REAR POWER SEAT CONTROL SYSTEM, Diagnostic DTC:B2656

DTC Code DTC Name
B2656 Upper Lumbar Adjustment Sensor Malfunction

DESCRIPTION

When the position control ECU does not receive a sensor signal despite forward or backward movement of the seat by power seat motor operation, this DTC is output.

DTC Code DTC Detection Condition Trouble Area
B2656 Sensor's forward and backward lock detection position is the same

  • Position control ECU

  • Rear seatback assembly

  • Harness or connector

WIRING DIAGRAM

A000YA7E18

PROCEDURE


  1. CHECK FOR DTC


    1. DTC output area check


      1. Using the intelligent tester, determine the area that output the DTC.

        Result
        Result Proceed to
        B2656 output from rear left seat ECU A
        B2656 output from rear right seat ECU B

    B

    PERFORM ACTIVE TEST USING INTELLIGENT TESTER (POWER SEAT MOTOR FUNCTION) Click here

    A

  2. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (POWER SEAT MOTOR FUNCTION)


    1. Select the Active Test, use the intelligent tester to generate a control command, and then check the power seat motor function.

      Rear Left Seat
      Tester Display Test Part Control Range Diagnostic Note
      Rear Seat Lumbar Adjustment Seat lumbar operation Front / OFF / Rear -
      OK
      Motor operates normally.

    NG

    INSPECT REAR SEATBACK ASSEMBLY LH (POWER SEAT MOTOR) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU LH - REAR POWER SEAT MOTOR LH)


    1. A000Y77E02
      *1 Front view of wire harness connector: (to Position Control ECU LH)
      *2 SSMR
      *3 Front view of wire harness connector: (to Rear Power Seat Motor LH)

      Disconnect the f43 ECU connector.

    2. Disconnect the f45 motor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      f43-17 (PVCC) - f45-5 (PVCC) Always Below 1 Ω
      f43-7 (SSMR) - f45-2 (SSMR) Always Below 1 Ω
      f43-23 (SGND) - f45-6 (GND) Always Below 1 Ω
      f43-17 (PVCC) - Body ground Always 10 kΩ or higher
      f43-7 (SSMR) - Body ground Always 10 kΩ or higher
      f43-23 (SGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK REAR SEATBACK ASSEMBLY LH (POSITION CONTROL SENSOR)


    1. A000W0SE01
      *1 Front view of wire harness connector: (to Rear Power Seat Motor LH)

      Disconnect the f45 motor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      f45-5 (PVCC) - f45-6 (GND) Upper lumbar switch ON 7.2 to 8.8 V
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    B

    REPLACE POSITION CONTROL ECU LH Click here

    C

    REPLACE POSITION CONTROL ECU LH Click here

    A

  5. CHECK REAR SEATBACK ASSEMBLY LH (POSITION CONTROL SENSOR)


    1. A000V2DE02
      *1 Component with harness connected: (Rear Power Seat Motor LH)
      *2 SSMR

      Reconnect the f45 motor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      f45-2 (SSMR) - Body ground Upper lumbar switch ON 0 to 8 V
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    B

    REPLACE REAR SEATBACK ASSEMBLY LH Click here

    C

    REPLACE REAR SEATBACK ASSEMBLY LH Click here

    A

  6. CHECK FOR DTC


    1. Clear the DTC Click here.

    2. Recheck for DTC.

      OK
      DTC B2656 is not output.
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE POSITION CONTROL ECU LH Click here

    C

    REPLACE POSITION CONTROL ECU LH Click here

  7. INSPECT REAR SEATBACK ASSEMBLY LH (POWER SEAT MOTOR)


    1. A000XLWE02
      *1 Component without harness connected: (Rear Power Seat Motor LH)

      Check operation of the power seat motor (upper lumbar motor).


      1. Check if the seatback moves smoothly when the battery is connected to the upper lumbar motor connector terminals.

        OK
        Measurement Condition Operational Direction

        Battery positive (+) → 4

        Battery negative (-) → 3

        		 Forward

        Battery positive (+) → 3

        Battery negative (-) → 4

        		 Backward
        Result
        Result Proceed to
        OK A
        NG (except Ottoman) B
        NG (for Ottoman) C

    B

    REPLACE REAR SEATBACK ASSEMBLY LH Click here

    C

    REPLACE REAR SEATBACK ASSEMBLY LH Click here

    A

  8. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU LH - REAR POWER SEAT MOTOR LH)


    1. A000X8NE03
      *1 Front view of wire harness connector: (to Position Control ECU LH)
      *2 Front view of wire harness connector: (to Rear Power Seat Motor LH)
      *3 RNBL
      *4 RNFL

      Disconnect the f24 ECU connector.

    2. Disconnect the f45 motor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      f24-9 (MR+) - f45-4 (RNFL) Always Below 1 Ω
      f24-10 (MR-) - f45-3 (RNBL) Always Below 1 Ω
      Result
      Result Proceed to
      OK (except Ottoman) A
      OK (for Ottoman) B
      NG C

    A

    REPLACE POSITION CONTROL ECU LH Click here

    B

    REPLACE POSITION CONTROL ECU LH Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (POWER SEAT MOTOR FUNCTION)


    1. Select the Active Test, use the intelligent tester to generate a control command, and then check the power seat motor function.

      Rear Right Seat
      Tester Display Test Part Control Range Diagnostic Note
      Rear Seat Lumbar Adjustment Seat lumbar operation Front / OFF / Rear -
      OK
      Motor operates normally.

    NG

    INSPECT REAR SEATBACK ASSEMBLY RH (POWER SEAT MOTOR) Click here

    OK

  10. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU RH - REAR POWER SEAT MOTOR RH)


    1. A000VKEE02
      *1 Front view of wire harness connector: (to Position Control ECU RH)
      *2 SSMR
      *3 Front view of wire harness connector: (to Rear Power Seat Motor RH)

      Disconnect the f39 ECU connector.

    2. Disconnect the f40 motor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      f39-17 (PVCC) - f40-5 (PVCC) Always Below 1 Ω
      f39-7 (SSMR) - f40-2 (SSMR) Always Below 1 Ω
      f39-23 (SGND) - f40-6 (GND) Always Below 1 Ω
      f39-17 (PVCC) - Body ground Always 10 kΩ or higher
      f39-7 (SSMR) - Body ground Always 10 kΩ or higher
      f39-23 (SGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK REAR SEATBACK ASSEMBLY RH (POSITION CONTROL SENSOR)


    1. A000WORE01
      *1 Front view of wire harness connector: (to Rear Power Seat Motor RH)

      Disconnect the f40 motor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      f40-5 (PVCC) - f40-6 (GND) Upper lumbar switch ON 7.2 to 8.8 V
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    B

    REPLACE POSITION CONTROL ECU RH Click here

    C

    REPLACE POSITION CONTROL ECU RH Click here

    A

  12. CHECK REAR SEATBACK ASSEMBLY RH (POSITION CONTROL SENSOR)


    1. A000WUVE02
      *1 Component with harness connected: (Rear Power Seat Motor RH)
      *2 SSMR

      Reconnect the f40 motor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Switch Condition Specified Condition
      f40-2 (SSMR) - Body ground Upper lumbar switch ON 0 to 8 V
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    B

    REPLACE REAR SEATBACK ASSEMBLY RH Click here

    C

    REPLACE REAR SEATBACK ASSEMBLY RH Click here

    A

  13. CHECK FOR DTC


    1. Clear the DTC Click here.

    2. Recheck for DTC.

      OK
      DTC B2656 is not output.
      Result
      Result Proceed to
      OK A
      NG (except Ottoman) B
      NG (for Ottoman) C

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE POSITION CONTROL ECU RH Click here

    C

    REPLACE POSITION CONTROL ECU RH Click here

  14. INSPECT REAR SEATBACK ASSEMBLY RH (POWER SEAT MOTOR)


    1. A000XLWE03
      *1 Component without harness connected: (Rear Power Seat Motor RH)

      Check operation of the power seat motor (upper lumbar motor).


      1. Check if the seatback moves smoothly when the battery is connected to the upper lumbar motor connector terminals.

        OK
        Measurement Condition Operational Direction

        Battery positive (+) → 3

        Battery negative (-) → 4

        		 Forward

        Battery positive (+) → 4

        Battery negative (-) → 3

        		 Backward
        Result
        Result Proceed to
        OK A
        NG (except Ottoman) B
        NG (for Ottoman) C

    B

    REPLACE REAR SEATBACK ASSEMBLY RH Click here

    C

    REPLACE REAR SEATBACK ASSEMBLY RH Click here

    A

  15. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU RH - REAR POWER SEAT MOTOR RH)


    1. A000UBDE02
      *1 Front view of wire harness connector: (to Position Control ECU RH)
      *2 Front view of wire harness connector: (to Rear Power Seat Motor RH)
      *3 RNFR
      *4 RNBR

      Disconnect the f4 ECU connector.

    2. Disconnect the f40 motor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      f4-9 (MR+) - f40-3 (RNFR) Always Below 1 Ω
      f4-10 (MR-) - f40-4 (RNBR) Always Below 1 Ω
      Result
      Result Proceed to
      OK (except Ottoman) A
      OK (for Ottoman) B
      NG C

    A

    REPLACE POSITION CONTROL ECU RH Click here

    B

    REPLACE POSITION CONTROL ECU RH Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR