DTC B1221 (8) (HVAC Control Unit)

DTC B1221 or DTC indicator 8  : 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 HVAC 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 8 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 (female terminals) 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 (female terminals) No. 2:
   Test point 2	Rear mode control motor 7P connector (female terminals) 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 HVAC 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	HVAC control unit connector C (12P) No. 7
   Test point 2	Body ground

   Is there about 5 V?

   YES 

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

   NO 

   Replace the HVAC control unit .