Went out to start the truck the other day and nothing. No lights, power ect. Found this broken wire (next to red wire) and that's the issue. Is that black rubber piece a fusible link? If so, i'm not sure how to fix this since it broke off right above that fuse. Since there is another wire going in there, the only fusible link wire I can find are the ones that have a regular fuse in it. Do I just splice this in with this fuse wire and bypass the black original one?

 

I could be wrong but I think that’s just a junction where all the wires meet. You check a wiring diagram to confirm.

if so just cut it out and replace.

i had wiring like that and it was basically falling apart everywhere, which prompted me to re-wire the entire thing.

 

Thanks. I'll do that. Yes I can see how a new wiring job would be desired. These wiring casings just feel so brittle

 

Yes, that's a simple (but normally very robust!) splice that Ford uses. However, it is in fact in the fusible link wire.
You can see that it's a fusible link further up the line where the "flag" is just before the ring terminal at the starter relay/solenoid post.

Best to find out why it failed there though. Did it just simply deteriorate over the last 50 years or so? Or did it get overloaded, and rather than melt up by the relay like I see most often, by something else amiss?
Is that the end that goes to the alternator? It looks like it, but for it to cut power off to the whole truck, it should be the branch that goes up to the firewall and feeds everything power.
If it's the cabin power, then it might have a short in it somewhere.
If it's the alternator side, then maybe the alternator or regulator failed and overcharged it.

Did the truck run well before this? Looks like a project in progress, unless you simply have the sheet metal off of an otherwise running truck at the moment?
If you get it started again, be sure to check battery voltage as soon as you can. If it's between 13.5 and 14.5 volts, your charging system is doing it's thing. Usually 14 to 14.5 is what they tend to work at.
But if it's over 15v then it's overcharging and you need to find out why.

If it's under 13 then it's not charging much at all, so is not necessarily what caused the problem. But it's still worth finding out why so you can get things working again.
Of course, it could just be that the wire got old and tired. Or had been overheated to near failing in the past, and just finally gave up the ghost.

Good luck.

Paul

 

By the way, does your truck have an ammeter in the dash? Or just a battery light?
Was wondering about the Red wire there in the splice, and thinking it might be one part of the ammeter shunt. But I don't have the diagrams in front of me, so not sure.
What year is your truck by the way?

Paul

 

Paul,
thanks for chiming in. it definitely deteriorated. the fusible link is fine. and its definitely a wire that controls a lot of stuff. When i 'stuffed' it back in that black junction, the lights came on and the ignition worked. the truck ran just fine until this wire broke.

i just picked this truck up a month or so ago. Its a 72 F250 camper special automatic. The vin says it has a 360 but the motor has a tag on it that says 1972 390 so someone must have changed it but thats fine with me cause I bought it to pull my camper. It has a dana 60 rear end with 373 gears. Overall the truck is in good condition. It needs some work on the floor pans and a bed floor but other than that not too much has been eaten up. It doesn't have many options...it has all power drum brakes and manual steering. As luck would have it, i found a late 60s F250 2wd in a junk yard that had power disc brakes and power steering...so for a few hundred bucks, i was able to pull all that stuff so thats on the agenda to get this all installed by memorial day weekend.

 

It’s not surprising to have things like that deteriorate over this amount of time. Some seem to last forever, while some might’ve had some slight defect or compromise a long time ago, and it finally just let go.
It’s also something that may very well have caused the previous owner to sell. The truck could’ve had intermittent electrical issues that they couldn’t find.
Glad you found it quickly!

As suggested earlier, you may just end up cutting that all apart and splicing it all together yourself.
Since the fusible link is still intact, you don’t necessarily need to add a fuse to protect things.
But, sometimes a fuse holder acts as a nice splice point.
So you do have options and choices.

 

due to weather, haven't been able to do much but i was able to look at this today. I cut the wire on the other end of the junction and saw that it was a good bit larger than the other black wire. So, am I correct that the red, yellow, and both black wires are all tied together inside that black piece? i tried cutting that thing in half to see what I could see and managed to slice my finger open so I cancelled that idea. I included a pic of the wiring diagram and do you agree that I think the circled junction is where I'm at? I was confused because the 10 gauge wire looks like its coming from the alternator but the wiring diagram doesn't show that. The diagram only shows 3 wires joining from the alternator and not 4. I need a red, yellow, black fusible link and the 16g black.....this config is only shown where I circled. So, do i need to completely cut that junction out and re-splice all 4 wires together?

 

Yes, that is a factory splice.
The larger black wire is the battery charge wire from the alternator. In essence, it is connected directly to the battery and should have battery power at all times.
Any wires connected to that splice get power from the black wire and send it to their various functions.
Yellow and/or Red are often for the ammeter shunt. but I can’t see all of the diagram.
Yellow wires power up things like the horn relay, the external voltage regulator, and other things.

 

Oh, and the 16 gauge black with red wire is simply the ground wire, connecting the case of the alternator to the case of the voltage regulator on the fender.
It’s a reference ground, if you will, to give both the regulator the same ground value as the alternator itself.

 

There is information the the service manual ; electrical maybe , that shows how to repair fuseable link .
Not 100% on this but I believe there should b a pink wire or two in there that melts if something overloads
I would wash all the wires and see if there is a splice under the tape that PO may have made . He may have used the WRONG wires
I would see just what is there , & what should b
I read many moons ago fuseable links were not used until 1972 or maybe 1973 . Which does not make sense since it is in the 1971 service manual
The tag kolur' tells what amp rating it is

 

Can’t say about all vehicles, or even all Fords, but we know that, at least back as far as 66, Ford was using fusible links to protect the main power wires.
At least on some vehicles, if not all.

Easy enough to replace a burned out one with something easier to maintain, such as a 40, 50, or even 60 amp MIDI, or Maxi-Fuse.

 

You NEED 2 know which one !
Wouldn't you have to install a fuse holder the way described ?
Manual says reinstall wires.............I think..............

 

The fuse is fine. The wire 'corroded' off right at the junction where 4 wires are joined. I cut the main wire where it went into the junction and spliced it in with the other wire that had broke. Then tied the red and yellow wire in with them. Definitely not what I want long term fix but until I want to tackle a new wire install it will do.

 

No, you need to determine which one to use in any particular installation.

[QUOTE=RTT;21120911]Wouldn't you have to install a fuse holder the way described ?
Naturally. I almost typed that in my message, but it should be obvious to anyone that can do wiring, that to install a fuse correctly, you need the correct fuse hardware.
Now, that said, I've certainly seen where people installed a bladed fuse using just two push-on blade connectors at the end of wires. But that has, thankfully, been the exception rather than the rule.

Probably. And probably because if that's how the factory does it, then that's how the factory manual says to repair or replace it. Like with like.
But some factories don't use fusible links. They use fuses instead. I've even found Mega-Fuses (and their holders of course) on Mercury Mountaineers.
Never saw one on a matching Explorer (same vehicle as the Mountaineer) where I've only seen a double fusible link array at the end of the main 6ga battery charge wire from the alternator. Maybe they use links elsewhere as well, but I've only seen fuses and circuit breakers in the rest of the circuits of a more modern vehicle. Might use fusible links and I have just not run across them, but I've seen them only in the charge wires.
We often have two, or even three of them on our older trucks.

While the use of fusible links is obviously practiced for a reason, I am not fully aware of what that might be. I've seen the videos and descriptions and explanations, and still feel that there is nothing inherently wrong with replacing an old burned out fusible link with either a circuit-breaker, or a properly sized fuse. I feel that in a pinch, fixing one of those is as quick as replacing a fuse, where replacing a fusible link wire is a whole lot more involved. Not fun on the side of the road or trail.
Perhaps that's why they do it? Getting you to take more time to diagnose what blew the link in the first place, rather than being tempted to just throw another fuse at it?
Centech Wire includes fusible links with some of their aftermarket wiring harnesses. Most others include either a Maxi-Fuse (and it's holder) or a Midi-Fuse (and it's appropriate holder).
For now, even though I keep a few fusible link wire sections of different values in my wiring tool box, I would probably still replace them with a fuse if I had the chance.

Paul