Let me begin by saying i am a very novice mechanic. Mostly self taught through internet tutorials and mostly learned due to financial necessity.

Now for the problems. My 98 Durango was having an electrical problem that was showing all the symptoms of a bad alternator. Symptoms being: the battery (brand new) was not charging as I was driving. The accessories would lose power first as I saw the battery power draining, then the entire dash and eventually the engine would lose all power. I limped down to the auto parts store to have them test the alternator. They tested it in the truck and it was only producing 11v at the battery. Awesome, problem solved.... NO! I removed the alternator on the spot. I brought it in to be bench tested. The thing passes the bench test with flying colors. Ok so maybe a short in the cables. Here's where it gets worse for me. I reinstalled the alternator and was planning on limping it home. But it it seems i have exacerbated my problems. After reattaching the alternator and going to reconnect the neg lead on the battery i notice a little arcing between lead and terminal.. Odd... Try to start it back up, things aren't working too well, maybe worse than before. I examine things and notice the 140a fusible link is blown. Ok im thinking. Maybe this was the problem to start with. So I get a new fusible link, blows out immediately upon reconnecting the neg lead to the battery. Checked all connections, cleaned and re-connected. New fusible link. Same problem.
Now im stuck, tons of research, no answers, my heads spinning. Did i reconnect the alternator wrong? (I REALLY dont think i did) Does the Neg lead off of the PDC connect to the upper stud on the alternator? I couldn't find any good pics or diagrams online. I plan to replace the neg lead from the PDC to the alternator. But before i do and blow more fuses i want to ensure i am connecting to the correct spots. ANY help and/or pics of the back of the alt when connected would be greatness greatly appreciated. Thank you in advance!

 

Sounds like you've got yourself a gremlin there. The stud on the alternator is the positive output to the PDC and the small connector is a signal to/from the computer. The alternator grounds through the bolts to the accessory bracket. Here's a link to PDFs of the service manuals which have all the wiring diagrams in them: https://www.mediafire.com/?xu9h0gt9bdcn6

 

So figured out the problem with the fusible link blowing out. Had it wired wrong. I know, what a dumba**! But you live and you learn i suppose. Still chasing down whats causing the actual problems. Possibly a short in the switch for the headlights, the switch has been giving me problem starting shortly before all these other issues. Is it possible that a short within the headlight switch could cause all these problems?

 

Your issue could be anything from a short somewhere to a loose or dirty connection(s)..

 

Its definitely a whole new ball game for me getting into the electrical side of things. My other ventures such as changing drive shaft and steering spindles and other whatnot (all purely mechanical) have all went very smoothly. I will post an update once i locate the problem and hopefully some pictures to go along, just in case some other dumby like me is reading this down the line and has similar problems.

 

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I've experienced the samething after and engine change, reinstalled the engine now it pops the fuse link (140A) which is labelled for the alternator. After looking everything over one of the positive leads going into the PDC was sent to a ground and not to the Alternator like it should have been this popped the fuse and took out the compressor clutch and the horns... not fun hunting this down. The horn and A/C compressor share circuits and its important to realize that when trouble shooting your system.