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Home >> Lexus >> 2021 >> ES 300h Luxury >> Repair and Diagnosis >> Accessories & Equipment >> Seats >> Seat Heater System (Hybrid) - Diagnostic Codes & Symptom Tests >> SEAT HEATER SYSTEM (for HV Model) >> Seat Heater for Front Left Seat does not Operate [06/2018 - 08/2021] >> Procedure

Seat Heater for Front Left Seat does not Operate [06/2018 - 08/2021]: 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 [06/2018 - 08/2021] 

    Result: 

    OK 

    See step  3

  3. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    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 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 SEAT HEATER SWITCH (REFRESHING SEAT SWITCH). Refer to  REMOVAL [06/2018 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (FRONT SEAT CUSHION HEATER ASSEMBLY LH - BODY GROUND) 
    1. Disconnect the U39 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
      U39-2 - 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.

      for TMC Made: Refer to REMOVAL [06/2018 - 08/2021]

      for TMMK Made: Refer to REMOVAL [06/2018 - 08/2021]

    2. Inspect the front seatback heater assembly LH.

      for TMC Made: Refer to INSPECTION [06/2018 - 08/2021]

      for TMMK Made: Refer to INSPECTION [06/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FRONT SEATBACK HEATER ASSEMBLY LH 

    for TMC Made: Refer to REMOVAL [06/2018 - 08/2021]

    for TMMK Made: Refer to REMOVAL [06/2018 - 08/2021]

    Result: 

    OK 

    See step  6

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

      for TMC Made: Refer to REMOVAL [06/2018 - 08/2021]

      for TMMK Made: Refer to REMOVAL [06/2018 - 08/2021]

    2. Inspect the front seat cushion heater assembly LH.

      for TMC Made: Refer to INSPECTION [06/2018 - 08/2021]

      for TMMK Made: Refer to INSPECTION [06/2018 - ]

      Result

      Result Proceed to
      OK (for TMC Made) A
      OK (for TMMK Made) B
      NG C

    Result: 

    B 

    See step  12

    Result: 

    C 

    REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY RH 

    for TMC Made: Refer to REMOVAL [06/2018 - 08/2021]

    for TMMK Made: Refer to REMOVAL [06/2018 - 08/2021]

    Result: 

    A 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the U45 seat heater control sub-assembly RH connector.
      GTY798776Courtesy 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
      U45-1 (+B1) - Body ground Power switch on (IG) 11 to 14 V
      U45-1 (+B1) - Body ground Power 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 U45 seat heater control sub-assembly LH connector.
    2. Disconnect the G41 air conditioning amplifier assembly connector.
      GTY832167Courtesy 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
      G41-15 (SHD+) - Body ground Power switch on (IG) 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 U45 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
      U45-7 (HTR1) - U39-1 Always Below 1 Ω
      U45-7 (HTR1) or U39-1 - Body ground Always 10 kΩ or higher
      U45-10 (E) - U39-6 Always Below 1 Ω
      U45-10 (E) or U39-6 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

  10. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Reconnect the G41 air conditioning amplifier assembly connector.
    2. Reconnect the U45 seat heater control sub-assembly RH connector.
    3. Remove the air conditioning amplifier assembly with its connectors still connected.

      Refer to REMOVAL [06/2018 - 08/2020] , or refer to REMOVAL [08/2020 - ]

    4. Measure the voltage according to the value(s) in the table below.
      GTY781376Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      G41-15 (SHD+) - G39-4 (GND) Power switch on (IG), refreshing seat switch on (LO) Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY RH. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - ] 

  11. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - SEAT HEATER CONTROL SUB-ASSEMBLY LH) 
    1. Disconnect the U45 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
      G41-15 (SHD+) - U45-5 (SWR) Always Below 1 Ω
      G41-15 (SHD+) or U45-5 (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 [06/2018 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  12. CHECK HARNESS AND CONNECTOR (IG POWER SUPPLY - FRONT SEAT CUSHION HEATER ASSEMBLY LH - BODY GROUND) 
    1. Disconnect the U39 front seat cushion heater assembly LH connector.
      GTY831244Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Front Seat Cushion Heater Assembly LH)
    2. Measure the voltage and resistance according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      U39-1 - Body ground Power switch on (IG) 11 to 14 V
      U39-1 - Body ground Power switch off Below 1 V

      Standard Resistance

      Tester Connection Condition Specified Condition
      U39-2 - 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. CHECK FRONT SEAT CUSHION HEATER ASSEMBLY LH 
    1. Reconnect the U39 front seat cushion heater assembly LH connector.
      GTY797526Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Amplifier Assembly)
    2. Disconnect the G41 air conditioning amplifier assembly connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      G41-15 (SHD+) - Body ground Power switch on (IG) 5 to 13 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  15

    Result: 

    OK 

    See step  14

  14. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Reconnect the G41 air conditioning amplifier assembly connector.
    2. Remove the air conditioning amplifier assembly with its connectors still connected.

      Refer to REMOVAL [06/2018 - 08/2020] , or refer to REMOVAL [08/2020 - ]

    3. Measure the voltage according to the value(s) in the table below.
      GTY781375Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Air Conditioning Amplifier Assembly)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      G41-15 (SHD+) - G39-4 (GND) Power switch on (IG), seat heater switch (refreshing seat heater switch) on (LO) Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - ] 

  15. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - FRONT SEAT CUSHION HEATER ASSEMBLY LH) 
    1. Disconnect the U39 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
      G41-15 (SHD+) - U39-6 Always Below 1 Ω
      G41-15 (SHD+) or U39-6 - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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