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 on and 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?

1 Posts gets 12V and the other gets nothing with the key on.

Any help, thanks guys.

[Zander's 5.8]

The PCM grounds one of the small posts when the GP's are commanded on, the other small post is battery voltage. If it's not grounding one of the small posts trace the wiring back to the computer to make sure it's ok. Or find out what pin it is on the computer and test for continuity on that wire. If there is no ground signal from the PCM it's bad. One of the large posts should have constant battery voltage and obviously the other post gets battery voltage when the GP's are commanded on.