Seat Heater for Front Left Seat does not Operate [11/2020 - 12/2022]: 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	Driver seat heater operation	OFF/ON	-

   Body Electrical > Air Conditioner > Active Test 

   Tester Display
   Front Left Seat Heater

   OK

   Driver seat heater operates normally.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  3

Result: 

OK 

See step  2

1. Check the seat heater operation.

   Refer to OPERATION CHECK [11/2020 - ]

   OK

   The seat heater operates normally.

   Result

   Result	Proceed to
   Does not operate normally with operation of either the multi-display or seat heater switch	A
   Does not operate normally with operation of the multi-display	B
   Does not operate normally with operation of the seat heater switch	C

Result: 

A 

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

Result: 

B 

GO TO TOYOTA MULTI OPERATION TOUCH SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2020 - 12/2022] 

Result: 

C 

REPLACE AIR CONDITIONING CONTROL ASSEMBLY. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022] 

1. Disconnect the L40 seat heater control sub-assembly LH connector.
2. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   L40-1 (+B1) - Body ground	Ignition switch ON	11 to 14 V
   L40-1 (+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  4

1. Disconnect the D79 air conditioning amplifier assembly connector.
2. Disconnect the L40 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
   D79-13 (SM1L) - L40-5 (SWR)	Always	Below 1 Ω
   D79-13 (SM1L) or L40-5 (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  5

1. Disconnect the L35 front seat cushion heater assembly LH connector.
2. Disconnect the L40 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
   L35-6 - L40-10 (E)	Always	Below 1 Ω
   L35-6 or L40-10 (E) - Body ground	Always	10 kΩ or higher
   L35-1 - L40-7 (HTR1)	Always	Below 1 Ω
   L35-1 or L40-7 (HTR1) - Body ground	Always	10 kΩ or higher
   L35-2 - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  6

Refer to INSPECTION [11/2020 - ]

Result

Result: 

NG 

REPLACE SEAT HEATER CONTROL SUB-ASSEMBLY LH. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022] 

Result: 

OK 

See step  7

Refer to INSPECTION [11/2020 - ]

Result

Result: 

NG 

REPLACE FRONT SEATBACK HEATER ASSEMBLY LH. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022] 

Result: 

OK 

See step  8

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

   Refer to REMOVAL [11/2020 - 11/2021] , or refer to REMOVAL [11/2021 - 12/2022]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  9

1. Check the seat heater operation.

   Refer to OPERATION CHECK [11/2020 - ]

   OK

   Front left 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 [11/2020 - ]