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Home >> Toyota >> 2023 >> GR86 Base, Automatic Trans >> Repair and Diagnosis (Single Page) >> Electrical >> Body Electrical >> Body Control System - Diagnostic Codes >> Body Control System >> DTC U1674: LIN Communication Bus 2 Error Body Control Module [11/2021 - ] >> Procedure
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DTC U1674: LIN Communication Bus 2 Error Body Control Module [11/2021 - ]: Procedure

  1. CHECK DTC 
    1. Turn the ignition switch to OFF.
    2. Turn the ignition switch to ON.
    3. Wait for 10 seconds.
    4. Read the DTC of [Body Control] using the GTS.

      Body Electrical > Body Control > Trouble Codes 

      Is DTC U1674 displayed? (Current code)

      Result Proceed to
      Yes A
      No (Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.)
      HINT: 
      In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.      		 B

    Result: 

    B 

    USE SIMULATION METHOD TO CHECK 

    Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ]

    Result: 

    A 

    See step  2

  2. CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) CUSTOMIZATION 
    1. Using GTS, make sure the [Customize] setting values of [Body Control] correspond to the vehicle.

      Refer to CUSTOMIZE PARAMETERS [11/2021 - 10/2024] , or refer to CUSTOMIZE PARAMETERS [10/2024 - ]

      Is the setting value of [P/W ECU Setting] equal to [Driver/Passenger Seat]?

      Result Proceed to
      Yes A
      No (Change the setting value to [Driver/Passenger Seat].) B

    Result: 

    B 

    CHANGE THE SETTING VALUE TO [DRIVER/PASSENGER SEAT] 

    Refer to CUSTOMIZE PARAMETERS [11/2021 - 10/2024] , or refer to CUSTOMIZE PARAMETERS [10/2024 - ]

    Result: 

    A 

    See step  3

  3. CHECK CONTROL MODULE 
    1. Turn the ignition switch to OFF.
    2. Disconnect the power window regulator master switch assembly connector.
    3. Turn the ignition switch to ON.
    4. Wait for 10 seconds.
    5. Read the DTC of [Body Control] using the GTS.

      Body Electrical > Body Control > Trouble Codes 

      Is DTC U1674 displayed? (Current code)

      Result Proceed to
      Yes A
      No (Replace the power window regulator master switch assembly.) B

    Result: 

    B 

    REPLACE POWER WINDOW REGULATOR MASTER SWITCH ASSEMBLY 

    Refer to REMOVAL [11/2021 - ]

    Result: 

    A 

    See step  4

  4. CHECK CONTROL MODULE 
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from the power window regulator motor assembly (driver's side). (With the power window regulator master switch assembly connector disconnected)
    3. Turn the ignition switch to ON.
    4. Wait for 10 seconds.
    5. Read the DTC of [Body Control] using the GTS.

      Body Electrical > Body Control > Trouble Codes 

      Is DTC U1674 displayed? (Current code)

      Result Proceed to
      Yes A
      No (Replace the power window regulator motor assembly (driver's side).) B

    Result: 

    B 

    REPLACE POWER WINDOW REGULATOR MOTOR ASSEMBLY (DRIVER'S SIDE). 

    Refer to REMOVAL [11/2021 - ]

    Result: 

    A 

    See step  5

  5. CHECK CONTROL MODULE 
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from the power window regulator motor assembly (passenger's side). (With the power window main switch connector and the power window regulator motor assembly (driver's side) connector disconnected)
    3. Turn the ignition switch to ON.
    4. Wait for 10 seconds.
    5. Read the DTC of [Body Control] using the GTS.

      Body Electrical > Body Control > Trouble Codes 

      Is DTC U1674 displayed? (Current code)

      Result Proceed to
      Yes A
      No (Replace the power window regulator motor assembly (passenger's side).) B

    Result: 

    B 

    REPLACE POWER WINDOW REGULATOR MOTOR ASSEMBLY (PASSENGER'S SIDE). 

    Refer to REMOVAL [11/2021 - ]

    Result: 

    A 

    See step  6

  6. CHECK HARNESS (OPEN CIRCUIT) 
    1. Turn the ignition switch to OFF.
    2. Disconnect the main body ECU (multiplex network body ECU) connector.
    3. Using a tester, measure the resistance between the main body ECU (multiplex network body ECU) connector and each unit connector.

      Connector & terminal

      F58-4 (P/W_LIN) - J2-17

      F58-4 (P/W_LIN) - H5-7

      F58-4 (P/W_LIN) - J4-7

      Is the resistance less than 10 Ω?

      Result Proceed to
      Yes A
      No (Repair the open circuit of harness.) B

    Result: 

    B 

    REPAIR THE OPEN CIRCUIT OF HARNESS 

    Result: 

    A 

    See step  7

  7. CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY) 
    1. Turn the ignition switch to ON.
    2. Using a tester, measure the voltage between each unit connector and the chassis ground.

      Connector & terminal

      F58-4 (P/W_LIN) (+) - Chassis ground (-)

      J2-17 (+) - Chassis ground (-)

      H5-7 (+) - Chassis ground (-)

      J4-7 (+) - Chassis ground (-)

      Is the voltage less than 1 V?

      Result Proceed to
      Yes A
      No (Repair the short circuit to power supply in harness.) B

    Result: 

    B 

    REPAIR THE SHORT CIRCUIT TO POWER SUPPLY IN HARNESS 

    Result: 

    A 

    See step  8

  8. CHECK HARNESS (GROUND SHORT CIRCUIT) 
    1. Turn the ignition switch to OFF.
    2. Using a tester, measure the resistance between each unit connector and the chassis ground.

      Connector & terminal

      F58-4 (P/W_LIN) - Chassis ground

      J2-17 - Chassis ground

      H5-7 - Chassis ground

      J4-7 - Chassis ground

      Is the resistance 1 MΩ or more?

      Result Proceed to
      Yes (Replace the main body ECU (multiplex network body ECU).) A
      No (Repair the ground short circuit of harness.) B

    Result: 

    A 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 

    Refer to REMOVAL [11/2021 - ]

    Result: 

    B 

    REPAIR THE GROUND SHORT CIRCUIT OF HARNESS 

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