S90 & V90
- Determine if fault is fuel or ignition. If fault is fuel related, go to FUEL SYSTEM . If fault is ignition, go to next step.
- Disconnect one spark plug connector. Check for spark. If spark is present, go to step 8). If spark is not present, install scan tool to Data Link Connector (DLC) and check RPM signal while cranking engine. If engine speed is zero RPM, check RPM sensor circuit. If circuit is okay, replace RPM sensor. If engine speed is 100-300 RPM, go to next step.
- Ensure ignition is off. Remove fuel pump relay from position No. 2 in relay/fuse box on left side of instrument panel. Connect jumper wire between relay base terminals No. 1 and 5. See Figure. Turn ignition on. Connect voltmeter between ground and cylinder No. 1 test terminal at rear of engine. See Fig 1. If battery voltage is not present, go to next step. If battery voltage is present, check Ignition Discharge Module (IDM) ground terminal No. 4 for poor connection. See Fig 2.
- Ensure ignition is off. Access fuse/relay box in left side of engine compartment. Remove ignition relay located in fuse/relay box position "J". See Figure. Connect ohmmeter between relay base terminal No. 4 and ground. See Fig 3. If about zero ohms are present, go to next step. If about zero ohms are not present, check ignition relay terminals for poor terminal contact. Repair as necessary. Repeat resistance check. If resistance is now to specification, source of fault was poor contact in relay ground. If resistance is not to specification, check for an open circuit in wiring between ignition relay terminal No. 4 and terminal block in fuse/relay block.
- Turn ignition on. Ensure ignition relay is disconnected. Connect voltmeter between relay base terminals No. 1 and 4. See Fig 3. If battery voltage is present, go to next step. If battery voltage is not present, check voltage supply to fuse No. 7. If voltage supply is okay, check for open circuit in wiring between fuse No. 7 and ignition relay terminal No. 1. If voltage supply is not okay, check for open circuit in wiring between fuse No. 7 and main relay terminal No. 3. See appropriate wiring diagram in WIRING DIAGRAMS article.
- Ensure ignition is on. Ensure ignition relay is disconnected. Connect jumper wire between relay base terminals No. 1 and 5. See Fig 3. Check voltage between relay base terminals No. 2 and ground. If battery voltage is present, go to next step. If battery voltage is not present, check wiring between ignition relay terminal No. 2 and fuel pump relay terminal No. 5. Fuel pump relay is located in position No. 2 of fuse/relay box on left side of instrument panel.
- Turn ignition on. Ensure ignition relay is disconnected. Connect jumper wire between ignition relay base terminals No. 1 and 5. Reconnect ignition relay far enough to allow voltage readings to be taken on relay pins. Check voltage supply to ignition relay. If battery voltage is present, check for open circuit in wiring between ignition relay terminal No. 3 and ignition coil(s) terminal No. 2. See appropriate wiring diagram in WIRING DIAGRAMS article. If battery voltage is not present, replace ignition relay.
- If spark was present in step 2), replace all spark plugs. Attempt to start engine. If engine starts, system is okay. If engine still does not start, go to next step.
- Connect scan tool. Turn ignition on. Crank starter motor. Read off engine load signal. If reading is about 0.4-0.6 volt, go to next step. If reading is not about 0.4-0.6 volt, check Mass Airflow (MAF) sensor. See K - SENSOR OPERATING RANGE CHARTS article.
- Turn ignition on. Using scan tool, go into scrolling values. Connect Multimeter (999 6525
) with Temperature Box (999 5281
) and Engine Coolant Temperature (ECT) Sensor (999 5282
). Using pliers, squeeze hose between radiator and thermostat, bend down carefully, and remove it from thermostat housing. Put ECT sensor into thermostat housing. Reinstall hose. Ensure sensor reaches all the way down to thermostat. Read coolant temperature on multimeter.WARNING: Coolant may be very hot.
- Using scan tool, read off coolant temperature. Reinstall hose. If scan tool displays correct coolant temperature, go to next step. If scan tool does not display correct coolant temperature, check ECT sensor. See K - SENSOR OPERATING RANGE CHARTS article.
- Turn ignition off. If not done previously, check fuel and residual pressure. Go to FUEL PRESSURE under FUEL SYSTEM. If fuel pressure is okay, go to next step.
- Connect breakout box to ECM. See Fig 4. Check all signals to and from ECM. See PIN VOLTAGE CHART S article. Repair circuits as necessary. If circuits are okay, replace ECM.