Ignition Control System: Wiring Diagram

Fig 1: Ignition Control System - Wiring Schematics

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSIS PROCEDURE CHART

Step	Check	Yes	No
1 CHECK SPARK PLUG CONDITION . Remove the spark plug. Refer to REMOVAL , Spark Plug. Check the spark plug condition. Refer to INSPECTION , Spark Plug.	Is the spark plug condition normal?	Go to step 2 .	Replace the spark plug. Refer to SPARK PLUG .
2 CHECK IGNITION SYSTEM FOR SPARKS . Connect the spark plug to ignition coil. Release the fuel pressure. Refer to RELEASING OF FUEL PRESSURE , PROCEDURE, Fuel. Contact the spark plug thread portion to engine. 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. Refer to FUEL PUMP CIRCUIT , Diagnostics for Engine Starting Failure.	Go to step 3 .
3 CHECK POWER SUPPLY CIRCUIT FOR IGNITION COIL . Turn the ignition switch to OFF. Disconnect the connector from ignition coil. Turn the ignition switch to ON. Measure the power supply voltage between ignition coil 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 10 V or more?	Go to step 4 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit in harness between ignition coil connector and ignition switch connector Poor contact of coupling connector
4 CHECK HARNESS OF IGNITION COIL GROUND CIRCUIT . Turn the ignition switch to OFF. Measure the resistance between ECM and ignition coil connector. Connector & terminal (E31) No. 2 - (B137) No. 6: (E32) No. 2 - (B137) No. 6: (E33) No. 2 - (B137) No. 6: (E34) No. 2 - (B137) No. 6: (E31) No. 2 - (B137) No. 26: (E32) No. 2 - (B137) No. 26: (E33) No. 2 - (B137) No. 26: (E34) No. 2 - (B137) No. 26:	Is the resistance less than 1 Ω?	Go to step 5 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between the ECM and ignition coil connector Poor contact of coupling connector
5 CHECK HARNESS BETWEEN ECM AND IGNITION COIL CONNECTOR . Turn the ignition switch to OFF. Disconnect the connector from ECM and ignition coil. Measure the resistance of harness between the ECM and ignition coil connector. Connector & terminal (B137) No. 18 - (E31) No. 1: (B137) No. 19 - (E32) No. 1: (B137) No. 20 - (E33) No. 1: (B137) No. 21 - (E34) 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 the ECM and ignition coil connector Poor contact of coupling connector
6 CHECK HARNESS BETWEEN ECM AND IGNITION COIL CONNECTOR . Measure the resistance of harness between ECM and engine ground. Connector & terminal (B137) No. 18 - Engine ground: (B137) No. 19 - Engine ground: (B137) No. 20 - Engine ground: (B137) No. 21 - Engine ground:	Is the resistance 1 MΩ or more?	Go to step 7 .	Repair the ground short circuit of harness between the ECM and ignition coil connector.
7 CHECK POOR CONTACT . Check for poor contact of the ECM connector.	Is there poor contact in ECM connector?	Repair poor contact of the ECM connector.	Replace the ignition coil. Refer to IGNITION COIL .