Wiring Diagram:

Fig 1: Control Module Power Supply And Ground Line - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

CONTROL MODULE POWER SUPPLY AND GROUND LINE - DIAGNOSIS STEP

Step	Check	Yes	No
1. CHECK MAIN RELAY. Turn the ignition switch to OFF. Remove the main relay. Connect the battery to main relay terminals No. 1 and No. 2. Measure the resistance between main relay terminals. Terminals No. 3 - No. 5: No. 4 - No. 6:	Is the measured value less than 10 Ω?	Go to step 2.	Replace the main relay.
2. CHECK GROUND CIRCUIT OF ECM. Disconnect the connector from ECM. Measure the resistance of harness between ECM and chassis ground. Connector & terminal (B134) No. 6 - Chassis ground: (B134) No. 7 - Chassis ground: (B134) No. 34 - Chassis ground: (B135) No. 1 - Chassis ground: (B135) No. 4 - Chassis ground: (B137) No. 1 - Chassis ground: (B137) No. 2 - Chassis ground:	Is the measured value less than 5 Ω?	Go to step 3.	Repair the open circuit in harness between ECM connector and engine grounding terminal.
3. CHECK INPUT VOLTAGE OF ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B135) No. 19 (+) - Chassis ground (-): (B137) No. 15 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Go to step 4.	Repair the open or ground short circuit of power supply circuit.
4. CHECK INPUT VOLTAGE OF MAIN RELAY. Measure the voltage between main relay connector and chassis ground. Connector & terminal (B47) No. 1 (+) - Chassis ground (-): (B47) No. 5 (+) - Chassis ground (-): (B47) No. 6 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Go to step 5.	Repair the open or ground short circuit in harness of power supply circuit.
5. CHECK INPUT VOLTAGE OF ECM. Connect the main relay connector. Turn the ignition switch to ON. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B135) No. 5 (+) - Chassis ground (-): (B135) No. 6 (+) - Chassis ground (-): (B137) No. 17 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Check the ignition control system. < Ref. to , IGNITION CONTROL SYSTEM, Diagnostics for Engine Starting Failure . >	Repair the open or ground short circuit in harness between ECM connector and main relay connector.