I have an '84 Chevy C10 6.2L diesel and it will not start. The only way we can get it to start is by replacing a fuse located under the hood near the back by the starter. A while back the alternator belt flew off while I was driving it and we think it may have hit something. We've replaced the alternator and that's not the problem.
I am taking a guess here but am also sending the harness diagram along. On the glow plug relay there are two fusible inks that lead to fue #1. Those may be burnt up or the diode may be bad causing the fuse to blow.