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Home >> Subaru >> 2020 >> BRZ tS >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Automatic Transaxle (Diagnostics)) >> Automatic Transmission System >> DTC P0979: Shift Solenoid "C" Control Circuit Low; DTC P0980: Shift Solenoid "C" Control Circuit High >> Inspection steps

Inspection steps

WARNING: This page is about a different variant/trim than selected.
NOTE: ON/OFF status when transmission 3 way solenoid ASSY (S3) is normal (Select lever in D position)
Gear position 1st 2nd 3rd 4th 5th 6th
Transmission 3 way solenoid ASSY (S3) ON ON ON OFF OFF OFF
  1. Check of transmission 3 way solenoid ASSY (S3) system
    1. Disconnect the connector A18 of the transmission control computer ASSY.
    2. Measure the voltage between the terminals. (Refer to ECM TERMINAL ARRANGEMENT  for terminal arrangement of transmission control computer ASSY)
      VOLTAGE SPECIFICATION

      Inspection terminals Inspection conditions Standard value
      A18-6 (S3) - chassis ground IG ON Less than 1 V
    3. Measure the resistance between the terminals. (Refer to ECM TERMINAL ARRANGEMENT  for terminal arrangement of transmission control computer ASSY)
      STANDARD VALUE RESISTANCE SPECIFICATION

      Inspection terminals Inspection conditions Standard value
      A18-6 (S3) - chassis ground 20°C 11 to 15Ω
    4. Connect the connector A18 of the transmission control computer ASSY.

    NG: Go to Step  4.

    OK: Go to next step

  2. Check wiring harness and connector (transmission wire - transmission control computer)
    1. Disconnect the connector A18 of the transmission control computer ASSY.
    2. Disconnect the connector L4 of the transmission wire.
    3. Measure the voltage between the terminals.
      VOLTAGE SPECIFICATION

      Inspection terminals Inspection conditions Standard value
      L4-7 (S3) - chassis ground IG ON Less than 1 V
    4. Measure the resistance between the terminals.
      STANDARD VALUE RESISTANCE SPECIFICATION

      Inspection terminals Inspection conditions Standard value
      L4-7 (S3) - A18-6 (S3) Always Less than 1 Ω
      L4-7 (S3) - chassis ground Always 10 k Ω or more
    5. Connect the connector L4 of the transmission wire.
    6. Connect the connector A18 of the transmission control computer ASSY.

    NG: Repair or replacement of wiring harness or connector

    OK: Go to next step

  3. Replacement of transmission control computer ASSY
    1. Replace the transmission control computer ASSY. (Refer to TRANSMISSION CONTROL COMPUTER ASSY )

    AT unit correction (refer to WORK SUPPORT  )

  4. Check of transmission 3 way solenoid ASSY (S3) unit
    1. Remove the transmission 3 way solenoid ASSY (S3). (Refer to DISASSEMBLY )
    2. Check the transmission 3 way solenoid ASSY (S3) unit. (Refer to NEUTRAL START SWITCH ASSY )

    NG: Replacement of the transmission 3 way solenoid ASSY (S3) (Refer to ASSEMBLY )

    OK: Go to next step

    Repair or replacement of transmission wire (refer to TRANSMISSION WIRE )

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