Glow plug/relay prob :(

[slammed83mazda]

My glow plug relay has always worked and would start on the coldest days, before you could hear the relay click ona nd hummm. Well about 3 days ago I decided to play in the mud and I'm guessing I shorted something. Now the truck won't start unless its plugged in at night. Replaced the relay and still same problem.

Can someone run this down for me real quick on what to check? Maybe I missed a fuse or a relay in the box?