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Home >> Lexus >> 2009 >> SC 430 >> Repair and Diagnosis >> Body & Frame >> Seats >> Front Power Seat Control System (Diagnostics) >> Front Power Seat Control System >> Front Power Seat does not Operate with Front Power Seat Switch >> Procedure
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Front Power Seat does not Operate with Front Power Seat Switch: Procedure

  1. INSPECT FUSE (D P/SEAT, P P/SEAT, MPX-IG, MPX-B1, D/C CUT, AM1) 
    1. Remove the D P/SEAT MPX-IG and AM1 fuses from the driver side junction block.
    2. Remove the P P/SEAT and MPX-B1 fuses from the front passenger side junction block.
    3. Remove the D/C CUT fuse from the engine room No. 1 relay block.
    4. Measure the resistance of the fuses.

      Standard resistance

      Below 1 Ω

    NG → REPLACE FUSE 

    OK: Go to next step 

  2. INSPECT IGNITION RELAY NO. 1 
    Fig 1: Identifying Ignition Relay No. 1
    GTY123564Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the IG1 relay from the driver side junction block.
    2. Measure the resistance of the relay.

      Standard resistance

      Tester Connection Specified Condition
      3 - 5 10 kΩ or higher
      3 - 5 Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

    NG → REPLACE IGNITION RELAY NO. 1 

    OK: Go to next step 

  3. CHECK FRONT POWER SEAT CONTROL FUNCTION 
    1. Check that each function of the power seat operates normally by using the front power seat switches.
      RESULT:

      Result Proceed to
      All front power switch operations are malfunctioning except lumbar front power seat switch operation A
      Only lumbar front power seat switch operation is malfunctioning B

    B → See step   8 

    A: Go to next step 

  4. READ VALUE USING TECHSTREAM (FRONT POWER SEAT SWITCH) 
    1. Check the Data List for proper functioning of the front power seat switch.
      DRIVER SEAT, PASSENGER SEAT

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Reclining Rear Reclining switch signal (Rearward)/ ON or OFF ON: Reclining switch (Rearward) is ON
      OFF: Reclining switch (Rearward) is OFF      		 -
      Reclining Front Reclining switch signal (Forward)/ ON or OFF ON: Reclining switch (Forward) is ON
      OFF: Reclining switch (Forward) is OFF      		 -
      Front Vertical Down Front vertical switch signal (Downward)/ ON or OFF ON: Front vertical switch (Downward) is ON
      OFF: Front vertical switch (Downward) is OFF      		 -
      Front Vertical Up Front vertical switch signal (Upward)/ ON or OFF ON: Front vertical switch (Upward) is ON
      OFF: Front vertical switch (Upward) is OFF      		 -
      Lifter Switch Down Lifter switch signal (Downward)/ ON or OFF ON: Lifter switch (Downward) is ON
      OFF: Lifter switch (Downward) is OFF      		 -
      Lifter Switch Up Lifter switch signal (Upward)/ ON or OFF ON: Lifter switch (Upward) is ON
      OFF: Lifter switch (Upward) is OFF      		 -
      Slide Rear Sliding switch signal (Rearward)/ ON or OFF ON: Sliding switch (Rearward) is ON
      OFF: Sliding switch (Rearward) is OFF      		 -
      Slide Front Sliding switch signal (Forward)/ ON or OFF ON: Sliding switch (Forward) is ON
      OFF: Sliding switch (Forward) is OFF      		 -

      OK

      On Techstream screen, each item changes between ON and OFF according to above chart.

    NG → See step   6 

    OK → REPLACE POSITION CONTROL ECU 

  5. INSPECT FRONT POWER SEAT SWITCH (SLIDE SWITCH, FRONT VERTICAL SWITCH, LIFTER SWITCH, RECLINING SWITCH) 
    1. Measure the resistance between the terminals when each switch is operated.
      1. Front power seat switch LH
        Fig 2: Identifying Front Power Seat Switch LH
        GTY141004Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard resistance

        Slide switch 

        Front vertical switch 

        Lifter switch 

        Reclining switch 

        Tester Connection Switch Condition Specified Condition
        1 (E) - 9 (SLDF) FRONT Below 1 Ω
        1 (E) - 6 (SLDR) BACK Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 10 (FUP) UP Below 1 Ω
        1 (E) - 5 (FDWN) DOWN Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 7 (LUP) UP Below 1 Ω
        1 (E) - 8 (LDWN) DOWN Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 3 (RCLF) FORWARD Below 1 Ω
        1 (E) - 2 (RCLR) REAR Below 1 Ω
      2. Front power seat switch RH
        Fig 3: Identifying Front Power Seat Switch RH
        GTY142520Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard resistance

        Slide switch 

        Front vertical switch 

        Lifter switch 

        Reclining switch 

        Tester Connection Switch Condition Specified Condition
        1 (E) - 9 (SLDF) FRONT Below 1 Ω
        1 (E) - 6 (SLDR) BACK Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 5 (FUP) UP Below 1 Ω
        1 (E) - 10 (FDWN) DOWN Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 8 (LUP) UP Below 1 Ω
        1 (E) - 7 (LDWN) DOWN Below 1 Ω
        Tester Connection Switch Condition Specified Condition
        1 (E) - 3 (RCLF) FORWARD Below 1 Ω
        1 (E) - 2 (RCLR) REAR Below 1 Ω

    NG → REPLACE FRONT POWER SEAT SWITCH 

    OK: Go to next step 

  6. INSPECT POWER SEAT MOTOR ASSEMBLY (SLIDE MOTOR, VERTICAL MOTOR, LIFTER MOTOR, RECLINING MOTOR) 
    1. Check the operation of the slide motor.
      Fig 4: Checking Operation Of Slide Motor
      GTY140167Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Check the motor rotation when the battery is connected to the slide motor connector terminals.

        OK

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Rotates smoothly counterclockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Rotates smoothly clockwise
    2. Check the operation of the vertical motor.
      Fig 5: Checking Operation Of Vertical Motor
      GTY144317Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Check the motor rotation when the battery is connected to the vertical motor connector terminals.

        OK

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Rotates smoothly counterclockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Rotates smoothly clockwise
    3. Check the operation of the lifter motor.
      Fig 6: Checking Operation Of Lifter Motor
      GTY140161Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Check the motor rotation when the battery is connected to the lifter motor connector terminals.

        OK

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Rotates smoothly counterclockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Rotates smoothly clockwise
    4. Check the operation of the reclining motor.
      Fig 7: Checking Operation Of Reclining Motor
      GTY128086Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Check the motor rotation when the battery is connected to the reclining motor connector terminals.

        OK

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Rotates smoothly counterclockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Rotates smoothly clockwise

    NG → REPLACE POWER SEAT MOTOR ASSEMBLY 

    OK: Go to next step 

  7. CHECK WIRE HARNESS (POSITION CONTROL ECU LH - BATTERY AND BODY GROUND) 
    Fig 8: Identifying P21, P22, P23 Or P24 ECU Connectors
    GTY133474Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the P21, P22, P23 or P24 ECU connectors.
    2. Measure the voltage of the wire harness side connectors.

      Standard voltage

      for Driver Side 

      for Front Passenger Side 

      Tester Connection Condition Specified Condition
      P21-8 (IG) - Body ground Ignition switch ON 10 to 14 V
      P21-8 (IG) - Body ground Ignition switch OFF Below 1 V
      P22-8 (+B) - Body ground Always 10 to 14 V
      P21-9 (SYSB) - Body ground Always 10 to 14 V
      Tester Connection Specified Condition
      P24-8 (+B) - Body ground 10 to 14 V
      P23-9 (SYSB) - Body ground 10 to 14 V
    3. Measure the resistance of the wire harness side connectors.

      Standard resistance

      for Driver Side 

      for Front Passenger Side 

      Tester Connection Specified Condition
      P21-13 (SGND) - Body ground Below 1 Ω
      P22-7 (GND) - Body ground Below 1 Ω
      Tester Connection Specified Condition
      P23-13 (SGND) - Body ground Below 1 Ω
      P24-7 (GND) - Body ground Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → REPLACE POSITION CONTROL ECU 

  8. CHECK WIRE HARNESS (LUMBAR FRONT POWER SEAT SWITCH - POSITION CONTROL ECU AND BODY GROUND) 
    Fig 9: Identifying Position Control ECU And Body Ground
    GTY121970Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the L27 or L28 switch connector.
    2. Disconnect the P22 or P24 ECU connector.
    3. Measure the resistance of the wire harness side connectors.

      Standard resistance

      for Driver Side 

      for Front Passenger Side 

      Tester Connection Specified Condition
      L27-4 (B2) - P22-8 (+B) Below 1 Ω
      L27-3 (E2) - Body ground Below 1 Ω
      Tester Connection Specified Condition
      L28-1 (B) - P24-8 (+B) Below 1 Ω
      L28-2 (E) - Body ground Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  9. INSPECT LUMBAR FRONT POWER SEAT SWITCH 
    Fig 10: Identifying Lumbar Front Power Seat Switch
    GTY130465Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Remove the switch.
    2. Measure the resistance of the seat switch.

      Standard resistance

      for Driver Side 

      for Front Passenger Side 

      Tester Connection Switch Condition Specified Condition
      1 (LF) - 4 (B2)
      2 (LR) - 3 (E2)      		 FRONT Below 1 Ω
      1 (LF) - 3 (E2)
      2 (LR) - 3 (E2)      		 OFF Below 1 Ω
      1(LF) - 3 (E2)
      2 (LR) - 4 (B2)      		 BACK Below 1 Ω
      Tester Connection Switch Condition Specified Condition
      1 (B) - 4 (LF)
      2 (E) - 3 (LR)      		 FRONT Below 1 Ω
      2 (E) - 3 (LR)
      2 (E) - 4 (LF)      		 OFF Below 1 Ω
      1 (B) - 3 (LR)
      2 (E) - 4 (LF)      		 BACK Below 1 Ω

    NG → REPLACE LUMBAR FRONT POWER SEAT SWITCH 

    OK: Go to next step 

  10. CHECK POWER SEAT MOTOR ASSEMBLY (LUMBAR SUPPORT ADJUSTER MOTOR) 
    Fig 11: Checking Operation Of Lumbar Support Adjuster Motor
    GTY117745Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Check the operation of the lumbar support adjuster motor.
      1. Check the motor rotation when the battery is connected to the lumbar support adjuster motor connector terminals.

        OK

        Measurement Condition Specified Condition
        Battery positive (+) → 1
        Battery negative (-) → 2        		 Rotates smoothly clockwise
        Battery positive (+) → 2
        Battery negative (-) → 1        		 Rotates smoothly counterclockwise

    NG → REPLACE POWER SEAT MOTOR ASSEMBLY 

    OK → REPAIR OR REPLACE HARNESS OR CONNECTOR 

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