DTC P04C1: Fuel Fill Door Unlock Control Circuit Low: Notes

1. - 

DTC detecting condition:  Immediately at fault recognition

Trouble symptom: 

• Fuel lid does not open. (At the time of open circuit)
• Fuel lid opens automatically. (At the time of short circuit to ground)

Wiring diagram:  Engine Electrical System Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK HARNESS BETWEEN ECM AND M/B (FUEL FLAP RELAY) (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Remove the fuel flap relay.
   3. Disconnect the ECM connector.
   4. Measure the resistance of harness between ECM connector and M/B (fuel flap relay) terminal.

      Connector & terminal 

      (B134) No. 34 - No. 4:

      Is the resistance less than 1 Ω?

      Yes:  Go to  2.

      No:  Repair the open circuit of harness between ECM connector and M/B (fuel flap relay) terminal.

2. CHECK HARNESS BETWEEN ECM AND M/B (FUEL FLAP RELAY) (SHORT TO GROUND)  .

   Measure the resistance between the ECM connector and engine ground.

   Connector & terminal 

   (B134) No. 34 - Engine ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  3.

   No:  Repair the short circuit to ground in harness between ECM connector and M/B (fuel flap relay) connector.

3. CHECK INPUT VOLTAGE OF FUEL FLAP RELAY  .
   1. Turn the ignition switch to ON.
   2. Measure the voltage between M/B (fuel flap relay) terminal and engine ground.

      Connector & terminal 

      No. 2 (+) - Engine ground (-):

      Is the voltage 10 V or more?

      Yes:  Go to  4.

      No:  Repair the open or ground short in the harness of power supply circuit.

4. CHECK FUEL FLAP RELAY  .

   Check the fuel flap relay. Ref. to SECURITY AND LOCKS>RELAY AND FUSE>INSPECTION>CHECK RELAY .

   Is the check result OK?

   Yes:  Repair the poor contact of ECM connector.

   No:  Replace the fuel flap relay. Ref. to SECURITY AND LOCKS>RELAY AND FUSE>LOCATION .