DTC B1221 (G and MODE)

DTC B1221 or DTC indicator G and MODE  : An Open in the Rear Mode Control Motor Circuit

DTCs (AC)

1. Problem verification

   - 1. Clear the DTCs with the HDS.

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

   - 3. Do the Self-Diagnostic Function with the HDS or the climate control unit.

   - 4. Wait for at least 8 seconds.

   - 5. Check for DTCs.

   DTC Description	DTC
   B1221 An open in the rear mode control motor circuit

   Is DTC B1221 or G and MODE indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure. Check for loose wires or poor connections on the rear mode control motor circuit.

2. Determine possible failure area (MOD-P RR line, others)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connector.

   Rear mode control motor 7P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Rear mode control motor 7P connector: disconnected
   Test point 1	Rear mode control motor 7P connector No. 2
   Test point 2	Body ground

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

   Is there about 5 V?

   YES 

   The MOD-P RR wire is OK. Go to step 3.

   NO 

   Go to step 4.

3. Open wire check (SENSOR(COM) line)

   - 1. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Rear mode control motor 7P connector: disconnected
   Test point 1	Rear mode control motor 7P connector No. 2
   Test point 2	Rear mode control motor 7P connector No. 3

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

   Is there about 5 V?

   YES 

   Replace the rear mode control motor .

   NO 

   Repair an open in the wire between the climate control unit and the rear mode control motor.

4. Open wire check (MOD-P RR line)

   - 1. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Rear mode control motor 7P connector: disconnected
   Test point 1	Climate control unit connector C (12P) No. 7 - Refer to: Climate Control Unit Connector For Inputs and Outputs (2019 2020 2021), or Climate Control Unit Connector For Inputs and Outputs (2016 2017 2018)
   Test point 2	Body ground

   Is there about 5 V?

   YES 

   Repair an open in the wire between the climate control unit and the rear mode control motor.

   NO 

   Replace the climate control unit .