DTC Troubleshooting: B121A (B-B1), B121A (49)

DTC B121A or DTC screen B-B1 or DTC indicator 49  : An open in the 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 and then the ON mode.

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

   -4. Check for DTCs.

   DTC Description	DTC
   B121A An open in the mode control motor circuit

   Is DTC B121A, Error on the DTC screen B-B1 (climate control panel without display) or 49 (climate control panel with display) indicated?

   YES 

   Go to step 2.

   NO 

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

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

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

   -2. Disconnect the following connector.

   Mode control motor 5P connector

   -3. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode
   	Mode control motor 5P connector: disconnected
   Test point 1	Mode control motor 5P connector (female terminals) No. 2:
   Test point 2	Body ground

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

   Is there about 5 V?

   YES 

   The MDD-P wire is OK. Go to step 3.

   NO 

   Go to step 4.

3. Open wire check (SENS-COM line)

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

   Test condition	Vehicle ON mode
   	Mode control motor 5P connector: disconnected
   Test point 1	Mode control motor 5P connector (female terminals) No. 2:
   Test point 2	Mode control motor 5P connector (female terminals) No. 1:

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

   Is there about 5 V?

   YES 

   Replace the mode control motor .

   NO 

   Repair an open in the SENS-COM wire.

4. Open wire check (MDD-P line)

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

   Test condition	Vehicle ON mode
   	Mode control motor 5P connector: disconnected
   Test point 1	Climate control unit connector B (24P) No. 5
   Test point 2	Body ground

   Is there about 5 V?

   YES 

   Repair an open in the MDD-P wire.

   NO 

   Replace the climate control unit .