Engine Controls - Basic Testing: Other Subaru Outback BG

Compression

Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions.

Exhaust System Backpressure

1. The exhaust system can be checked with a vacuum or pressure gauge. Remove HO2S sensor or air injection check valve (if equipped).
2. Connect a 1-10 psi pressure gauge and operate engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.
3. If a vacuum gauge is used, connect vacuum gauge to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold it steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.

FUEL PRESSURE

Basic diagnosis of fuel system should begin by determining fuel system pressure. If fuel pump is inoperative, see appropriate test under FUEL PUMP CIRCUIT TESTS .

Relieving Fuel Pressure

1. Disconnect fuel pump connector. Crank engine for at least 5 seconds. If engine starts, let it run until it stops. Disconnect fuel hose at pressure regulator and install fuel pressure gauge using "T" connector.
2. Start engine and check fuel pressure at idle. See the «REGULATED FUEL PRESSURE»(ref-26247-S14508919482001010800000) table. Verify fuel pressure increases as engine speed increases.

REGULATED FUEL PRESSURE

IGNITION CHECKS

Note. Also see appropriate test under IGNITION CONTROL SYSTEM TESTS.

SPARK

Check for spark at spark plug wires using a spark tester. Check resistance of each spark plug wire. Replace wire if resistance is not within specification. See HIGH TENSION WIRE RESISTANCE table.

HIGH TENSION WIRE RESISTANCE

IGNITION COIL RESISTANCE

1. Disconnect 3-wire connector from ignition coil assembly. Using an ohmmeter, check primary resistance between terminals No. 1 and 2 for one coil. (Scheme 1)
2. Check primary resistance between terminals No. 2 and 3 for remaining coil. Resistance should be as specified. Refer to the «IGNITION COIL RESISTANCE»(ref-26247-S16082388892001010800000) table. If resistance is not as specified for each coil, replace ignition coil assembly.
3. To test secondary resistance, connect ohmmeter between ignition coil secondary terminals No. 1 and 2, and terminals No. 3 and 4.
4. Repeat test for other coils. If resistance of each coil is not as specified, replace ignition coil assembly.

Scheme 1

IGNITION COIL RESISTANCE - OHMS @ 68°F (20°C)

CRANKSHAFT POSITION SENSOR SIGNALS

Note. For crankshaft position sensor signal testing, see appropriate TESTS W/CODES article.

IDLE SPEED & IGNITION TIMING

Verify idle speed and ignition timing are set to specification. Refer to the IDLE SPEED SPECIFICATIONS table and the IGNITION TIMING table in this article. For adjustment procedures, see the ADJUSTMENTS article.

IDLE SPEED SPECIFICATIONS

IGNITION TIMING (Degrees BTDC @ RPM)

ECM POWER SUPPLY & GROUND TESTS

1. Check Main Relay - Turn ignition off and remove main relay. 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 appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. 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.
2. Check ECM Power Supply Circuit - Reconnect main relay and disconnect ECM harness connector. Turn ignition on. Using DVOM, check voltage between the following ECM harness connector terminals: Terminals No. 1 and 19 Terminals No. 2 and 19 Terminals No. 19 and 39 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 connector. See wiring diagram in appropriate «WIRING DIAGRAMS»(ref-26255) article.
3. Check ECM Ground Circuit - Turn ignition off. Disconnect ECM harness connector. Using DVOM, check resistance between chassis ground and the following ECM harness connector terminals: Terminal No. 17 Terminal No. 18 Terminal No. 19 Terminal No. 20 Terminal No. 42 Terminal No. 46 Terminal No. 69 Terminal No. 94 Terminal No. 95 Resistance on each listed terminal should be less than 5 ohms. If resistance is as specified, see «IGNITION CONTROL SYSTEM TESTS»(ref-26247-S35290663612001010800000) . If resistance is not as specified, check affected ground circuit between ECM harness connector or check for poor terminal contact in harness connector. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article.

IGNITION CONTROL SYSTEM TESTS

1. Check Ignition System For Proper Spark - Remove injector sub-harness and spark plug wire cap from each spark plug. Install a known-good spark plug to spark plug wire and position spark plug so it is grounded to engine. Crank engine. If a spark does not occur at each spark plug, reconnect injector sub-harness and spark plug wires and go to next step. If a spark does occur at each spark plug, see «FUEL PUMP CIRCUIT TESTS»(ref-26247-S29319441852001010800000) .
2. Check Voltage At Ignition Coil Positive Terminal - Turn ignition on. Ensure there is at least 10 volts between ignition coil 3-pin harness connector terminal No. 2 and ground. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. If voltage is as specified, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
3. Check Ignition Coil - Remove ignition coil connector and remove ignition coil. Check resistance of ignition coil primary and secondary windings. See the «IGNITION COIL RESISTANCE»(ref-26247-S16082388892001010800000) table. If resistance is as specified, go to next step. If resistance is not as specified, replace ignition coil.
4. Check Ignitor Output Signal - Connect all connectors. Check voltage between ignitor output harness connector terminal No. 1 and ground, and terminal No. 2 and ground, while cranking engine. Voltage reading should be at least .1 volt. If voltage reading is as specified, go to next step. If voltage reading is not as specified, replace ignitor.
5. Check Harness Between ECM & Ignitor - Turn ignition off. Disconnect ECM and ignitor harness connectors. Ensure there is zero ohms between ECM harness connector terminal No. 9 and ignitor terminal No. 2, ECM harness connector terminal No. 10 and ignitor terminal No. 1, ECM harness connector terminal No. 15 and ignitor terminal No. 3 and ground. Ensure there is no continuity between ignitor terminal No. 1 and ground, and between ignitor terminal No. 2 and ground. If resistance is as specified, inspect ECM connector and repair as necessary. If ECM connector is okay, replace ECM. If resistance is not as specified, repair harness or connectors as necessary.

FUEL PUMP CIRCUIT TESTS

1. Check Fuel Pump Operation In D-Check Mode - Connect test mode connector and turn ignition on. Ensure fuel pump operates for 2 seconds after turning ignition on. If fuel pump operates for 2 seconds, check fuel injector circuit. See «FUEL INJECTOR CIRCUIT TESTS»(ref-26247-S02030865002001010800000). If fuel pump does not operate, go to next step.
2. Check Fuel Pump Relay - Disconnect fuel pump relay connector and remove fuel pump relay from bracket. Ensure there is 70 ohms of resistance between fuel pump relay terminals No. 1 and 3. (Scheme 2) Replace fuel pump relay if resistance is not as specified. If resistance is okay, connect positive battery lead to terminal No. 1 and negative lead to terminal No. 3. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. If fuel pump relay does not click, replace it. If fuel pump relay clicks, verify zero ohms resistance between terminals No. 2 and 4. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump relay.
3. Check Voltage Between Fuel Pump Relay & Ground - Turn ignition off. Remove fuel pump relay without disconnecting connector. Ensure there is at least 10 volts between fuel pump relay connector terminal No. 1 and ground. If at least 10 volts are present, go to next step. If at least 10 volts are not present, repair harness or connector.
4. Check Voltage Between ECM & Ground - Turn ignition on. Check voltage between ECM 26-pin connector terminal No. 23 and ground. Ensure there is at least 10 volts when ignition is on and zero volts while cranking engine. If voltage reading is as specified, go to next step. If voltage reading is not as specified, repair faulty connector or ground circuit. If connector and ground are okay, replace ECM.
5. Check Fuel Pump Terminal Voltage - Remove fuel pump access cover located in trunk area and remove fuel pump connector. Ensure there is at least 10 volts between 5-pin fuel pump connector terminal No. 1 and ground. If at least 10 volts are present, go to next step. If at least 10 volts are not present, repair harness or connectors between fuel pump and fuel pump relay as necessary.
6. Check Fuel Pump Operation - Disconnect fuel pump connector. Connect positive battery lead to terminal No. 1 and negative lead to terminal No. 3. If fuel pump operates, repair fuel pump grounding circuit. If fuel pump does not operate, replace fuel pump.

Scheme 2

FUEL INJECTOR CIRCUIT TESTS

1. Check Fuel Injector Operation - Using a stethoscope, ensure that injector operating sound (clicking) is present while engine is cranking. If operating sounds are not heard, go to next step. If operating sounds are heard, verify fuel pressure. See «FUEL PRESSURE»(ref-26247-S20323641932001010800000) under FUEL SYSTEM.
2. Check Fuel Injector Power Circuit - Turn ignition off. Disconnect each fuel injector connector. Ensure there is at least 10 volts between each injector terminal No. 2 and ground. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-26255) article. If voltage is as specified, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
3. Check Fuel Injector Resistance - Disconnect each injector connector. Ensure there is 11-12 ohms resistance between injector terminals No. 1 and 2. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel injector(s).
4. Check Voltage At Each ECM Terminal - Ensure there are at least 10 volts between ground and ECM 26-pin harness connector terminals No. 11, No. 12, No. 13, and No. 26. If voltage is as specified, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
5. Check Harness Connector Between ECM & Ground - Turn ignition off. Disconnect ECM 26-pin connector. Ensure there is zero ohms resistance between connector terminal No. 24 and ground, and between terminal No. 25 and ground. If specified resistance is not present, repair harness or connectors as necessary. If specified resistance is present, inspect and repair ECM connector. If ECM connector is okay, replace ECM.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate TESTS W/CODES article. If no hard codes are found in TESTS W/CODES , go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.