Electronic Control Unit

The electronic control unit is located in a metal housing on the firewall. A switching transistor is exposed on top for more efficient cooling. The control unit is connected to the rest of the system by a wiring harness and a 4-wire connector. The control unit functions whenever the ignition switch is turned to the "START" or "RUN" positions.

The control unit furnishes current to the distributor pick-up coil directly on single pick-up models. On dual pick-up models, current flows through the dual pick-up start-run relay to either the start or run pick-up assembly, depending on whether ignition switch is in the "START" or "RUN" position.

The signal created, as the reluctor teeth pass the "live" pick-up coil, is transmitted by the control unit to the primary circuit of the ignition coil. As current to the primary is cut off, the magnetic field there collapses, causing a voltage surge in the secondary windings. This fires the spark plugs.

The length of time current is permitted to flow through the coil's primary circuit (dwell time) is determined by the control unit and is not adjustable.