hi , this is commonly a bad controller or bad glow plugs here are a few tests to do and let me know what you find,
Where is the glow plug controller located at? The relay for the glow plugs on top of the engine only has power to it where the main cable connects. Should I have power to any of the terminals when I turn the key on?
the controller is actually what looks like a relay on top
yes there should be power on the big wire feeding the relay