DTC : B1FA0

DTC B1FA0  : Left rear heater thermistor circuit open (second row seat)

DTC (Second Row Seat Heater Control Unit)

NOTE: 

• If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Go to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks .
• The seat heater control unit does not turn on the seat heater until the seat core temperature is 85 degrees or less. Make sure the seat core temperature is below 85 degrees before troubleshooting.

1. Problem verification

   -1. Clear the DTCs with the HDS.

   Clear DTCs

   - 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
   B1FA0 Left rear heater thermistor circuit open (second row seat)

   Is DTC B1FA0 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

   -1. Disconnect the following connector.

   Second row 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 Second row seat heater control unit 14P connector: disconnected
   Test point 1	Second row seat heater control unit 14P connector No. 13 - Refer to: Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Second row seat heater control unit 14P connector No. 7 - Refer to: Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2019 2020 2021) .

   Courtesy of HONDA, U.S.A., INC.

   Is resistance value within the range?

   YES 

   Replace the Second Row Seat Heater Control Unit - Removal and Installation .

   NO 

   Go to step 3.

3. Seat heater check 2

   -1. Disconnect the following connector.

   Left second row 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 Second row seat heater control unit 14P connector: disconnected Left second row seat heater connector A (4P): disconnected
   Test point 1	Left second row seat heater connector A (4P) No. 3
   Test point 2	Left second row seat heater connector A (4P) No. 2

   Courtesy of HONDA, U.S.A., INC.

   Courtesy of HONDA, U.S.A., INC.

   Is resistance value within the range?

   YES 

   Replace the Second Row Seat Heater Control Unit - Removal and Installation .

   NO 

   Go to step 4.

4. Open wire check (RR L TH+ line)

   -1. Connect terminals A and B with a jumper wire.

   Terminal A	Left second row seat heater connector A (4P) No. 3
   Terminal B	Body ground

   Courtesy of HONDA, U.S.A., INC.

   - 2. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Second row seat heater control unit 14P connector: disconnected Left second row seat heater connector A (4P): disconnected
   Test point 1	Second row seat heater control unit 14P connector No. 13 - Refer to: Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2016 2017 2018) or Second Row Seat Heater Control Unit Connector for Inputs and Outputs (2019 2020 2021) .
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair an open or high resistance in the RR L TH- wire.

   NO 

   Repair an open or high resistance in the RR L TH+ wire.