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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Body & Frame >> Seats >> Seat Heater System - Diagnostic Codes & Symptom Tests >> Seat Heater System >> Seat Heater for Front Left Seat does not Operate [12/2019 - 11/2023] >> Procedure

Seat Heater for Front Left Seat does not Operate [12/2019 - 11/2023]: 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 B14C1 are not output.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO DIAGNOSTIC TROUBLE CODE CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 11/2023] 

    Result: 

    OK 

    See step  3

  3. PERFORM ACTIVE TEST USING GTS 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Front Left Seat Heater Front seat 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

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT HEATER SWITCH (AIR CONDITIONING CONTROL ASSEMBLY). Refer to  REMOVAL [12/2019 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (POWER SUPPLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT)) 
    1. Disconnect the e21 seat heater control sub-assembly LH (for front) connector.
      GTY843600Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Seat Heater Control Sub-assembly LH (for Front))
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      e21-1 (+B1) - Body ground Ignition switch ON 11 to 14 V
      e21-1 (+B1) - Body ground Ignition switch off Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  12

    Result: 

    OK 

    See step  5

  5. INSPECT FRONT SEATBACK HEATER ASSEMBLY LH 

    for Manual Seat: Refer to INSPECTION [12/2019 - ]

    for Power Seat: Refer to INSPECTION [12/2019 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK HEATER ASSEMBLY LH 

    for Manual Seat: Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    for Power Seat: Refer to REMOVAL [12/2019 - 10/2021] , or refer to REMOVAL [10/2021 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    OK 

    See step  6

  6. INSPECT FRONT SEAT CUSHION HEATER ASSEMBLY LH 

    for Manual Seat: Refer to INSPECTION [12/2019 - ]

    for Power Seat: Refer to INSPECTION [12/2019 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH 

    for Manual Seat: Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    for Power Seat: Refer to REMOVAL [12/2019 - 10/2021] , or refer to REMOVAL [10/2021 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER ASSEMBLY LH - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      e19-2 - 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 (SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT) - FRONT SEAT CUSHION HEATER ASSEMBLY LH) 
    1. Disconnect the e21 seat heater control sub-assembly LH (for front) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      e21-7 (HTR1) - e19-1 Always Below 1 Ω
      e21-7 (HTR1) or e19-1 - Body ground Always 10 kΩ or higher
      e21-10 (E) - e19-6 Always Below 1 Ω
      e21-10 (E) or e19-6 - 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. INSPECT SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT) 
    1. Reconnect the e21 seat heater control sub-assembly LH (for front) connector.
    2. Disconnect the H64 air conditioning amplifier assembly connector.
      GTY859884Courtesy 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 Condition Specified Condition
      H64-13 (SM1L) - Body ground Ignition switch ON 5 to 13 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  10

  10. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Reconnect the e21 seat heater control sub-assembly LH (for front) connector.
    2. Reconnect the H64 air conditioning amplifier assembly connector.
    3. Remove the air conditioning amplifier assembly with its connectors still connected.

      Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023]

    4. Measure the voltage according to the value(s) in the table below.
      GTY881506Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      H64-13 (SM1L) - H62-17 (GND) Ignition switch ON, front seat heater switch (air conditioning control assembly) on (LO) Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

  11. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT)) 
    1. Disconnect the e21 seat heater control sub-assembly LH (for front) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H64-13 (SM1L) - e21-5 (SWR) Always Below 1 Ω
      H64-13 (SM1L) or e21-5 (SWR) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT). Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. INSPECT S/HTR F/L RELAY 
    1. Inspect the S/HTR F/L relay.

      Refer to ON-VEHICLE INSPECTION [12/2019 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (POWER SUPPLY - S/HTR F/L RELAY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      S/HTR F/L relay holder terminal 1 - Body ground Ignition switch ON 11 V to 14 V
      S/HTR F/L relay holder terminal 1 - Body ground Ignition switch off Below 1 V
      S/HTR F/L relay holder terminal 3 - Body ground Ignition switch off*1
      Always*2      		 11 V to 14 V
      1. *1: for HV Model
      2. *2: for Gasoline Model

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  14

  14. CHECK HARNESS AND CONNECTOR (S/HTR F/L RELAY - SEAT HEATER CONTROL SUB-ASSEMBLY LH (FOR FRONT)) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      S/HTR F/L relay holder terminal 5 - e21-1 (+B1) Always Below 1 Ω
      S/HTR F/L relay holder terminal 5 or e21-1 (+B1) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  15

  15. CHECK HARNESS AND CONNECTOR (S/HTR F/L RELAY - BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      S/HTR F/L relay holder terminal 2 - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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