Impreza WRX 2.0L
- Remove and inspect all spark plugs. If spark plugs are okay, reinstall all spark plugs and go to next step. If spark plugs are not okay, replace as necessary.
- Check ignition system for spark. Remove plug wire from each spark plug. DO NOT remove spark plug from cylinder. Install new spark plug or spark plug tester to each plug wire. Make contact of thread portion of spark plug with engine. While opening throttle valve fully, crank engine to check that spark occurs at each cylinder. If spark occurs at each cylinder, check fuel pump system. See FUEL PUMP CIRCUIT TESTS under FUEL SYSTEMS. If spark does not occur at each cylinder, go to next step.
- Turn ignition off. Disconnect 3-pin electrical harness connector from ignition coil and ignitor assembly at each cylinder. Turn ignition on. Using a DVOM, measure power supply voltage of Red/Yellow wire between harness side of each ignition coil and ignitor assembly 3-pin electrical harness connector terminal No. 3 and good engine ground point. If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, repair open circuit in harness between identified ignition coil and ignitor assembly and ignition switch. Note that wire changes color to Green/Red at Brown 16-pin connector located at left front corner of engine compartment, in front of main fuse box. Also check for poor contact in all connectors between ignition coil and ignitor assemblies and ignition switch. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition off and leave 3-pin ignition coil and ignitor assembly electrical harness connectors disconnected. Using a DVOM, measure ground circuit resistance of Black/Yellow wire between harness side of each ignition coil and ignitor assembly 3-pin electrical harness connector terminal No. 2 and good engine ground point. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair open circuit in harness between identified ignition coil and ignitor assembly and engine ground point located at top left side of engine. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition off and leave 3-pin ignition coil and ignitor assembly electrical harness connectors disconnected. Locate ECM and disconnect 24-pin electrical harness connector B136. Using a DVOM, measure resistance of wire between specified terminal on harness side of ECM 24-pin electrical harness connector B136 and specified terminal on harness side of each ignition coil and ignitor assembly 3-pin electrical harness connector. See ECM-TO-IGNITION COIL & IGNITOR ASSEMBLY TEST POINTS (IMPREZA WRX 2.0L) table. If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, repair open circuit in harness between ECM and identified ignition coil and ignitor assembly. Also check for poor contact in all connectors between ECM and ignition coil and ignitor assemblies. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Leave ECM and ignition coil and ignitor assembly electrical harness connectors disconnected. Using a DVOM, measure resistance between specified terminal on harness side of ECM 24-pin electrical harness connector B136 and good chassis ground point. See ECM-TO-IGNITION COIL & IGNITOR ASSEMBLY TEST POINTS (IMPREZA WRX 2.0L) table. If resistance is greater than one megohm, go to next step. If resistance is not greater than one megohm, repair short circuit in harness between ECM and identified ignition coil and ignitor assembly. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Check for poor contact of terminals in connectors between ECM and ignition coil and ignitor assemblies. If poor contact exists in any connector, repair as required. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If poor contact does not exist, check fuel pump circuit. See FUEL PUMP CIRCUIT TESTS
under FUEL SYSTEMS.ECM-TO-IGNITION COIL & IGNITOR ASSEMBLY TEST POINTS (IMPREZA WRX 2.0L)
ECM Harness Connector & Terminal No. ECM Harness Connector Wire Color Cylinder No. (1) Ignition Coil & Ignitor Assembly Terminal No. 1 Wire Color 24-Pin B136 21 Yellow/Green 4 Yellow 22 Yellow/Red 3 White/Yellow 23 Yellow/Black 2 Blue/Yellow 24 Yellow 1 Green/Yellow (1) Wire changes color at Brown 16-pin connector located at left front corner of engine compartment in front of main fuse box.