My friend had a no-start (low battery) on his 86 F150 4x4 4.9 so he hooked jumper cables from his Crown Victoria and went inside the house for 30 min.
When he came back to the truck he realized he had hooked up the cables wrong. The Crown Vic battery and truck battery were both dead. And several wires were burned up on the truck. I was able to get his Crown Vic repaired by replacing a fuse and charging the battery.
I didn't have time to try diagnosing the truck that day. Since then, he taped up all the burnt wires and replace the alternator with a reman unit. But it still has a short to ground somewhere when he hooks up the battery cables.

I guess one thing I need is a wiring diagram for this circuit and of course any ideas on what circuit is likely to have a short to ground after having the jumper cables connected in reverse polarity.
I have not started trying to diagnose this yet but I'm about to get started now. I'll post any details I find.
Thanks for any help!
Mike