LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2006 >> Forester XT Limited, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Engine (Diagnostics) (H4DOTC) >> Diagnostics for Engine Starting Failure >> Ignition Control System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Ignition Control System

CAUTION: After repairing or replacing the defective part, carry out the Clear Memory Mode <Ref. to OPERATION , CLEAR MEMORY MODE. > and Inspection Mode <Ref. to PROCEDURE , INSPECTION MODE. >.

WIRING DIAGRAM: 

Fig 1: Identifying Ignition Control System - Wiring Diagram
G05002037Courtesy of SUBARU OF AMERICA, INC.
TROUBLESHOOTING CHART

Step Check Yes No
1 CHECK SPARK PLUG CONDITION. 
  1. Remove the spark plug. <Ref. to INSTALLATION , Spark Plug. >
  2. Check the spark plug condition. <Ref. to INSPECTION , Spark Plug. >
Is the spark plug condition 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. Touch the threaded portion of the spark plug to the engine.
  4. While opening the throttle valve fully, crank the engine to check that spark occurs at each cylinder.
Does spark occur at each cylinder? Check 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 item:
  • Open circuit of harness between the ignition coil & ignitor assembly, and ignition switch connector
  • Poor contact of coupling connector
4 CHECK HARNESS OF IGNITION COIL & IGNITOR ASSEMBLY GROUND CIRCUIT. 
  1. Turn the ignition switch to OFF.
  2. Measure the resistance between the 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 item:
  • Open circuit of harness between ignition coil and ignitor assembly connector & engine grounding terminal
5 CHECK HARNESS BETWEEN ECM AND IGNITION COIL & IGNITOR ASSEMBLY CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connectors 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 

    (B137) No. 21 - (E34) No. 1: 

    (B137) No. 20 - (E33) No. 1: 

    (B137) No. 19 - (E32) No. 1: 

    (B137) 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 item:
  • Open circuit of harness between ECM and ignition coil & ignitor assembly connector
  • Poor contact of 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 

(B137) No. 21 - Engine ground: 

(B137) No. 20 - Engine ground: 

(B137) No. 19 - Engine ground: 

(B137) No. 18 - Engine ground: 

Is the resistance more than 1 MΩ? Go to step 7. Repair the ground short circuit of harness between ECM and ignition coil & ignitor assembly connector.
7 CHECK POOR CONTACT. 
Check poor contact of ECM connector.
Is there poor contact in ECM connector? Repair poor contact in ECM connector. Check fuel pump circuit. <Ref. to FUEL PUMP CIRCUIT , DIAGNOSTICS FOR ENGINE STARTING FAILURE. >