I have a couple questions regarding fusible links. Forum members have answered my other wiring questions earlier, and I now have things pretty well sorted out. I also have copies of the wiring diagram that I got from a link provided by a forum member.

The truck is a 1974 F100 XLT 2WD, originally 302, now 351W, 3 speed manual.

First question: In the picture that shows the two fusible links (Orange is 16 gauge, and Yellow is 14 gauge …I snipped them from a salvage truck), is the “fusible” part the thick black plastic section, or is it actually the wire itself between the eyelet and the thick black plastic section?

Second question: In the picture that shows the wires from the solenoid, notice the red wire that has been crimped in with the yellow plastic crimp. That wire goes into a wrapped harness that runs to the alternator, and to the voltage regulator and horn. Should that red wire be a fusible link? I’m assuming that someone replaced it with plain wire. (FWIW, I’m guessing this “repair” was done some time ago, and I think whatever electrical problem existed has been resolved.)

Third question: Assuming that red wire should be replaced with a fusible link, what gauge should it be? I can’t figure this out for sure from the wiring diagram. I assume I can use one of the 16 gauge or 14 gauge links shown in the first pic? I would like to solder the link in place and cover it with shrink tube so it looks nice. Can I remove the red wire, and then solder a fusible link in place where the yellow crimp is now?

Thanks for answers or other suggestions.

 

So, it depends on what gauge of wire is in the harness, as to which fusible link that you use.

 

I believe that the wire between the terminal and thick "fuse-able link" cover is the part that melts away. Its been a long time since I had this problem.

 

Thanks Jklnhyd and JD Q. Any ideas as to how I can determine the gauge of the wire in the harness without removing insulation? Or can someone look at the fusible link for their harness to the alternator and voltage reg? Judging from the stub of black wire going into the yellow plastic crimp (in my second pic), the link looks to be about the same size as the 16 gauge link. But I'd like to do better than a guess. Thanks.

 

The alternator plays a part in this. Are you using a original alternator or a G3?
I found this @ https://www.fordf150.net/forums/viewtopic.php?t=93813
For a 70 amp alternator, a 12Guage fusible link should be used.
"Fusible link wire is color-coded. The standard alternator for a '95 F150 is 95A (4 holes between each pair of ribs on the face), and it uses a single gray fusible link wire. The optional alt is 130A (2 holes), and it uses 2 gray fusible links."

also see https://www.ford-trucks.com/forums/1...ator-fuse.html

 

The alternator is stamped 15V 38A D3ZF 10300 AA NEG. I'm sure they were a lot lower current in the 70s, and I assume mine is only 38 Amps. I believe D3ZF indicates a date of 1973, which I'm guessing might be original to my 1974 truck.

I'm guessing I might only need the 16 gauge link shown in my first pic. Does this seem reasonable? I'll cut the 16 gauge to see if the wire looks to be about the same as the stub that goes into the yellow plastic crimp.