1993 4Runner 3.0L electrical issue

Please HELP!!! I was driving my 93 4Runner the other day, when it suddenly lost all power, I mean all power. All dash lights, hazard lights, engine, everything just died. When I pulled to the side of the road and popped the hood I noticed smoke coming off of the negative battery cable / terminal. I disconnected the negative battery cable and noticed I had somewhat of a loose ground wire, and the ground wire sleeve was melted in a few spots (!and even melted itself to the plastic top of the battery. The negative cable itself looked black where it connected to the battery terminal. I cut the wire back some and reconnected it and tightened all the ground wires. I hooked everything back up and still no power at all. A friend came by and he suggested we try jumping it, which we did, however as soon as he hooked the jumper cables to his battery and as I was hooking the jumper cables to my battery, both batteries positive terminal started smoking and arcing to the point that the cables got very hot to touch and the terminal clamps were almost fusing themselves to the terminal. Obviously we immediately disconnected everything. The next day I replaced all the ground wired with new 8 Guage wired and new connectors, and new negative battery terminal clamp. Still dead, no power at all. Checked all the fuses I could easily get to and none were bad. I hooked a battery charger to the battery and nothing happened. It read 0.0 volts for an hour. Disconnected the battery from the vehicle and I am getting 13 volts, when connected to the vehicle Its 0 volts. Does anyone have any idea what might be happening or what I could check next?

 

Have your battery checked and then check your relays. Hopefully you didn't smoke the ECU. You obviously smoked more than the wire.

 

You have a major short in the system. Take the battery out and don't connect it up until you figure this out. Charge it outside the car and outside any building. Hopefully the battery is not ruined.

Use your multimeter and check continuity between the positive battery cable and ground. I'm guessing it is going to show a short to ground. From there I would pull fuses and relays and hope one is shorted. If not, you probably have a bare wire touching the engine or body and you need to find it. And you very possibly have multiple shorts.

 

The battery is out of the vehicle and measuring at 13 volts. However, when it was in the vehicle I was getting 0 volts, that is when I tried hooking a battery charger up to it and let it sit for like an hour and was still reading 0 volts after an hour. That is when I disconnected the battery and removed it from the vehicle. I'm not sure if I am correct in my understanding that the 2nd gen 4Runner does not have a "fuseable link" as they are done in newer vehicles, withe the 3 smaller guage wires near the positive battery cable, instead the 80 amp fuse in the engine compartment fuse block is what acts as the "fuseable link", do you know if that is correct? I tried taking that fuse out to measure it, but there are wires connected to the bottom of this fuse, and extremely hard to access. I'm really trying to solve this problem on my own because I have a feeling that if I take it to a shop they are going to charge me a small fortune in labor as they go through it wire by wire. I wish I understood the electrical system on vehicles in general a whole lot better than I do. I can do a lot of mechanical repairs on my own, but this is so frustrating. I will do what you recommended I do over the weekend and hopefully I will find something minor that I can handle on my own. Thank you for taking the time to answer me.

 

Yeah, if its measuring ZERO in the vehicle, with everything off, DO NOT CHARGE IT IN THE VEHICLE. You have a short to ground. All batteries have at least a little charge. They will show 9-10v even if they are bad to the point they can't be charged.

You can very easily burn the car to the ground. So you need to proceed carefully and check everything. Invest in a quick release for the battery. If you have an electrical fire, the fire can't be put out until the battery COMPLETELY discharges. And car batteries have LOTS of charge.

Luckily, the older the car, the simpler it is. Being a severe short, you also should be able to track it down easily. Check continuity from the positive battery cable to ground. All symptoms point to that being shorted. Then follow the cable to where it is connected. It should go to the starter relay. Maybe the starter relay is shorted. Disconnect it. Make sure the end doesn't touch any metal. See if the short went away. If not, keep looking.

You may need to remove nearly the entire engine harness to replace what has burnt up. Check everything. Take this time to cut your teeth on learning more about car wiring.