Ignition Control System: Wiring Diagram

Fig 1: Identifying Ignition Control System - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE CHART

Step	Check	Yes	No
1 CHECK IGNITION SYSTEM FOR SPARKS. Remove the plug cord cap from each spark plug. Install a new spark plug on plug cord cap. CAUTION: Do not remove the spark plug from engine. 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 the fuel pump system. <Ref. to FUEL PUMP CIRCUIT , Diagnostics For Engine Starting Failure .>	Go to step 2.
2 CHECK POWER SUPPLY CIRCUIT FOR IGNITION COIL AND IGNITOR ASSEMBLY. Turn the ignition switch to OFF. Disconnect the connector from the ignition coil and ignitor assembly. Turn the ignition switch to ON. Measure the power supply voltage between ignition coil and ignitor assembly connector and engine ground. Connector & terminal (E12) No. 2 (+) - Engine ground (-):	Is the voltage 10 V or more?	Go to step 3.	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between the ignition coil and ignitor assembly, and main relay connector Poor contact of coupling connector
3 CHECK HARNESS BETWEEN ECM AND IGNITION COIL AND IGNITOR ASSEMBLY. Turn the ignition switch to OFF. Disconnect the connectors from the ECM. Measure the resistance of harness between ECM and ignition coil and ignitor assembly connector. Connector & terminal (E12) No. 3 - (B137) No. 6: (E12) No. 3 - (B137) No. 26:	Is the resistance less than 5 Ω?	Go to step 4.	Repair the open circuit of harness between ECM and ignition coil and ignitor assembly connector.
4 CHECK IGNITION COIL AND IGNITOR ASSEMBLY. Remove the spark plug cords. Measure the resistance between spark plug cord contact portions to check secondary coil. Terminals No. 1 - No. 2: No. 3 - No. 4:	Is the resistance between 10 - 15 kΩ?	Go to step 5.	Replace the ignition coil and ignitor assembly. <Ref. to IGNITION COIL AND IGNITOR ASSEMBLY , Ignition Coil and Ignitor Assembly .>
5 CHECK INPUT SIGNAL FOR IGNITION COIL AND IGNITOR ASSEMBLY. Connect the connector to the Ignition coil and ignitor assembly. Check if voltage varies synchronously with engine speed when cranking, while monitoring voltage between ignition coil and ignitor assembly connector and engine ground. Connector & terminal (E12) No. 1 (+) - Engine ground (-): (E12) No. 4 (+) - Engine ground (-):	Does the voltage vary 10 V or more?	Go to step 6.	Replace the ignition coil and ignitor assembly. <Ref. to IGNITION COIL AND IGNITOR ASSEMBLY .> , Ignition Coil and Ignitor Assembly
6 CHECK HARNESS BETWEEN ECM AND IGNITION COIL AND IGNITOR ASSEMBLY CONNECTOR. Turn the ignition switch to OFF. Disconnect the connectors from the ECM. Disconnect the connector from the ignition coil and ignitor assembly. Measure the resistance of harness between ECM and ignition coil and ignitor assembly connector. Connector & terminal (B137) No. 18 - (E12) No. 1: (B137) No. 19 - (E12) No. 4:	Is the resistance less than 1 Ω?	Go to step 7.	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit in harness between ECM and ignition coil and ignitor assembly connector Poor contact of coupling connector
7 CHECK HARNESS BETWEEN ECM AND IGNITION COIL AND IGNITOR ASSEMBLY CONNECTOR. Measure the resistance of harness between ECM and engine ground. Connector & terminal: (B137) No. 18 - Engine ground: (B137) No. 19 - Engine ground:	Is the resistance 1 MΩ or more?	Go to step 8.	Repair short circuit of the harness to ground between ECM and ignition coil and ignitor assembly connector.
8 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.	Check the fuel pump circuit. <Ref. to FUEL PUMP CIRCUIT , Diagnostics For Engine Starting Failure .>