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Home >> Ford >> 1991 >> Probe GT, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> Ignition Checks >> Thick Film Ignition IV (TFI-IV) System >> Spark Output Check
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Spark Output Check

  1. 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 and should make a snapping noise as it jumps spark tester. If spark is present, go to step 3). If no spark is present, go to next step.
  2. 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 as necessary and retest. If spark is not present, go to step 4).
  3. 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 plug wire. If spark is now present at spark plugs and engine will not start, go to DIAGNOSTIC ROUTINE 201 (CRANKS NORMALLY BUT WON'T START) in the TESTS W/O CODES article in this section.
  4. With ignition off, disconnect SPOUT connector at distributor. Connect a 12-volt test light to TFI module side of SPOUT connector. See Fig 1 -Fig 3 . Crank engine. If light blinks, the PIP sensor and TFI module are okay, use the appropriate coil testing procedure in the SYSTEM/COMPONENT TESTS article, or if the test light does not blink, see IGNITION SYSTEMS in the same SYSTEM/COMPONENT TESTS article in this section.
Fig 1: Identifying TFI Ignition Module Connector Terminal
G106319Courtesy of FORD MOTOR CO.
Fig 2: TFI System Electrical Schematic
G90I09245Courtesy of FORD MOTOR CO.
Fig 3: TFI System With CCD Electrical Schematic
G90A09246Courtesy of FORD MOTOR CO.