I drove it to check on a job, had no problems, shut her down, and when I was ready to leave it fired right up and then died before I could even get it in gear.
One very possible explanation for that is that the alternator started putting out way too much current and the link fried to save the wires.
In this pic is the fusible link the fat black piece right at the relay terminal (disconnected). It's melted some but both the black/red stripe and yellow wire connected to it still Ohm out when I check it about 6" from the terminal.
Yes, that's it. And yes, it's fried.
A failed link might still ohm out because the current required to get a resistance reading is minuscule by any standard. As soon as something really tries to work offf that current (such as a lamp or motor or relay) there just isn't enough to work the load.
So yours doesn't have that rubber tag on it huh?
Maybe mine is one of those aftermarket wires Paul mentioned.
Pretty sure that at least most Fords did not use a tag in the early years. And while I've seen them on Broncos and later trucks, there was really no way for me to know if they were original or replacements. But up to at least the early to mid seventies they were tagless in my experience.
I can't find anything on that fat black connector either, but obviously part of it is melted. Could those wire still Ohm out, but not be able to carry any draw?
Exactly right. And melted it melted no matter what. It takes quite a bit of heat to melt this type of rubber/plastic material, so that was created basically by a melting wire.
Very hot stuff...
Enlighten me those in the know... did ALL Bronco's come with fusible links or what year did Ford start using a "fusible link" in a Bronco wiring harness?
Yes to at least after '66. Supposedly they were even on '66's and as far as I know were in use before that. But I have seen '66's without the links too, but with no way to tell if they were unmolested or not.
A member here (gddyap) has a '66 that, while the harness looked factory fresh, didn't even have a fuse panel!
He re-wired it thankfully, so now it has full protection. But at the time he bought it there were only some old inline fuses and no fuse panel on the firewall where it would have been expected.
Either it was very professionally re-done without it, or it was a Ford experiment! Even cars and trucks from 50 years before had fuses after all. No reason for Ford to try to work without. But it was really strange to see and made for some interesting conversations.
Looks like I may need to change the title! If I do have a fusible link it is not burnt. I have confirmed full voltage at the big connector on the firewall side plug. See image. Now what???? Maybe disconnect that male/female connector near the ammeter and see if I have power there?
Yes, but not really needed yet. Fix the melted end at the starter relay and then check for power at the connector. As you've already found out you can measure voltage after the failed point (because there's no heavy current draw from a volt-meter.
It is strange of course, and will mess with your mind. And it may very well turn out that there is plenty of capacity available and the break is somewhere else. But like I said, melted is melted so you need to fix it just in case. Even if it's not the main problem, it's a problem nonetheless.
Thinking about it though, you might as well pull that connector apart anyway to check it's condition. It would not do to fix the main break only to find out this connector is rusty and ready to fall apart. I've seen that happen and it's not a good idea to let that much resistance midway up the wire build up to the point it could cause more trouble still.
Such as another blown fusible link!
Just so you know what you're dealing with, that Black w/yellow wire that comes off the back of the alternator, and the Black w/red wire that comes off the starter relay, and the large Black wire next to the ammeter with the connector, ARE ALL THE SAME WIRE in a Bronco. It's one big long loop.
That's how the alternator charges the battery, and how the battery powers everything when the engine is off.
Hopefully that helps make more sense out of this stuff.
Oh, and the Yellow wire there is likely for the voltage regulator's "A" terminal where it measures battery voltage so the regulator knows how much current to tell the alternator to produce.
There would be another Yellow wire directly to the starter relay on '74 and later EB's, but that one is for the horn relay and is a little larger gauge I think. But they're both Yellow and can confuse things a bit when looking at a diagram.
Good luck.
Paul
