I've replaced the glow plug relay (comptroller) with a ford starter relay on my 6.5 TD with a push button in the cab. I can hold the glow plugs on as long as I need to. I have Bosch self regulating glowplugs so if you leave it on a little longer than the comptroller would, they don't burn out. Starter relay is a lot cheaper than new comptrollers are and the contacts are much larger so they don't burn up quickly and have less resistance. The relay will probably outlast the truck..........
