DTC B14E6: Mode Door Actuator Stepping Motor Circuit Short-Circuit

DTC detecting condition: 

Short circuit in the mode door actuator stepping motor circuit (short circuit to motor coil power supply) is detected for 3 seconds or more.

Trouble symptom: 

Vent does not change.

Wiring diagram: 

Air conditioning system Refer to WIRING SYSTEM>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR. 
   1. Check the condition of connector connection.
   2. Read the DTC using Subaru Select Monitor. Refer to HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B14E6 displayed?

   Yes:  Go to  2.

   No  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK POWER SUPPLY FOR MODE DOOR ACTUATOR. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the mode door actuator connector.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between the mode door actuator connector terminal and chassis ground.

   Connector & terminal 

   (B77) No. 3 (+) - Chassis ground (-):

   Is the voltage approx. 10 V or more?

   Yes:  Go to  3.

   No  Check the DC power supply circuit.

3. CHECK MODE DOOR ACTUATOR. 
   1. Turn the ignition switch to OFF.
   2. Measure the internal resistance of the mode door actuator using a tester.

   Terminals 

   Mode door actuator

   No. 3 - No. 1:

   No. 3 - No. 2:

   No. 3 - No. 5:

   No. 3 - No. 6:

   Is the resistance 80 - 100 Ω?

   Yes:  Go to  4.

   No  Replace the actuator. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>MODE DOOR ACTUATOR>REMOVAL .

4. CHECK HARNESS BETWEEN A/C CONTROL PANEL AND MODE DOOR ACTUATOR (SHORTED TO POWER SUPPLY). 
   1. Disconnect the A/C control panel connector.
   2. Measure the voltage between mode door actuator connector and chassis ground.

   Connector & terminal 

   (B77) No. 1 (+) - Chassis ground (-):

   (B77) No. 2 (+) - Chassis ground (-):

   (B77) No. 5 (+) - Chassis ground (-):

   (B77) No. 6 (+) - Chassis ground (-):

   Is there any voltage?

   Yes  Repair or replace the short circuit of the harness.

   No  Replace the A/C control panel. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>CONTROL PANEL>REMOVAL .