Engine Controls - System & Component Testing: Other Subaru Forester SG

Ground Circuits

1. Turn ignition off. Using ohmmeter connected to ground, backprobe each ECM ground terminal. For ECM ground terminal identification, see appropriate pin voltage chart in «PIN VOLTAGE CHARTS»(ref-157574) article. Resistance should be zero ohms. If resistance is not close to zero ohms, repair open to ground.
2. Start engine. Using voltmeter connected to ground, backprobe each ground terminal. Voltage should be less than one volt. If voltage is more than one volt, check for open, corrosion, or loose connection on ground lead.

Power Circuits (Ignition Off)

Turn ignition off. Check for battery voltage between ECM power terminals and ground. For ECM power terminal identification, see appropriate pin voltage chart in PIN VOLTAGE CHARTS article. If battery voltage does not exist, check fuse or fusible link. Fuses are located under instrument panel. Auxiliary fuse panel is located in engine compartment on all models Fusible links are in engine compartment. If fuse and fusible link are okay, check for an open in wire between fuse/fusible link and ECM. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

Power Circuits (Ignition On)

Turn ignition on. Check for battery voltage between ECM power terminals and ground. For ECM power terminal identification, see appropriate pin voltage chart in PIN VOLTAGE CHARTS article. If battery voltage does not exist, check fuse. If fuse is okay, check for an open in wire or a defective ignition switch. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

Power Circuits (Cranking)

1. Using voltmeter, backprobe ECM connector crank signal terminal. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Hold ignition switch in START position. Battery voltage should exist between ECM terminal and ground only when ignition switch is in START position.
2. If battery voltage does not exist, check fusible link. Fusible links are in engine compartment. If fusible link is okay, check for open wire between fusible link and ECM terminal or for defective ignition switch.

A/C SWITCH

Test switch and circuits as necessary. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

CAMSHAFT POSITION (CMP) SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

CRANKSHAFT POSITION (CKP) SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

FUEL LEVEL SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

FUEL TEMPERATURE SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

INTAKE MANIFOLD PRESSURE SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

INTAKE AIR TEMPERATURE (IAT) SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

KNOCK SENSOR (KS)

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

HEATED OXYGEN SENSOR (HO2S)

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

NEUTRAL POSITION (NP) SWITCH

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

PRESSURE SENSOR

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

THROTTLE POSITION (TP) SENSOR

For adjustments, see ON-VEHICLE ADJUSTMENTS article. For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

VEHICLE SPEED SENSOR (VSS)

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

Cooling Fan Relay

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

Fuel Pump Relay

For testing procedures, see BASIC DIAGNOSTIC PROCEDURES article.

Main Relay

For testing procedures, see ENGINE CONTROL MODULE POWER SUPPLY & GROUND CIRCUITS in BASIC DIAGNOSTIC PROCEDURES article.

EGR Solenoid Valve

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

Purge Control Solenoid Valve

See FUEL EVAPORATIVE SYSTEM (EVAP) under EMISSION SYSTEMS & SUB-SYSTEMS.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES article.

Feedback System

Manufacturer recommends performing complete inspection of self-diagnostic system. This includes checking mechanical condition of engine, available fuel to injectors, and ignition. Repair or replace components as required, and test drive vehicle.

Fuel Injector(s)

1. Start and idle engine. Listen for clicking sound coming from each injector. If operating noise is not heard, check wiring connector, injector resistance, and injection signal from computer.
2. Turn ignition off. Unplug connector from each injector. Check injector resistance. Resistance should be 5-20 ohms. If resistance is not to specification, replace injector.

IDLE AIR CONTROL SOLENOID VALVE

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

IGNITION SYSTEM

Note. For basic ignition checks (coil and wires), see BASIC DIAGNOSTIC PROCEDURES article. For camshaft and crankshaft position sensor testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

Knock Sensor

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

FUEL EVAPORATIVE SYSTEM (EVAP)

Charcoal Canister

Inspect for visual damage. For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

EVAP Fuel Tank Pressure Control Solenoid

For testing procedures, see appropriate DTC in appropriate SELF-DIAGNOSTICS article.

Check self-diagnostic system for any DTCs. See appropriate DTC in appropriate SELF-DIAGNOSTICS article. Check valve winding for short to ground. Apply battery voltage to valve terminals. Verify passage opens and closes as voltage is applied and removed. Replace valve if winding is shorted, or if operation is not as specified.

POSITIVE CRANKCASE VENTILATION (PCV)

With engine idling, disconnect ventilation hose from PCV valve. If hissing noise and strong vacuum are not present at hose end, check hose and hose connections for leaks and obstructions. Repair or replace as necessary. Connect hose to PCV valve. Remove PCV valve from intake manifold. Place finger over PCV valve. Vacuum should be present. Remove finger from PCV valve. Valve should snap back.