fussible link / electrical

[efftwofifty]

Just bought a 72-camper special [auto/390] basket/project…and trying to trace an electrical problem…In beginning the process I noticed that the ignition had been hot wired and the fusible link fried.. I believe that in the process of putting in a new battery the previous owner nicked the wire from the relay to the alternator and shorted the fusible link

I am not entirely clear on how/what to replace the fusible link with…[20A in line fuse?]...or where to find one.. it is nor something that is stocked that the local quickie auto.. And the pimply teenagers only seem to know about stereos and spinners.. Thoughts? Thanx in advance

[72f100]

I'm not sure what the gauge of your wire is, but on my 72 (F-100 w/ 302)it was 16. I found the fusible link at an auto electronics store. The guy who was running the store gave very detailed instructions. Just cut out the old one and solder in the new one.

[flyboy2610]

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[Ford_Doctor]

I'm sure, or a least hope, that this problem has been repaired. But, just for future reference your local NAPA has or can get various gauges of fusible link.

[bluef250]

In looking at the electrical schematics, I cannot find where Ford installed fusible links in the 67-72 trucks. Since this questions comes up occasionally, I wonder if someone has researched the question. On other sites, the recommended fusible link is 2 sizes smaller than the wire it protects 12 link for a 8 awg wire, 14 link for a 10 awg, etc. Some like the fusible links, others not, preferring to use a circuit breaker. The links can fail rather dramatically, and possibly start a fire.

[68F250]

The fuse link is part of the wire that goes from the alternator output (+) to the plus side of the starter solenoid which the battery is also connected to. The regular wire from the alternator (#38 ) comes to an end and is soldered to the wire for the ammeter tap (#38A) which then comes to an end and is soldered to the fuse link wire (#38B) which finally continues to the solenoid. It's all taped up in the harness so you can't see it until it melts everything! I think fuse links started in '69, you won't find a wire #38B on earlier diagrams but instead you'll see that wire #38 or 38A is the one that finally connects to the solenoid.

[Ford_Doctor]

Well I've been a Ford technician now for 10 years and never have seen any dramatic failures of fusible links. When a fusible link failure occurs it is very hard to locate. The worst I have seen is some discoloration of the link insulation but usually you need to check the continuity of the wire or pull on it and see if it stretches indicating a break. I don't know about the links in pre '69 trucks but I rewired my engine compartment and have the links connected directly to the starter relay, one for the alternator and one for the feed to the fuse panel. This is the way Ford did it on later vehicles, and I wouldn't recommend taping it into the harness.