2005 Subaru Forester XT, AutomaticFACTORY OEM SERVICE PROCEDURE

Ignition Control System

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to , PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM: 

Fig 1: Wiring Diagram - Ignition Control System
G03806956Courtesy of SUBARU OF AMERICA, INC.
IGNITION CONTROL SYSTEM PROBLEM SYMPTOMS

Step Check Yes No
1 CHECK SPARK PLUG CONDITION. 
  1. Remove the spark plug. < Ref. to REMOVAL , Spark Plug. >
  2. Check the spark plug condition. < Ref. to INSPECTION , Spark Plug. >
 Is the spark plug's status OK? Go to step 2  . Replace the spark plug.
2 CHECK IGNITION SYSTEM FOR SPARKS. 
  1. Connect the spark plug to ignition coil.
  2. Release the fuel pressure. < Ref. to RELEASING OF FUEL PRESSURE , Procedure, Fuel. >
  3. Contact the spark plug's thread portion on engine.
  4. While opening the throttle valve fully, crank engine to check that spark occurs at each cylinder.
 Does spark occur at each cylinder? Check the fuel pump system.
< Ref. to , FUEL PUMP CIRCUIT , Diagnostics for Engine Starting Failure. >		 Go to step 3  .
3 CHECK POWER SUPPLY CIRCUIT FOR IGNITION COIL & IGNITOR ASSEMBLY. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ignition coil & ignitor assembly.
  3. Turn the ignition switch to ON.
  4. Measure the power supply voltage between ignition coil & ignitor assembly connector and engine ground.

Connector & terminal 
(E31) No. 3 (+) - Engine ground (-): 
(E32) No. 3 (+) - Engine ground (-): 
(E33) No. 3 (+) - Engine ground (-): 
(E34) No. 3 (+) - Engine ground (-): 		 Is the voltage more than 10 V? Go to step 4  . Repair the harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between ignition coil & ignitor assembly, and ignition switch connector
  • Poor contact in coupling connectors
4 CHECK HARNESS OF IGNITION COIL & IGNITOR ASSEMBLY GROUND CIRCUIT. 
  1. Turn the ignition switch to OFF.
  2. Measure the resistance between ignition coil & ignitor assembly connector and engine ground.

Connector & terminal 
(E31) No. 2 - Engine ground: 
(E32) No. 2 - Engine ground: 
(E33) No. 2 - Engine ground: 
(E34) No. 2 - Engine ground: 		 Is the resistance less than 5 Ω? Go to step 5. Repair the harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between ignition coil & ignitor assembly connector and engine grounding terminal
5 CHECK HARNESS BETWEEN ECM AND IGNITION COIL & IGNITOR ASSEMBLY CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ECM.
  3. Disconnect the connector from ignition coil & ignitor assembly.
  4. Measure the resistance of harness between ECM and ignition coil & ignitor assembly connector.

Connector & terminal 
(B135) No. 15 - (E34) No. 1: 
(B135)NO. 16 - (E33)No. 1: 
(B135)No. 17-(E32)No. 1: 
(B135)No. 18 - (E31)No. 1: 		 Is the resistance less than 1 Ω? Go to step 6  . Repair the harness and connector.
NOTE: In this case, repair the following:
  • Open circuit in harness between ECM and ignition coil & ignitor assembly connector
  • Poor contact in coupling connector
6 CHECK HARNESS BETWEEN ECM AND IGNITION COIL & IGNITOR ASSEMBLY CONNECTOR. 
Measure the resistance of harness between ECM and engine ground.
Connector & terminal: 
(B135) No. 15 - Engine ground: 
(B135) No. 16 - Engine ground: 
(B135) No. 17 - Engine ground: 
(B135) No. 18 - Engine ground: 		 Is the resistance more than 1 MΩ? Go to step 7  . Repair the ground short circuit in harness between ECM and ignition coil & ignitor assembly connector.
7 CHECK POOR CONTACT. 
Check poor contact in ECM connector.		 Is there poor contact in ECM connector? Repair the poor contact in ECM connector. Check the fuel pump circuit.
< Ref. to , FUEL PUMP CIRCUIT , Diagnostics for Engine Starting Failure. >
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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