Did something stupid today

[gmcnoob]

Long story short is I had the battery and the alternator both disconnected for some electrical work and I reconnected the battery before the alternator. The wire for the alternator was touching the valve cover and there was lots of sparking there and also at the junction box on the firewall. Now I just have exterior lights and the courtesy/dome light, nothing else. Did I fry the fusible link at the junction box? Did I damage anything important? How do I fix this?

[Liberty]

Well atleast most of these trucks are not computer controlled, if your truck is there is a huge chance you killed that computer.

If you are lucky you only killed all the fuses. So I'd disconnect the battery, leave the alternator plugged in, and check all the fuses. Lucky for us, the fuses are all transparant and are pretty obvious which ones blew.

Check all of your wiring, make sure nothing melted. It would be a big problem if a hot wire melted and is now causing a short somewhere.

Based on my experience when my starter system shorted out, your neutral safety switch might be dead now, which may not allow your truck to crank.

I'm going to assume your fusible link is fine since your lights work.

So really all you can do is check the wires, try new fuses and see if it starts.

[buddy_1]

Year model?

[buddy_1]

I looked at your profile and on your 86 you should have 3 fusible links. 2 at the starter and 1 at the junction block. Easy way to check them is to pull on the wire. If it stretches or breaks it is bad. If you have a multi-meter you can ohm them out end to end. See attached diagram. Buddy

[gmcnoob]

Thank you!

[gmcnoob]

Originally Posted by buddy_1

I looked at your profile and on your 86 you should have 3 fusible links 2 at the starter and 1 at the junction block. Easy way to check them is to pull on the wire. If it stretches or breaks it is bad. If you have a multi-meter you can ohm them out end to end. See attached diagram. Buddy

Is this one of the fusible links on one of the red wires? This junction is where sparking occurred. Why would that happen there? I can't seem to find any wire online with these fusible links built into them. Not sure exactly what to do to fix this.

[buddy_1]

The wire with the pellet in it. Pull on the pellet away from the junction. If it breaks it is burnt. The fusible links are designed to melt inside the insulation. The pellet is the splice between the regular wiring and the power source. You also need to look at the starter solenoid for two more wires with pellets connected to the large post. See diagram above. The section of wire between the pellet and the eyelet at the end is the link. Buddy

[Titomars]

Head lights are not fused, a Federal safety measure. that's why they still work.
Yes that is a fusible link at your junction block. The one with the fat black band around it. A fusible link is nothing more than a wire 2 gauges smaller than the wire it feeds to. fusible link wire is only different from regular wire by its insulation. It is a hypalon insulation so it does not burn and melt like the standard plastic covered wire. parts stores like Napa sells hypalon wire in various gauges.