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Home >> Toyota >> 2021 >> Mirai Limited >> Repair and Diagnosis >> Accessories & Equipment >> Seats >> Seat Heater System - Diagnostic Codes & Symptom Tests >> Seat Heater System >> Seat Heater for Rear Right Seat does not Operate [11/2020 - 12/2023] >> Procedure

Seat Heater for Rear Right Seat does not Operate [11/2020 - 12/2023]: Procedure

  1. PERFORM ACTIVE TEST USING GTS (SEAT HEATER) 
    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
      Rear Right Seat Heater Rear right seat heater operation OFF/ON -

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Rear Right Seat Heater

      OK

      Rear seat heater operates normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  2

  2. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Replace the air conditioner amplifier assembly with a new one or known good one.

      Refer to REMOVAL [11/2020 - ]

      Result

      Proceed to
      OK

    Result: 

    OK 

    See step  3

  3. CHECK REAR SEAT HEATER OPERATION 
    1. Check the rear seat heater operation.

      Refer to OPERATION CHECK [11/2020 - ]

      OK

      Rear seat heater operates normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    END (AIR CONDITIONING CONTROL ASSEMBLY WAS DEFECTIVE) 

    Result: 

    NG 

    REPLACE COOLER CONTROL SWITCH ASSEMBLY. Refer to  REMOVAL [11/2020 - ] 

  4. CHECK HARNESS AND CONNECTOR (REAR SEAT HEATER CONTROL SUB-ASSEMBLY RH POWER SOURCE CIRCUIT) 
    1. Disconnect the M5 rear seat heater control sub-assembly RH connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      M5-1 (B1) - Body ground Ignition switch ON 11 to 14 V
      M5-1 (B1) - Body ground Ignition switch off Below 1 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (AIR CONDITIONER AMPLIFIER ASSEMBLY - SEAT HEATER CONTROL SUB-ASSEMBLY RH) 
    1. Disconnect the D79 air conditioning amplifier assembly connector.
    2. Disconnect the M5 rear seat heater control sub-assembly RH connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D79-23 (SM2R) - M5-5 (SWR) Always Below 1 Ω
      D79-23 (SM2R) or M5-5 (SWR) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (SEATBACK HEATER ASSEMBLY LH - SEAT HEATER CONTROL SUB-ASSEMBLY RH) 
    1. Disconnect the M6 seatback heater assembly RH connector.
    2. Disconnect the M5 rear seat heater control sub-assembly RH connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      M6-4 - M5-10(E) Always Below 1 Ω
      M6-1 - M5-7(HTR) Always Below 1 Ω
      M6-4 or M5-10 (E) - Body ground Always 10 kΩ or higher
      M6-1 or M5-7(HTR) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (SEATBACK HEATER ASSEMBLY RH - BODY GROUND) 
    1. Disconnect the M6 seatback heater assembly RH connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      M6-5 - Body ground Always Below 1 Ω
      M6-5 - Other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. INSPECT SEATBACK HEATER ASSEMBLY RH 

    Refer to INSPECTION [11/2020 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE SEATBACK HEATER ASSEMBLY RH. Refer to  REMOVAL [11/2020 - ] 

    Result: 

    OK 

    See step  9

  9. INSPECT SEAT CUSHION HEATER ASSEMBLY RH 

    Refer to INSPECTION [11/2020 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE SEAT CUSHION HEATER ASSEMBLY RH. Refer to  REMOVAL [11/2020 - ] 

    Result: 

    OK 

    See step  10

  10. REPLACE RAER SEAT HEATER CONTROL SUB-ASSEMBLY RH 
    1. Replace the rear seat heater control sub-assembly RH with a new one or known good one.

      Refer to REMOVAL [11/2020 - ]

      Result

      Proceed to
      OK

    Result: 

    OK 

    See step  11

  11. CHECK REAR SEAT HEATER OPERATION 
    1. Check the rear seat heater operation.

      Refer to OPERATION CHECK [11/2020 - ]

      OK

      Rear right side seat heater operates normally.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    END (REAR SEAT HEATER CONTROL SUB-ASSEMBLY RH WAS DEFECTIVE) 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [11/2020 - ]