Spark Output Check
- Check for trouble codes stored in PCM and repair if necessary. See QUICK TEST in appropriate article in the ENGINE PERFORMANCE section. If no trouble codes are retrieved, check ignition system wiring harness connectors for damage, corrosion and tight fit.
- If no fault codes are retrieved and vehicle will start, go to appropriate article in the ENGINE PERFORMANCE section (see below). If no fault codes are retrieved and vehicle is a no-start, connect a high-output spark tester between ignition coil wire and engine ground. Check for spark at coil wire while cranking engine. A consistent Blue spark should be present.
- If spark is present, go to step 4). If no spark is present, remove distributor cap and crank engine to ensure distributor rotor rotates. If okay, check resistance of coil secondary wire. Resistance should be less than 7000 ohms per foot. Service coil wire as necessary and retest. If spark is not present, go to IGNITION SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (4.0L)
article (for Aerostar and Explorer only). For additional testing information for Ranger, see TESTS W/CODES - EEC-V (4.0L)
.
- If a consistent Blue spark is present at coil wire during cranking, inspect distributor cap and rotor for cracks or carbon tracking. Service as necessary and test spark output at spark plugs. If spark is present at spark plugs and engine will not start, go to appropriate article in the ENGINE PERFORMANCE section: