A.This is called engine run-on and is caused by an output from the exciter circuit to the ignition system. A diode is an electrical valve only allowing current to flow in one direction.

The dash light is necessary with this type of system because without it, once the alternator starts producing current, the 14.2-volt output will follow the R wire back to the ignition switch.

We're also installing a coil over ignition system from Jacobs Electronics ,called the Jacob's Ultra Team Mileage Master Energy Pack, on our 1997 Dodge Truck. The ignition system features a CMD ...