I have 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 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.

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?

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My first thought is that there is some corrosion at the distribution bus that you circled. I'd take it apart and check each of the terminals, wires, terminal-to-wire connection, and the connectors on the bus for corrosion. If there is much corrosion in a wire or connection, then the resistance would be higher so that when the battery was attached it could overheat once the current starts flowing.

If easy enough to do, you might consider cutting off each terminal and install a new one and then either replace the distribution block or at least clean it up again. You might also add a dab of dielectric grease on it when you are done to help prevent future corrosion. I'd add at least some heat shrink to the terminal ends to protect the terminal-to-wire connection from water and also to act as a strain-relief.

This might or might not be the problem but it is easy enough to try and could be at least considered preventative maintenance.

 

In your second photo you can see the fusible link is burnt. Just tug on it and it will come apart. It did it's job and will need replaced. But something down the line shorted out to do this - that will need fixed first..