main fuse

Sorry I'm headed out soon. Although ironicly my FABO doesn't crash my laptop so when I have internet service I can check in after work sometimes.

If its a 12 gage fusible link originally then its an optional heavy duty wiring. This was most common on a-bodies with rear window defrost grids. Do a search for rear window defrost wiring.

Normally its a 16 gage link to protect the 12 gage wires. The advantage of the link was it doesn't melt with a spike or even a few seconds of high current.

They can also fail when 'abused'. In quotes because its not intentional. It can be as innocent as recharging a severely discharged battery by driving on the highway. If the ammeter is showing over 20-25 amps in or our of the battery - that's going to heat connections and wires up. Which ones fail (melt first) under those situations will vary.

But if the link melted quick, then its probably a dead short. If its after the ammeter, you may have had a chance to see the needle go full discharge (40 amps+) before the link melted.
At a minimum use an ohmmeter to check for dead shorts before reconnecting the link.
The '73 wiring diagrams are a little complicated. I've posted simplified versions just showing the main circuits for both the standard and the heavy duty wiring. Those should help you.


If you think the problem is still there, rig a test lamp in-line. Don't try to start the car or anything. Just use that to show if there is a ground so you don't go through a bunch of links while hunting the short.