Glow plug controller

[Andylad13]

I burned out 6 out of 8 glow plugs and I checked the voltage going to the plug and it varies from 9.5 to 10.5 volts. If my glow plug controller is broken what would I be reading at the plug?

 

[franklin2]

Zero volts.

 

[Andylad13]

So when controllers go on the fritz and cook multiple plugs, what happens? I figured the controller may have crapped out, but I was thinking that that meant the resistor fried, and was sending full voltage. Usually when a whole bunch of plugs die all at once it's a controller problem. Not so much this time I guess.