Electronic Ignition: Description
System is comprised of a magnetic distributor, an electronic control unit, wire harness, coil, and a special dual ballast resistor.
The primary circuit consists of battery, ignition switch, compensating side of ballast resistor, primary winding of ignition coil, power switching transistor of control unit, and vehicle frame.
The secondary circuit consists of the coil secondary winding, distributor cap and rotor, spark plugs, and vehicle frame.
The compensating resistance serves the same purpose as in the contact type ignition, that is to maintain constant primary current with various engine speeds. During starting this resistance is by-passed applying full battery voltage to ignition coil. In addition to the two basic circuits there have been three other circuits added, they are the pickup circuit, control unit feed circuit, and auxiliary ballast circuit.
On some engine models a solenoid has been added to aid in starting. It receives power from the starter relay at the connector that sends power to the starter solenoid. When actuated it advances the spark 7.5" (engine).