Ignition Coil Primary Circuit Switching Check

Insert a small straight pin in wire to ignition coil negative terminal about 1" from ignition module connector. Attach test light between straight pin and engine ground. Crank engine. Remove test light and remove straight pin from wire. See Fig 1.
NOTE: After test is completed, apply a small amount of silicone sealer to pin holes in wire.

Fig 1: Testing Ignition Coil Primary Circuit Switching
Courtesy of FORD MOTOR CO.
If test light flashes, proceed to "IGNITION COIL PRIMARY RESISTANCE CHECK ". If test light comes on but does not flash or if test light does not come on at all, proceed to "WIRING HARNESS CHECK ".