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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Accessories & Equipment >> Seats >> Seat Heater System - Diagnostic Codes & Symptom Tests (Coupe) >> Seat Heater System >> Seat Heater for Front Left Seat does not Operate [03/2017 - ] >> Procedure

Seat Heater for Front Left Seat does not Operate [03/2017 - ]: Procedure

  1. CLEAR DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - ]

      Body Electrical > Air Conditioner > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR DTC 
    1. Check for DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - ]

      Body Electrical > Air Conditioner > Trouble Codes 

      OK

      DTC B14C1 is not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [03/2017 - ] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (SEAT HEATER CONTROL SUB-ASSEMBLY LH - BATTERY) 
    1. Disconnect the seat heater control sub-assembly LH connector.
      GTY788105Courtesy 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 Condition Specified Condition
      w9-3 (IG) - Body ground Engine switch on (IG) 11 to 14 V
      Engine switch off Below 1 V
      w9-1 (+B1) - Body ground Always 11 to 14 V
      w9-8 (+B2) - Body ground Always 11 to 14 V

      Result

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

    Result: 

    B 

    See step  12

    Result: 

    C 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  4

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

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

    2. Inspect the front seat cushion heater assembly LH.

      Refer to INSPECTION [03/2017 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    OK 

    See step  5

  5. INSPECT FRONT SEATBACK SUB-ASSEMBLY LH 
    1. Remove the front seatback sub-assembly LH.

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

    2. Inspect the front seatback sub-assembly LH.

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK SUB-ASSEMBLY LH. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    OK 

    See step  6

  6. INSPECT SEPARATE TYPE FRONT SEATBACK COVER LH 
    1. Remove the separate type front seatback cover RH.

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

    2. Inspect the separate type front seatback cover RH.

      Refer to INSPECTION [03/2017 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE SEPARATE TYPE FRONT SEATBACK COVER LH. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER ASSEMBLY LH - SEAT HEATER CONTROL SUB-ASSEMBLY LH AND BODY GROUND) 
    1. Disconnect the w5 front seat cushion heater assembly LH connector.
    2. Disconnect the w9 seat heater control sub-assembly LH connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      w5-6 - w9-10 (E) Always Below 1 Ω
      w5-6 or w9-10 (E) - Other terminals and body ground Always 10 kΩ or higher
      w5-1 - w9-7 (Heater Output 1) Always Below 1 Ω
      w5-1 or w9-7 (Heater Output 1) - Other terminals and body ground Always 10 kΩ or higher
      w5-3 - w9-12 (Heater Output 2) Always Below 1 Ω
      w5-3 or w9-12 (Heater Output 2) - Other terminals and body ground Always 10 kΩ or higher
      w5-2 - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER ASSEMBLY LH - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the w5 front seat cushion heater assembly LH connector.
    2. Disconnect the P56 and P57 air conditioning amplifier assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      w5-4 - P56-17 (TSL) Always Below 1 Ω
      w5-4 or P56-17 (TSL) - Other terminals and body ground Always 10 kΩ or higher
      w5-5 - P57-8 (SG-5) Always Below 1 Ω
      w5-5 or P57-8 (SG-5) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK HARNESS AND CONNECTOR (SEAT HEATER CONTROL SUB-ASSEMBLY LH - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the w9 seat heater control sub-assembly LH connector.
    2. Disconnect the P56 air conditioning amplifier assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      w9-4 (PWM) - P56-15 (SHD+) Always Below 1 Ω
      w9-4 (PWM) or P56-15 (SHD+) - Other terminals and 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. REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH 
    1. Temporarily replace the seat heater control sub-assembly LH with a new or known good one.

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  11

  11. CHECK SEAT HEATER OPERATION 
    1. Check the seat heater.

      Refer to OPERATION CHECK [03/2017 - 05/2023] , or refer to OPERATION CHECK [05/2023 - ]

      OK

      The seat heater operates normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    END (SEAT HEATER CONTROL SUB-ASSEMBLY LH WAS DEFECTIVE) 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [03/2017 - ] 

  12. INSPECT FRONT SEAT CUSHION PAD WITH COVER LH 
    1. Remove the front seat cushion pad with cover LH.

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

    2. Inspect the front seat cushion pad with cover LH.

      Refer to INSPECTION [03/2017 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEAT CUSHION PAD WITH COVER LH. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    OK 

    See step  13

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

      Refer to REMOVAL [03/2017 - 05/2023] , or refer to REMOVAL [05/2023 - ]

    2. Inspect the front seatback pad with cover LH.

      Refer to INSPECTION [03/2017 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK PAD WITH COVER LH. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    OK 

    See step  14

  14. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION PAD WITH COVER LH - SEAT HEATER CONTROL SUB-ASSEMBLY LH AND BODY GROUND) 
    1. Disconnect the w5 front seat cushion pad with cover LH connector.
    2. Disconnect the w9 seat heater control sub-assembly LH connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      w5-6 - w9-10 (E) Always Below 1 Ω
      w5-6 or w9-10 (E) - Other terminals and body ground Always 10 kΩ or higher
      w5-1 - w9-7 (Heater Output 1) Always Below 1 Ω
      w5-1 or w9-7 (Heater Output 1) - Other terminals and body ground Always 10 kΩ or higher
      w5-3 - w9-12 (Heater Output 2) Always Below 1 Ω
      w5-3 or w9-12 (Heater Output 2) - Other terminals and body ground Always 10 kΩ or higher
      w5-2 - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  15

  15. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION PAD WITH COVER LH - AIR CONDITIONING AMPLIFIER ASSEMBLY) 
    1. Disconnect the w5 front seat cushion pad with cover LH connector.
    2. Disconnect the P56 and P57 air conditioning amplifier assembly connectors.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      w5-4 - P56-17 (TSL) Always Below 1 Ω
      w5-4 or P56-17 (TSL) - Other terminals and body ground Always 10 kΩ or higher
      w5-5 - P57-8 (SG-5) Always Below 1 Ω
      w5-5 or P57-8 (SG-5) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    See step  9

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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