DTC B2974 (F and MODE)

DTC B2974 or DTC indicator F and MODE  : A Problem in the Mode Control Motor B Circuit, Linkage, Door, or Motor (Front)

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. Check for DTCs.

   DTC Description	DTC
   B2974 A problem in the mode control motor B circuit, linkage, door, or motor (front)

   Is DTC B2974 or F and MODE indicated?

   YES 

   Go to step 2.

   NO 

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

2. Open wire check (M-DEF HD line)

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

   - 2. Disconnect the following connectors.

   Climate control unit connector A (32P)

   Mode control motor B 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
   	Mode control motor B 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 14 - 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	Mode control motor B 7P connector No. 6

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

   Is there continuity?

   YES 

   The M-DEF HD wire is not open. Go to step 3.

   NO 

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

3. Open wire check (M-HEAT HD line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Mode control motor B 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 13 - 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	Mode control motor B 7P connector No. 7

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

   Is there continuity?

   YES 

   The M-HEAT HD wire is not open. Go to step 4.

   NO 

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

4. Shorted wire check (M-DEF HD line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Mode control motor B 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 14 - 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 mode control motor B.

   NO 

   The M-DEF HD wire is OK. Go to step 5.

5. Shorted wire check (M-HEAT HD line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Mode control motor B 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 13 - 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 mode control motor B.

   NO 

   The M-HEAT HD wire is OK. Go to step 6.

6. Mode control motor B check

   - 1. Test the mode control motor B.

   Is the mode control motor B OK?

   YES 

   Replace the climate control unit .

   NO 

   Replace the mode control motor B , or repair the mode control linkage or door.