      • Normal
      • A bit heavy
      • Assist is not working
    • Air Conditioner
      • Was the air conditioner working?
      • Blower fan is working or not
    • Multi information display:
      • Each display is updated or not
    • Smart function:
      • Does lock or unlock occur?
      • Does the illumination come on within the smart detection area?
    • Other findings related to system operation
    Meter warning light  
    • Warning light status, illuminating order
      • Slip indicator light ON
      • ABS warning light ON
      • Check engine warning light ON
      • Brake warning light ON
      • Airbag warning light ON
      • Others
    • Meter display
      • Shift indicator
      • Speedmeter
      • Tachometer (0 r/min fixed?)
      • Engine coolant temperature gauge (fixed to COLD lower limit?)
  3. Basic inspection (CAN diagnostic is not used)
    1. Check components which may cause CAN communication error. (Refer to BASIC INSPECTION )

    NG: Repair or replace each component.

    OK: Go to next step

  4. Checking of communication for initializing.
    1. Communicate with the all systems by connecting SSM4.

      Criteria: The communication for initializing is successful for each system. (NG if the communication for initializing is not successful for any of the systems)

    NG: Perform the inspection using "Check sheet of communication for initializing". (Refer to BASIC INSPECTION )

    OK: Go to next step

  5. Basic inspection (CAN diagnostic is used)
    1. Check components which may cause CAN communication error. (Refer to BASIC INSPECTION )

    NG: Repair or replace each component.

    OK: Go to next step

  6. DTC check
    1. Start the engine and read all DTCs.
      NOTE: When the engine does not start, perform the diagnosis for the engine start malfunction.
    2. Record all DTCs and freeze frame data.
    Result Go to
    DTC U**** is displayed A
    DTC U**** is not displayed B

    B: Go to Step 8

    A: Go to next step

  7. DTC check
    1. Perform the inspection using DTC check sheet.
    2. Use SSM4 to read all DTCs.
    Result Go to
    DTC U**** is displayed B
    DTC U**** is not displayed A

    B: Go to Step 9

    A: Go to next step

  8. General diagnostics
    1. Inspect using the "General Diagnostics Table". (Refer to GENERAL DIAGNOSTIC TABLE )

    OK: LAN system is normal

    NG: LAN system is normal

  9. Implementation of diagnosis
    1. Repair the trouble cause.
    2. Perform the clear memory mode.
    3. Read the DTC.
    Result Go to
    DTC is displayed B
    DTC is not displayed A

    B: Repeat Step 9 until DTC is not shown.

    A: Go to next step

    Complete

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