Ignition System - MOTORCRAFT Electronic: Operation

The electronic control unit and ignition coil are turned on whenever the ignition switch is in the "START" or "ON" position. As each tooth of the trigger wheel passes the pick-up coil, it interrupts the magnetic field around the pick-up coil. This continual build-up and collapse of the magnetic field provides a signal to the MCU.

The MCU receives the pick-up coil signals, along with other engine sensor signals, and sends a spark timing signal to the electronic control unit. The electronic control unit then turns off current flow to the ignition coil primary circuit.

The collapse of the magnetic field in the ignition coil primary circuit induces a high voltage surge in the secondary circuit. This causes current to flow from the coil to the distributor, rotor, cap and spark plug wires.

Ignition timing is constantly changed by the control unit, the MCU, and vacuum and centrifugal advance mechanisms according to engine operation.

NOTE: When disconnecting wire from spark plug or distributor cap, twist rubber boot slightly to loosen. Grasp boot (not wire) and pull off with steady, even force.

NOTE: When disconnecting control unit connectors, pull apart with firm, straight pull. DO NOT attempt to pry apart with screwdriver. When connecting, press together firmly to overcome hydraulic pressure caused by the silicone dielectric compound. If connector locking tabs weaken or break off, it is unnecessary to replace connector. Just press firmly together and bind with electrical tape or a harness tie strap.