FRONT POWER SEAT CONTROL SYSTEM (for LHD), Diagnostic DTC:B2656

DTC Code DTC Name
B2656 Rear Seat Lumbar Adjustment Sensor Malfunction

DESCRIPTION

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

DTC Code DTC Detection Condition Trouble Area
B2656 The forward and backward lock detection position of the sensor is the same.

  • Position control ECU assembly

  • Front seat back adjuster assembly (Front seat back adjuster motor)

  • Harness or connector

WIRING DIAGRAM


  1. for Driver Side (Luxury Seat Type):

    A01FQI6E13

  2. for Front Passenger Side (Luxury Seat Type):

    A01FQI6E14

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK FOR DTC


    1. Check the parts which the DTCs have been output from Click here.

      Result
      Result Proceed to
      DTC output from "Driver Seat" A
      DTC output from "Passenger Seat" B

    B

    PERFORM ACTIVE TEST USING GTS (REAR SEAT LUMBAR ADJUSTMENT) Click here

    A

  2. PERFORM ACTIVE TEST USING GTS (REAR SEAT LUMBAR ADJUSTMENT)


    1. Turn the power switch off.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG).

    4. Turn the GTS on.

    5. Enter the following menus: Body Electrical / Driver Seat / Active Test.

    6. Perform the Active Test according to the display on the GTS.

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

    NG

    INSPECT FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

  3. CHECK POSITION CONTROL ECU ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR CIRCUIT)


    1. A01FSRQE19
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Disconnect the front seat back adjuster motor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      d26-2 (SMR) - d26-3 (MRE) Front seat back adjuster switch on 4.8 to 5.1 V

    NG

    CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY) Click here

    OK

  4. CHECK FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR)


    1. A01FR07E64
      Text in Illustration
      *a

      Component with harness connected

      (Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Reconnect the front seat back adjuster motor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      d26-2 (SMR) - Body ground Front seat back adjuster switch on 4.5 to 4.8 V

    NG

    REPLACE FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here

  5. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY)


    1. Disconnect the d4 and d5 position control ECU assembly connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      d4-9 (SSMR) - d26-2 (SMR) Always Below 1 Ω
      d5-20 (SGND) - d26-3 (MRE) Always Below 1 Ω
      d4-9 (SSMR) - Body ground Always 10 kΩ or higher
      d5-20 (SGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here

  6. INSPECT FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR)


    1. A01FVQQE16
      Text in Illustration
      *a

      Component without harness connected

      (Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Disconnect the d26 front seat back adjuster motor connector.

    2. Check if the front seat back adjuster motor moves smoothly when the battery is connected to the front seat back adjuster motor connector terminals.

      OK
      Measurement Condition Operational Direction

      Battery positive (+) → 4 (MR+)

      Battery negative (-) → 1 (MR-)

      		 Forward

      Battery positive (+) → 1 (MR-)

      Battery negative (-) → 4 (MR+)

      		 Backward

    NG

    REPLACE FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

  7. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY)


    1. Disconnect the d3 position control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      d3-1 (MR+) - d26-4 (MR+) Always Below 1 Ω
      d3-5 (MR-) - d26-1 (MR-) Always Below 1 Ω
      d3-1 (MR+) - Body ground Always 10 kΩ or higher
      d3-5 (MR-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here

  8. PERFORM ACTIVE TEST USING GTS (REAR SEAT LUMBAR ADJUSTMENT)


    1. Turn the power switch off.

    2. Connect the GTS to the DLC3.

    3. Turn the power switch on (IG).

    4. Turn the GTS on.

    5. Enter the following menus: Body Electrical / Passenger Seat / Active Test.

    6. Perform the Active Test according to the display on the GTS.

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

    NG

    INSPECT FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

  9. CHECK POSITION CONTROL ECU ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR CIRCUIT)


    1. A01FSRQE20
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Disconnect the front seat back adjuster motor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      c31-2 (SMR) - c31-3 (MRG) Front seat back adjuster switch on 4.8 to 5.1 V

    NG

    CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY) Click here

    OK

  10. CHECK FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR)


    1. A01FR07E65
      Text in Illustration
      *a

      Component with harness connected

      (Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Reconnect the front seat back adjuster motor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      c31-2 (SMR) - Body ground Front seat back adjuster switch on 4.5 to 4.8 V

    NG

    REPLACE FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here

  11. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY)


    1. Disconnect the c2 and c3 position control ECU assembly connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      c3-9 (SSMR) - c31-2 (SMR) Always Below 1 Ω
      c2-20 (SGND) - c31-3 (MRG) Always Below 1 Ω
      c3-9 (SSMR) - Body ground Always 10 kΩ or higher
      c2-20 (SGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here

  12. INSPECT FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR)


    1. A01FVQQE17
      Text in Illustration
      *a

      Component without harness connected

      (Front Seat Back Adjuster Assembly [Front Seat Back Adjuster Motor])

      Disconnect the c31 front seat back adjuster motor connector.

    2. Check if the front seat back adjuster motor moves smoothly when the battery is connected to the front seat back adjuster motor connector terminals.

      OK
      Measurement Condition Operational Direction

      Battery positive (+) → 4 (MR+)

      Battery negative (-) → 1 (MR-)

      		 Forward

      Battery positive (+) → 1 (MR-)

      Battery negative (-) → 4 (MR+)

      		 Backward

    NG

    REPLACE FRONT SEAT BACK ADJUSTER ASSEMBLY (FRONT SEAT BACK ADJUSTER MOTOR) Click here

    OK

  13. CHECK HARNESS AND CONNECTOR (POSITION CONTROL ECU ASSEMBLY - FRONT SEAT BACK ADJUSTER ASSEMBLY)


    1. Disconnect the c4 position control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      c4-1 (MR+) - c31-4 (MR+) Always Below 1 Ω
      c4-5 (MR-) - c31-1 (MR-) Always Below 1 Ω
      c4-1 (MR+) - Body ground Always 10 kΩ or higher
      c4-5 (MR-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POSITION CONTROL ECU ASSEMBLY Click here