Fuel Injector Circuit

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Check or repair only faulty parts.
Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

CHECK OPERATION OF EACH FUEL INJECTOR .
While cranking the engine, check each fuel injector emits operating sound. Use a sound scope or attach a screwdriver to the injector to listen to sounds for this check.

Does the fuel injector emit operating sound?

Yes : Check the fuel pressure. Ref. to MECHANICAL (H4DO)>FUEL PRESSURE .

No : Go to 2 .
CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (OPEN) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Move the A/C compressor aside so that it does not interfere with the work. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .
  NOTE: This procedure is required to disconnect the fuel injector #2 connector.
4. Disconnect the connector from fuel injector.
5. Measure the resistance of harness between ECM and fuel injector connector.
  Connector and terminal
  
  #1 (E53) No. 96 - (E101) No. 1:
  
  #1 (E53) No. 87 - (E101) No. 2:
  
  #2 (E53) No. 95 - (E102) No. 1:
  
  #2 (E53) No. 86 - (E102) No. 2:
  
  #3 (E53) No. 93 - (E103) No. 1:
  
  #3 (E53) No. 84 - (E103) No. 2:
  
  #4 (E53) No. 94 - (E104) No. 1:
  
  #4 (E53) No. 85 - (E104) No. 2:
  
  Is the resistance less than 1 Ω?
  
  Yes : Go to 3 .
  
  No : Repair the following item.
  - Open circuit in harness between ECM and fuel injector connector
  - Poor contact of coupling connector
CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR (SHORT TO GROUND) .
Measure the resistance between fuel injector connector and engine ground.

Connector and terminal

#1 (E101) No. 1 - Engine ground:

#1 (E101) No. 2 - Engine ground:

#2 (E102) No. 1 - Engine ground:

#2 (E102) No. 2 - Engine ground:

#3 (E103) No. 1 - Engine ground:

#3 (E103) No. 2 - Engine ground:

#4 (E104) No. 1 - Engine ground:

#4 (E104) No. 2 - Engine ground:

Is the resistance 1 MΩ or more?

Yes : Go to 4 .

No : Repair the short circuit to ground in harness between ECM and fuel injector connector.
CHECK EACH FUEL INJECTOR .
Check each fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .

Is the check result OK?

Yes : Repair the poor contact of ECM connector.

No : Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .