Ignition Coil Primary Circuit Switching
- Place ignition switch in "OFF" position. Disconnect wiring harness connector from ignition module. Inspect connector for dirt, corrosion and damage. Repair if necessary. If okay, reconnect harness. Connect a non-powered 12-volt test light between coil "TACH" terminal and engine ground. See Fig 1.
- Crank engine and observe test light. If test light comes on or flashes, remove test light. Proceed to IGNITION COIL PRIMARY RESISTANCE test.
- If test light does not light or if it is very dim, remove test light. Proceed to PRIMARY CIRCUIT CONTINUITY test.
Courtesy of FORD MOTOR CO.