Alternator Burnout

My son has "burned" up 2 alternators on his 89 Toyota pickup within the past two weeks. It all seemed to start when the electric fan the PO installed shorted out. We've has since had to replace the starter, alternator (twice) and the battery. The alternator belts were also breaking but I think that was due to one of the mounting bolts not being securely fastened. At first I thought maybe the alt bearings were freezing up causing breakage but I don't think thats the case now. Any ideas on what else to look for?

I had a car that suffered a similar electrical fate. It started when some lady that I was giving a jump start to, in her excitement that her car started disconnected my jumper cable from her car and tossed them to the ground - of course the other ends were still attached to my car. Lots of arcing and sparking ensued. Everything seemed ok until a couple weeks later when the starter went out. Another few weeks and the alternator was bad. Electrical gremlins kept appearing - after the second alternator the shop that was doing the work noticed that a lot of the wires in the harness seemed burnt. There were lots of strange things going on and it started with a short similar to what you are talking about with the fan. Was the fan fused or did it cause sparks, smoke, lots of heat when it shorted?

I was young, bust at work, and didn't know anything about cars other than how to change the oil and replace brake pads - so that car was traded in for the first new car I ever bought - figured if I was going to spend the equivalent amount of money to keep that POS running I might as well have a car that actually worked. I am a little ashamed to say, but the messed up car was a Chevy Spectrum - it was paid for and reliable until the jumper cable lady struck then it was a living piece of dung that could not be trusted and really seemed unfixable at least for any reasonable amount of effort.

Hopefully there is a better answer for your son's truck, but this sad story is the only applicable one I have for this case. Either dig into the harness and replace any wires that are damaged, get a new wiring harness, or get a new truck - that's my guess.

Another reason not to jump start a strangers car. After frying an ignition module in a Dodge van 20+ years ago, I have never volunteered to do this. Yeah, I'm a bastard.

I'll use my jumper pack to jumpstart from here on in...

Had an alternator voltage regulator go out that caused a high voltage condition.........It fused/burned a relay for my fan...that melted a wire to the starter solenoid (the little one)......that jacked with my front turn indicators and my temp sending unit somehow.

Pushbutton starter I installed had me understand that the solenoid wire also acted as a ground for several relays and somehow if I disable the door chime, my wipers won't work.

Modern wiring diagrams should have parts labeled "Here There Be Dragones"

Bruce

Sounds to me, like previously mentioned, the harness melted together for sure. I had a MG with similar issues after the main going to the starter hit a ground. If nothing else, go through as much of the harness as you can and just make sure the individual wire insulations are not fused together. I had multiple problems fixed (short term of course) but just getting fused insulation for the wires apart, then later replacing what ever was melted through.