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HOMESERVICE MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 48 (ENGINE CONTROLS - BASIC TESTING - V6)IGNITION CHECKSDISTRIBUTOR IGNITION (DI) SYSTEMSPARK CHECK
1991 Mercury Tracer Base, 4D Sedan, Automatic

Spark Check

1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Spark Check
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 1994 Mercury Topaz, 1994 Mercury Sable, 1994 Mercury Cougar, 1994 Lincoln Continental, and 1994 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the DI system (formerly Thick Film Ignition-IV (TFI-IV) system) for fault codes and repair if necessary. Proceed to QUICK TEST in appropriate TESTS W/CODES article listed below. If no fault codes are retrieved, check ignition system wiring harness connectors for damage, corrosion and tight fit. See Fig 1 or Fig 2.
  2. If no fault codes are retrieved and vehicle starts, problem is intermittent, go to appropriate TESTS W/O CODES article listed 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.
  3. If spark is present, go to step 4). If no spark is present, remove distributor cap and crank engine to ensure distributor rotates. If okay, check resistance of coil secondary wire. Resistance should be less than 7000 ohms per foot. Service coil wire if necessary and retest. If spark is not present, see appropriate SYSTEM/COMPONENT TESTS article as listed below or the appropriate TESTS W/O CODES article also listed below.
  4. On all models, 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 TESTS W/O CODES article listed above.
Fig 1: DI System Electrical Diagram (3.0L)
G93H39492Courtesy of FORD MOTOR CO.
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.