Click... click.

[davepl]

Moral of the story: always disconnect the negative cable when working on electrical.

Short version: I had the truck up overhead on a lift and decided to tighten a cable clamp that holds my run of heavy-gage wire to the 7-pin trailer connector. As I did I could hear "click... click..." coming from the engine.

Turns out the clamp had bitten into and was shorting out the big 8-gauge run from the AUX battery. Fortunately I had added a 50A auto-reset breaker on there or I would have had a very nice fire up in an area where I couldn't easily get to things (because it was up on the lift). Ideally I would have had the peace of mind to run and get a cable cutter but who knows.

What would the factory run in this case, a fusible link? I have some parts-store fusible link sections but nothing that looks like it would carry 50A.