ECM Power Supply & Ground Tests
- Check Main Relay
Turn ignition off. Remove main relay, located at left kick panel. Connect battery voltage to main relay terminals No. 1 and 2. Check resistance between main relay terminals No. 3 and 5, and terminals No. 4 and 6. See Fig 1 . Resistance should be less than 10 ohms in both tests. If resistance is as specified, go to next step. If resistance is not as specified, replace main relay. - Check ECM Power Supply Circuit
Reconnect main relay. Disconnect ECM harness connector. Turn ignition on. On Legacy 2.2L, using DVOM, check voltage between specified ECM connector terminals. See ECM HARNESS CONNECTOR & TERMINAL IDENTIFICATION (LEGACY 2.2L) table. On Legacy 2.5L and Outback 2.5L, using DVOM in voltmeter mode, connect DVOM negative lead to ECM harness connector No. 19. In sequence, connect DVOM positive lead to ECM harness connector terminals No. 1, 2 and 39. See Fig 3 . On all models except Legacy, using DVOM, check voltage between chassis ground and ECM connector B135 (28-pin), terminal No. 7 and ECM connector B136 (30-pin), terminals No. 1, 2, 3, 7 and 9. See Fig 2 . On all models, voltage reading on each listed terminal should be greater than 10 volts. If voltage reading is as specified, go to next step. If voltage reading is not as specified, check and repair circuit between main relay and ECM harness connectors. See appropriate wiring diagram in WIRING DIAGRAMS article. - Check ECM Ground Circuit
Turn ignition off. Disconnect ECM harness connector. On Legacy 2.5L and Outback 2.5L, using DVOM, check resistance between chassis ground and in sequence, ECM harness connector terminals No. 17, 18, 19, 20, 42, 46, 69, 94 and 95. See Fig 3 . On all models except Legacy 2.5L and Outback 2.5L, using DVOM, check resistance between chassis ground and in sequence, ECM connector B134 (35-pin), terminals No. 7, 8, 27, 34 and 35 and ECM connector B136 (30-pin), terminals No. 21 and 22. See Fig 2 . On all models, resistance on each listed terminal should be less than 5 ohms. If resistance is as specified, see IGNITION CONTROL SYSTEM TESTS . If resistance is not as specified, check affected circuit between ground and ECM harness connector or check for poor terminal contact in harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article.
ECM HARNESS CONNECTOR & TERMINAL IDENTIFICATION (LEGACY 2.2L)
| ECM 35-Pin Connector Terminal No. | ECM 30-Pin Connector Terminal No. |
|---|---|
| 1 | 8 |
| 8 | 2 |
| 8 | 9 |