Fuse 16 / electrical help

[Pinkston]

My Comanche started life as a 89 2wd 4 cylinder. The PO put in a 4.7 stroker.  I've owned it for probably 10 years. Last year I converted it to 4wd. 

The wiring has been trouble free but looks a little sketchy. Yesterday while driving the 30 Amp engine control fuse blew and I costed to a stop. While figuring out what caused it to blow I traced a wire the PO  had run to the engine bay fuse block to the under dash fuse block. The wire is circled in my picture. It had a 30 Amp circuit breaker in it. Removing that circuit breaker seems to have fixed my engine control fuse problem. 

What I'm trying to find is what that circuit breaker does and hopefully a wiring diagram. I think its for the power windows which were added by the PO.