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) 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 24P 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 24P connector: disconnected
Test point 1
Front seat heater control unit 24P connector No. 12
Test point 2
Front seat heater control unit 24P connector No. 22


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 heater connector A (4P)

?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 24P connector: disconnected
Driver's seat heater connector A (4P): disconnected
Test point 1
Driver's seat heater connector A (4P) (male terminals) No. 3:
Test point 2
Driver's seat heater connector A (4P) (male terminals) No. 4:


Is resistance value within the range?

     
YES
     
     
     
Go to step 4.
     
NO
     
     
     
4.
Open wire check (TH? DR line):

Open wire check (TH? DR line)
?1.
Connect terminals A and B with a jumper wire.
Terminal A
Driver's seat heater connector A (4P) (female terminals) 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 24P connector: disconnected
Driver's seat heater connector A (4P) : disconnected
Test point 1
Front seat heater control unit 24P connector No. 12
Test point 2
Body ground

Is there continuity?

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