DTC B1235 (D and Windshield Defrost)

DTC B1235 or DTC indicator D and WINDSHIELD DEFROST  : A Problem in the Air Mix Control Motor Circuit, Linkage, Door, or Motor (Driver's)

DTC (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. Check for DTCs.

   DTC Description	DTC
   B1235 A problem in the air mix control motor circuit, linkage, door, or motor (driver's)

   Is DTC B1235 or D and WINDSHIELD DEFROST indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure. Check for loose wires or poor connections on the driver's air mix control motor circuit.

2. Open wire check (M HOT DR line)

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

   - 2. Disconnect the following connectors.

   Climate control unit connector A (32P)

   Driver's air mix control motor 7P connector

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Driver's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) 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	Driver's air mix control motor 7P connector No. 7

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

   Is there continuity?

   YES 

   The M HOT DR wire is not open. Go to step 3.

   NO 

   Repair an open in the wire between the climate control unit and the driver's air mix control motor.

3. Open wire check (M COOL DR line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Driver's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 8 - 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	Driver's air mix control motor 7P connector No. 6

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

   Is there continuity?

   YES 

   The M COOL DR wire is not open. Go to step 4.

   NO 

   Repair an open in the wire between the climate control unit and the driver's air mix control motor.

4. Shorted wire check (M HOT DR line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Driver's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) 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 continuity?

   YES 

   Repair a short to body ground in the wire between the climate control unit and the driver's air mix control motor.

   NO 

   The M HOT DR wire is OK. Go to step 5.

5. Shorted wire check (M COOL DR line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Driver's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 8 - 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 continuity?

   YES 

   Repair a short to body ground in the wire between the climate control unit and the driver's air mix control motor.

   NO 

   The M COOL DR wire is OK. Go to step 6.

6. Driver's air mix control motor check

   - 1. Test the driver's air mix control motor.

   Is the driver's air mix control motor OK?

   YES 

   Replace the climate control unit .

   NO 

   Replace the driver's air mix control motor , or repair the driver's air mix control linkage or door.