Seat Heater for Front Left Seat does not Operate [11/2023 - ]: Procedure

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

   Front seat LH side seat heater operates normally.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

GO TO AIR CONDITIONING SYSTEM 

for HV Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]

for Gasoline Model: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ]

Result: 

NG 

See step  2

1. Disconnect the e21 seat heater control sub-assembly LH connector.

   Courtesy 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
   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  9

Result: 

OK 

See step  3

1. Disconnect the H64 air conditioning amplifier assembly 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: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Disconnect the e19 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
   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
   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  5

Refer to INSPECTION [12/2019 - ]

Result

Result: 

NG 

REPLACE FRONT SEAT CUSHION HEATER ASSEMBLY LH. Refer to  REMOVAL [11/2023 - ] 

Result: 

OK 

See step  6

Refer to INSPECTION [12/2019 - ]

Result

Result: 

NG 

REPLACE FRONT SEATBACK HEATER ASSEMBLY LH. Refer to  REMOVAL [11/2023 - ] 

Result: 

OK 

See step  7

1. Temporarily replace the seat heater control sub-assembly LH with a new or known good one.

   Refer to REMOVAL [11/2023 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  8

1. Check the front seat LH side seat heater operation.

   Refer to OPERATION CHECK [12/2019 - ]

   OK

   Front seat LH side 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 [11/2023 - ] 

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

Result

Result: 

NG 

REPLACE S/HTR F/L RELAY 

Result: 

OK 

See step  10

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	11 V to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  11

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  12

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