I have a 99 SR5 4cyl that started sounding a bit funny, and running a little bit rough. When I tried to turn off the engine the motor it kept on running. It sounded different but I think that was just because much of the electrical system had stopped when I turned the key. Since it was still running I turned the key again. Now it sounded fully engaged. I tried to turn it off again and the same thing happened, it would not shut down. Then it started smoking. Now I've got the key in my hand, the engine is running but weakly and the smoke is getting thicker. It took a few minutes (felt like a lifetime) to get the battery disconnected but the engine actually quit running before I was able to get the battery disconnected.
The rubber coating on the negative battery cable is melted. The smoke was coming from down low on the battery side (drivers side) of the engine. I'm very sure I've burned up a harness that was there.
I'm not sure if the engine seized or if the short finally caused it to quit. I'd appreciate any ideas of how to figure out if it's worth fixing. I love this truck and would love to fix her but I need to think of best and worst case senarios.

 

I'd would start by removing the battery and the heavy duty fuse box beside the battery and take a look at the main power connections underneath the fuse box, its a bit tricky to get the fuse box apart at first, main fuses and connections are bolted in place and do not just pull out, but it sounds like a main power supply from alternator or battery has crossed to ignition power supply making the key inoperable, perhaps chafed wire coating failure or connection failure/cross over, and it finally shutting down was a either a fuse that finally burnt up or the offending power supply broke/burnt up its contact, unfortunately beyond that I would be difficult to sort out the damages without chasing the wires and associated components where the smoke emitted to isolate the other damages that occurred. Everything is very well protected usually so if you can sort out the power supply failure/crossover you might be able to get everything working again.

 

Thank you, this gives me some hope and somewhere to start. I appreciate you.