DTC B1237 (F and Windshield Defrost)

DTC B1237 or DTC indicator F and WINDSHIELD DEFROST  : A Short in the Passenger's Air Mix Control Motor Circuit

DTC (AC)

1. Problem verification

   - 1. Clear the DTC 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
   B1237 A short in the passenger's air mix control motor circuit

   Is DTC B1237 or F and WINDSHIELD DEFROST indicated?

   YES 

   Go to step 2.

   NO 

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

2. Determine possible failure area (SENSOR 5V line, others)

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

   - 2. Disconnect the following connector.

   Passenger's air mix 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
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Passenger's air mix control motor 7P connector No. 1
   Test point 2	Body ground

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

   Is there about 5 V?

   YES 

   The SENSOR 5V wire is OK. Go to step 3.

   NO 

   Go to step 6.

3. Passenger's air mix control motor check (AMDP AS line)

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

   Test condition	Vehicle ON mode
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Passenger's air mix control motor 7P connector No. 2

   Test point 2

   Body ground

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

   Is there about 5 V?

   YES 

   Replace the passenger's air mix control motor .

   NO 

   Go to step 4.

4. Shorted wire check (AMDP AS line)

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

   - 2. Disconnect the following connector.

   Climate control unit connector C (12P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector C (12P): disconnected
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector C (12P) No. 2 - 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 passenger's air mix control motor.

   NO 

   The AMDP AS wire is not shorted. Go to step 5.

5. Shorted wire check (AMDP AS line to SENSOR(COM) line)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector C (12P): disconnected
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Passenger's air mix control motor 7P connector No. 2
   Test point 2	Passenger's air mix control motor 7P connector No. 3

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

   Is there continuity?

   YES 

   Repair a short in the wires between the climate control unit and the passenger's air mix control motor.

   NO 

   The AMDP AS wire to SENSOR(COM) wire are OK. Replace the climate control unit .

6. Open wire check (SENSOR 5V line)

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

   Test condition	Vehicle ON mode
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 5 - 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 passenger's air mix control motor.

   NO 

   The SENSOR 5V wire is not open. Go to step 7.

7. Shorted wire check (SENSOR 5V line)

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

   - 2. Disconnect the following connector.

   Climate control unit connector A (32P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Climate control unit connector A (32P): disconnected
   	Passenger's air mix control motor 7P connector: disconnected
   Test point 1	Climate control unit connector A (32P) No. 5 - 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 passenger's air mix control motor.

   NO 

   The SENSOR 5V wire is OK. Replace the climate control unit .