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Home >> Lexus >> 2021 >> UX 200 Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Seats >> Seat Heater System (Diagnostic Codes & Symptom Tests) >> Seat Heater System >> Seat Heater for Front Left Seat does not Operate [07/2022 - ] >> Procedure

Seat Heater for Front Left Seat does not Operate [07/2022 - ]: Procedure

  1. CLEAR DTC 
    1. Clear the DTCs.

      Body Electrical > Air Conditioner > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR DTC 
    1. Check for DTCs.

      Body Electrical > Air Conditioner > Trouble Codes 

      OK

      DTC B14B5 and B14C0 are not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [07/2022 - ] 

    Result: 

    OK 

    See step  3

  3. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Body Electrical / Air Conditioner / Active Test.
    5. Perform the Active Test according to the display on the Techstream.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Front Left Seat Heater Front LH side seat heater operation OFF or ON -

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Front Left Seat Heater

      OK

      The seat heater operates normally.

      Result

      Result Proceed to
      OK A
      NG (for Standard Seat Type) B
      NG (for Sports Seat Type) C

    Result: 

    A 

    REPLACE REFRESHING SEAT SWITCH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    C 

    See step  12

    Result: 

    B 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER ASSEMBLY LH - BODY GROUND) 
    1. Disconnect the f5 front seat cushion heater assembly LH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      f5-2 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. INSPECT FRONT SEATBACK HEATER ASSEMBLY LH 
    1. Remove the front seatback heater assembly LH.

      Refer to REMOVAL [07/2022 - ]

    2. Inspect the front seatback heater assembly LH.

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK HEATER ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    OK 

    See step  6

  6. INSPECT FRONT SEAT CUSHION HEATER ASSEMBLY LH 
    1. Remove the front seat cushion heater assembly LH.

      Refer to REMOVAL [07/2022 - ]

    2. Inspect the front seat cushion heater assembly LH.

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the seat heater control sub-assembly LH connector.
      GTY798770Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Seat Heater Control Sub-assembly LH)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      f8-1 (+B1) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK SEAT HEATER CONTROL SUB-ASSEMBLY LH 
    1. Reconnect the f8 seat heater control sub-assembly LH connector.
    2. Disconnect the air conditioning amplifier assembly connector.
      GTY797547Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Amplifier Assembly)
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F49-15 (SHD+) - Body ground Ignition switch ON 5 to 13 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (SEAT HEATER CONTROL SUB-ASSEMBLY LH - FRONT SEAT CUSHION HEATER ASSEMBLY LH) 
    1. Disconnect the f8 seat heater control sub-assembly LH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      f8-7 (HTR1) - f5-1 (HTR) Always Below 1 Ω
      f8-7 (HTR1) or f5-1 (HTR) - Body ground Always 10 kΩ or higher
      f8-10 (E) - f5-6 (E) Always Below 1 Ω
      f8-10 (E) or f5-6 (E) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

  10. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Reconnect the air conditioning amplifier assembly connector.
    2. Reconnect the f5 front seat cushion heater assembly LH connector.
    3. Reconnect the f8 seat heater control sub-assembly LH connector.
    4. Remove the air conditioning amplifier assembly with its connectors still connected.

      Refer to REMOVAL [07/2022 - ]

    5. Measure the voltage according to the value(s) in the table below.
      GTY781368Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F49-15 (SHD+) - F51-4 (GND) Ignition switch ON, refreshing seat switch on (LO) Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

  11. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the f8 seat heater control sub-assembly RH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F49-15 (SHD+) - f8-5 (SWR) Always Below 1 Ω
      F49-15 (SHD+) or f8-5 (SWR) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH) - BODY GROUND) 
    1. Disconnect the f5 front seat cushion heater (front seat cushion pad with cover LH) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      f5-2 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  13

  13. INSPECT FRONT SEATBACK HEATER (FRONT SEATBACK PAD WITH COVER LH) 
    1. Remove the front seatback heater (front seatback pad with cover LH).

      Refer to REMOVAL [07/2022 - ]

    2. Inspect the front seatback heater (front seatback pad with cover LH).

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK HEATER (FRONT SEATBACK PAD WITH COVER LH). Refer to  REMOVAL [07/2022 - ] 

    Result: 

    OK 

    See step  14

  14. INSPECT FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH) 
    1. Remove the front seat cushion heater (front seat cushion pad with cover LH).

      Refer to REMOVAL [07/2022 - ]

    2. Inspect the front seat cushion heater (front seat cushion pad with cover LH).

      Refer to INSPECTION [10/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH). Refer to  REMOVAL [07/2022 - ] 

    Result: 

    OK 

    See step  15

  15. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the seat heater control sub-assembly LH connector.
      GTY798770Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Seat Heater Control Sub-assembly LH)
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      f8-1 (+B1) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  16

  16. CHECK SEAT HEATER CONTROL SUB-ASSEMBLY LH 
    1. Reconnect the f8 seat heater control sub-assembly LH connector.
    2. Disconnect the air conditioning amplifier assembly connector.
      GTY797547Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Amplifier Assembly)
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F49-15 (SHD+) - Body ground Ignition switch ON 5 to 13 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  19

    Result: 

    OK 

    See step  17

  17. CHECK HARNESS AND CONNECTOR (SEAT HEATER CONTROL SUB-ASSEMBLY LH - FRONT SEAT CUSHION HEATER (FRONT SEAT CUSHION PAD WITH COVER LH)) 
    1. Disconnect the f8 seat heater control sub-assembly LH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      f8-7 (HTR1) - f5-1 (HTR) Always Below 1 Ω
      f8-7 (HTR1) or f5-1 (HTR) - Body ground Always 10 kΩ or higher
      f8-10 (E) - f5-6 (E) Always Below 1 Ω
      f8-10 (E) or f5-6 (E) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  18

  18. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Reconnect the air conditioning amplifier assembly connector.
    2. Reconnect the f5 front seat cushion heater (front seat cushion pad with cover LH) connector.
    3. Reconnect the f8 seat heater control sub-assembly LH connector.
    4. Remove the air conditioning amplifier assembly with its connectors still connected.

      Refer to REMOVAL [07/2022 - ]

    5. Measure the voltage according to the value(s) in the table below.
      GTY781368Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F49-15 (SHD+) - F51-4 (GND) Ignition switch ON, refreshing seat switch on (LO) Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [07/2022 - ] 

  19. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the f8 seat heater control sub-assembly RH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F49-15 (SHD+) - f8-5 (SWR) Always Below 1 Ω
      F49-15 (SHD+) or f8-5 (SWR) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [07/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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