(EDIT: Reposted in electrical)

I have had an 83 K5 for the last 9 years. I don’t use it often and it is parked in the driveway. To keep the battery from discharging, I disconnect both cables from the terminals and reconnect them every few months to start her up.

The last time I began this procedure, as soon as I connected the last battery cable, smoke started appearing from something on the firewall. I immediately disconnected the battery cables to prevent a fire. The keys were not in the ignition at any time and the headlights were not on.

After getting a fire extinguisher out of the house, I repeated the procedure and this time there was no fire/smoke. But the engine would not crank at all once the key was turned. No clicks. It was as if the cables were not corrected to the battery.

I want to figure out what the problem may be. Or maybe I should say my teenage boys are also keenly wanting to figure out what the problem is.

pictures attached. Any thoughts?

 

That block connector on the firewall, is that battery voltage or ground, there are both black and red wires? I assume that’s where the smoke was coming from? Do you still have 12v at the big power cable connection on the starter?


George

 

Tom

I don’t have any K5 schematics, do you have the hook up on the starter circuit?

Thanks,

George

 

The diagrams for stuff that old are pretty bad. IIRC, though, that's a fusible link that I thought fed the HVAC circuit, but I don't have my K5 here to look at. The starter circuit is almost all purple wires, so it's pretty easy to trace. What's the owner-added black wire on that junction block? It doesn't look new, but it could be the source of the short.

 

That was my first reaction that a fusible link smoked since it stopped. The question is why? Rats, rain, loose connection moving and shorting like at that block.


George

 

The truck has never had any problem with starting before in 9 years, except when I left the battery connected, there was a draw somewhere since the battery would not last more than a month between starts.

 

what do you think about that exposed wiring on the drivers side of the junction block. Is that exposed wiring indicative of burning off or a rodent chewing?

 

OK, I think I found a wiring diagram for your engine compartment, I think. That block on your firewall is a simple junction block. The left red wire should be battery voltage and the two right red wires are that battery voltage being distributed to the alternator etc. That black wire is a hack and does not belong there. Its also the wrong color so where ever it ends up has 12v on it with the color of a ground wire so be careful. If you want to get to the bottom of your parasitic draw problem after we get you started I would start with that "add on". Also that ring connector is too big so that connection could get wonky. There are fusible links everywhere in this power distribution scheme which are sections of wire intended to burn open with a high current short circuit. That may be where your smoke came from. They can be a PITA because unlike a simple fuse replacement you have to do a wire harness repair job.

First make sure that none of the connections on that block are loose and that non of the terminals or exposed wires are touching any of the metal except the threaded posts and nuts. Second, measure the voltage on that left post and on the big black post under the truck on the starter solenoid. Assuming that your battery is at full charge and reads 12.6V at the battery posts.


George

 

thanks so much for the help. I am out now, but earlier, I did the following.

With no key in/lights on, I connected positive cable to battery. Put voltmeter between negative battery post and negative battery cable (kinda in-line). It reads 12.5V. So to me that means a short.

Next, I connected the voltmeter from negative battery post to the red wire of the two pin connector on the side of the alternator (other wire is either black or dark brown) and got 12.5V.

When I follow the wire that is black at the junction block, it becomes green within 6 inches and later disappears through the firewall near the brake booster.

 

Get under that truck and see if you have 12von the big black cable on the starter and then see if you have 12v on the purple wire at the starter solenoid when the ignition switch is in the start position.


George