Originally Posted by psgugrad
Ok but how do you get the voltage down?
Well the onboard glow ignitor has its own electronics built in that reduces the voltage down to a safe level for the glow plug. They usually include a circuit for measuring the current flow and adjust it as well, plus they include a circuit that allows you to set the turn on based on the throttle position too.
You can also perform a GOOGLE search for "glow plug igniter schematic" and see if any of those methods that show up will work for you too. Unfortunately some are from another forum though.