ENGINE RUN-ON
If your engine continues to run even when the ignition is turned Off you are experiencing
engine Run-On. This usually only occurs on older vehicles with an external voltage regulator.
Because the MSD receives power directly from the battery, it does not require much current
to keep the unit energized. If you are experiencing run-on, it is due to a small amount of
voltage going through the charging lamp indicator and feeding the small Red wire even if
the key is turned off.
Early Ford and GM: To solve the Run-On problem, a Diode is supplied with the MSD in the
parts bag. By installing this Diode in-line of the wire that goes to the Charging indicator, the
voltage is kept from entering the MSD. Figure 6 shows the proper installation for early Ford
and GM vehicles.
Note: Diodes are used to allow voltage to flow only one way. Make sure the Diode is installed
facing the proper direction. (Cathode toward regulator).
Ford: Install the Diode inline to the wire going to the #1 terminalGM: Install the Diode in-line to the wire going to terminal #4.
