Fusible Links: Keep or replace?

[idM1028]

I've been thinking this over for a while, but feel I could use a second opinion (or five). Before I get started, I understand the CUCV's have fusible links. I understand that the fusible links are designed to act like a fuse and are there to keep electrical stuff in the circuit from frying. Here's the problem I've been having: The fusible links in the truck don't seem to want to do their job. I've had about two or three wires under the hood fry before the fusible links have popped (to include the red wire that runs off the 12V junction block to the fuse block) To me, this seems rather redundant. Whats the point of having fusible links when the wire itself fries first? And what does a fusible link look like when it pops? Is it even possible to visually tell if its gone bad? It seems to me if the wire wants to fry before the fusible link does, why not just get rid of the fusible link and replace it with a regular old wire? Any thoughts?

 

[steelandcanvas]

I can't answer your questions specific to CUCV's, but I am familiar with automotive wiring. That fusible link is protecting something downstream, I don't advise getting rid of it, and installing a plain piece of wire. The do come in several different amperages, maybe the incorrect one was installed. A fusible link most times will not visually give you an indication it has blown, but a continuity tester or digital meter will. Continuity: GOOD no continuity: BAD. See if you can find a schematic and trace it down to that fusible link, hopefully there will be a specification for that link. Hope this helps. Someone may chime-in with some specs on that link.

 

[SGT Estum]

You probably have a bit of a compound problem going on here:

1. You've got something putting out too much power or consuming too much power or a short. This is causing your wire to melt.
2. The fusible link in question is not working correctly.

Fix both of these. For #2, someone my have replaced a fusible link with the wrong type/length of wire causing it to allow much more current through before failing. That, and/or the wire connected to the fusible link my be out of spec (like lighter wire than is called for).

If you replaced the fusible links with fuses or other wire, you would only be masking the real problem and causing yourself more headache in the long run.

 

[papercu]

I think Kenny just posted the sizes the other day. Wayne
http://www.steelsoldiers.com/cucv/70281-m1008-meltdown-2.html

 

[idM1028]

I don't think the fusible links are out of spec. They look to be the original ones that came on the truck (black plastic cylinders). I wouldn't be surprised if the wiring needs to be replaced though. A lot of it looks pretty dry and brittle. Right now I'm pulling my hair out over electrical issues and I'm trying to identify what needs to be fixed and fix it (and if I can "bulletproof" anything along the way, all the better.)

 

[AMX]

I have seen dead shorts burn wires into before the factory fusibile links burned. It may be due to the nature of a fusible link working somewhat like a time delay fuse.

 

[Woodsman]

Has anyone used those plug-in fusible links? They look like a larger version of the fuses in the main fuse box, but these are in-line. From what I have looked at once you wire in the fusible link holder, you then insert the fusible link itself into the holder. Then if one burns out, you can visually look at it and pull it out and replace it in minutes. This seems like preferable option, but wanted to get some input on it.

 

[Wildmax]

Go to Ron Francis wiring website, and read page 97 in his catalog and see what he has to say about fusible links. An eye opening opinion from a guy who is premier in the automotive wiring specialists. http://www.ronfrancis.com/inforequest.asp

 

[idM1028]

So far things seem to be adding up against the fusible links. After cleaning up some electrical contacts and what-not under the hood, I go to hook the front battery up. Small spark, looks like it came from GEN2. I get the clamp on. Hook up positive on the rear battery. Small spark, looks like it came from GEN2. What the???? I start the truck, no problems. Run it for a minute and shut it off. Check the wiring on GEN2 in case I hooked it up wrong. Nope, hooked up fine. I check a orange wire coming off the positive stud (which, sure enough, isn't in the TM) It has a fusible link. The fusible link has a small piece of metal sticking through. ???? My first thoughts are 1.) Was this grounding out on the case? and 2.) Did I just blow this fusible link? I won't have any way of knowing until tomorrow. I'm going to have to trace this wire and find out if its still good or if I blew that link.

 

[doghead]

Do you mean this orange wire/fusible link? (in the diagnostics circuits schematics)

The schematics are broken down into separate types of circuits. You need to look at more than one, to find everything.

 

[idM1028]

Yep. That's it. Sorry I didn't look closer. I was looking at the charging diagram and it honestly didn't make sense to me to that wire wouldn't be in that diagram. I forgot that the alternators are part of the diagnostics circuit. I should know better since I was trying to figure out what the black and white wire from GEN1 went to the other day. Speaking of diagnostics, whats the opinion on yanking that stuff (or at least the plug and wiring) out of the truck? I don't even think the equipment to run a test on it is around anymore and to me it just seems like its cluttering up the wiring. I know the truck will no longer be "original", but I'm willing to give it to anybody that needs it.

 

[Warthog]

Just rip it all out and start from scratch.

 

[idM1028]

Just rip it all out and start from scratch.

Trust me, the idea has crossed my mind more than a number of times. The truck is my one and only daily driver for the time being so I need it be reliable. Right now precious time to work on the truck is in short demand, so I'm pretty much just patching up bullet wounds instead of yanking out the slug.

 

[Jones]

The biggest complaint against fusible links is that they aren't readily detectable as good or bad... and that's if you know they're there. If you're not expecting them, they can be a real nightmare.
Also, they're usually wired in (not quick change) and how many of us carry a spool of fusible link material with us.

What about replacing them with inline fuses, or my personal favorite; circuit breakers?
Breakers can be had in manual or automatic resetting types. Like a glass BUSS fuse, they can be spotted as good or bad/tripped or set at a glance.

 

[Recovry4x4]

I think the advantage to link wire is that it can take surge loads better than fuses or breakers. Rule of thumb is that they are 4 wire sizes smaller that the main wire. If the integrity of the main wire is compromised, I could see the link wire not working. I'm wondering if truck may have been submerged?

 

[SouthernSteel]

With all Thats been said about fusible links i have thought about that before any suitable upgrades i mean my m1008 gets drivin daily.Where are yall getting Engine harnesses to replace the old ones or are yall making them yourself with wire which i have thought about doing but i havent got a clue where to begin to even try that as i know u can get new headlight harnesses but i have never seen new engine harnesses

 

[bkwudzhom]

I would LOVE it if I could get a fresh wire harness!
I have printed all of the schmatics and laminated them.