My fusible link blew out today. The nylon connector started to melt, but the link went out, as designed. Before I found that, I discovered that the negative terminal on the battery was loose. I tightened that, is that a possible cause of the problem, or should I look for another root cause? Practically everything underhood is new on the car. I will replace the link, but I'd like to figure out what the problem is rather than just treating the symptom. Any suggestions would be appreciated. Thanks!

I don't think that the neg cable being loose caused it. Here's a dumb question , what is the amp output of your alternator ?

I don't know what the output is, I don't know how to tell the difference. It's the same alternator that's been on the car for 20 years, just an original factory rebuild.

The link would only "blow" (it actually melted, arced and opened) . . . if there was a short circuit somewhere.

Did you do any electrical work recently ? Is all your wiring ok ? Maybe there is a pinched or chaffed wire somewhere that finally is touching ground ?

I had a rebuilt alternator, where the insulator for the battery post, was broken and intermittently touching the case (ground), until it finally broke thru totally and short out the battery - thus taking out the fusible link . . . just a thought . . .

Mark

Hmm...I for some reason was thinking that high resistance would cause it to blow, but I think you're right with a short... I just rebuilt the car, so EVERYTHING has been done recently. All new underhood, reconditioned underdash. I can't imagine what would be shorting out, everything is working fine. And isn't mostly everything protected by fuses? Wouldn't fuses blow before the fusible link?

Edit: How about the voltage regulator? If that was malfunctioning could that cause this problem? Alternator is newly rebuilt, the voltage regulator is 20 years old.

Definitely too much (amperage) flow as said. I suspect the loose batt connection is the culprit though I'm not sure how this let the batt get undercharged then the connection touched and it then charged too high to catch up & overloaded the FL.

I recently replaced mine due to a short. (power wire to the stereo abraded by the motion of my hydraulic clutch cylinder) Napa carries replacements, you just have to add your own ends.

The negative battery terminal being loose doesn't seem to me to be a likely cause as its only effecting grounds.

I'd get up under the dash and start looking around for any obviously damaged or frayed wiring to start.

-Jon

(my valiants mess)

It's right: If there is a short under the dash or so, any fuse should melt first.

Check the bulkhead connector (if you still have one) if there are melted sections - if not, the problem is probably in the engine compartment.

There are a number of wires that are not protected by fuses - connecting alternator and starter. Usualy the fat ones... check them for melted isolation.

If "everything is new" than may be any wire was fixed to something sharp so that after a short period the isolation was rubbed off (or to close to exhaust??).

If you don't find anything, replace the link and try again. If it melts again, you should really insist finding it...

I would replace the fusabel link

Your pictures are way too big, pls repost them smaller!!

Before you replace the link, Put a large 12v bulb across the terminals, such as a tailight bulb. If you have a a dead short, just replacing the fusible link can cook off more insulation off of the shorted wire before the link melts. That wire is probably the red wire bundled tightly with all of the other wires under the dash.

If you have a short, the bulb will light up. The bigger the short (or current draw) the brighter the light will light. Then start unplugging connectors till the light goes off. It will help you narrow down which circuit or harness to concentrate on. Use a smaller bulb to find small current drains between the battery post and the batrery clamp.

BTW, A common problem in an e-body shorting fusible links or melting the harness is the one of the ammeter terminals shorting to the cluster housing because the mounting studs were loose or not centered. Check that first. No fuses in the box protect this circuit. Only the fusible link.

It looks like it's possibly the alternator. The melted connector on the fusible link was discovered because it coincided with the car not charging, but the link is still functional. There are no other melted wires, blown fuses or shorts that I can find anywhere, including under the dash. Ammeter wires look fine, ammeter functions and bulkhead connectors and wires are all clean and nice.

I had discovered the negative terminal on the battery as well as the terminals on the alternator were slightly loose, tightened all of those right away. Still didn't charge, so I checked the following:

-belt tight
-good battery to body ground
-regulator grounded
-tried additional new regulator
-alt is grounded
-12V at alt field with ignition on
-no voltage change at battery, running or off

Still no charge. This lead me to believe that maybe the alternator was overcharging due to additional resistance from the loose connectors, melting the connector on the fusible link (without breaking the link, because there was no extra draw, i.e. short) and ultimately frying the alternator. Still need to go get the alternator tested. Does this sound logical?