DTC Troubleshooting: B1C55
DTC B1C55: Driver's Heater Thermistor Circuit Open
NOTE:
If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.
The front seat heater control unit does not turn on the front seat heater until the seat core temperature is 185 °F (85 °C) degrees or less. Make sure the seat core temperature is below 185 °F (85 °C) before troubleshooting.

DTC Description
DTC
B1C55 Driver's Heater Thermistor Circuit Open
  

1.
Problem verification:

Problem verification
?1.
Clear the DTCs with the HDS.


?2.
Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

?3.
Wait for at least 90 seconds.

?4.
Check for DTCs with the HDS.
DTC Description
DTC
B1C55 Driver's Heater Thermistor Circuit Open
  

Is DTC B1C55 indicated?

     
YES
     
     
     
Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Check for loose or poor connections.?
2.
Seat heater check 1:

Seat heater check 1
?1.
Disconnect the following connector.
Front seat heater control unit 14P connector

?2.
Measure the resistance between test points 1 and 2, refer to the following table.
Test condition
Vehicle OFF (LOCK) mode
Front seat heater control unit 14P connector: disconnected
Test point 1
Front seat heater control unit 14P connector No. 13
Test point 2
Front seat heater control unit 14P connector No. 7


Is resistance value within the range?

     
YES
     
     
     
     
NO
     
     
     
Go to step 3.
3.
Seat heater check 2:

Seat heater check 2
?1.
Disconnect the following connector.
Driver's seat cushion heater 4P connector

?2.
Measure the resistance between test points 1 and 2, refer to the following table.
Test condition
Vehicle OFF (LOCK) mode
Front seat heater control unit 14P connector: disconnected
Driver's seat cushion heater 4P connector: disconnected
Test point 1
Driver's seat cushion heater 4P connector No. 3
Test point 2
Driver's seat cushion heater 4P connector No. 4


Is resistance value within the range?

     
YES
     
     
     
     
NO: without power seat
     
     
     
Go to step 4.
     
NO: with power seat
     
     
     
Go to step 5.
4.
Open wire check (+THERMISTER(DR) line):

Open wire check (+THERMISTER(DR) line)
?1.
Connect terminals A and B with a jumper wire.
Terminal A
Driver's seat cushion heater 4P connector No. 3
Terminal B
Body ground


?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Front seat heater control unit 14P connector: disconnected
Driver's seat cushion heater 4P connector: disconnected
Driver's seat cushion heater 4P connector: jumped to body ground
Test point 1
Front seat heater control unit 14P connector No. 13
Test point 2
Body ground

Is there continuity?

     
YES
     
     
     
Repair an open or high resistance in the -THERMISTER(DR) wire.?
     
NO
     
     
     
Repair an open or high resistance in the +THERMISTER(DR) wire.?
5.
Open wire check (DR TH+ line):

Open wire check (DR TH+ line)
?1.
Connect terminals A and B with a jumper wire.
Terminal A
Driver's seat cushion heater 4P connector No. 3
Terminal B
Body ground


?2.
Check for continuity between test points 1 and 2.
Test condition
Vehicle OFF (LOCK) mode
Front seat heater control unit 14P connector: disconnected
Driver's seat cushion heater 4P connector: disconnected
Driver's seat cushion heater 4P connector: jumped to body ground
Test point 1
Front seat heater control unit 14P connector No. 13
Test point 2
Body ground

Is there continuity?

     
YES
     
     
     
Repair an open or high resistance in the DR TH- wire.?
     
NO
     
     
     
Repair an open or high resistance in the DR TH+ wire.?