I have a 1992 f 350 7.3 idi. Got the truck with problems with glow plugs. I have no wait to start light. Glow plug relay just clicks when you turn on the key. New glow plugs, new controler, and a new glow plug harness. All fuses look good. I'm pretty much lost right now. Tested the gp relay and getting power to the constant and ignition side. Just have no power to the glow plugs at all. If someone can help and maybe post a few pics of what I'm supposed to be looking for that would help

 

I have a 1987 F-350 7.3 with much the same problem. GP relay just clicks on-off, on-off , on-off and cranks good but won't start. Belongs to a friend and just got into checking it out. Could use help also.