Fusible Link Size

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CostaricaBJ40

CostaricaBJ40

10 Year 15 Year
Joined
Nov 10, 2006
Threads
5
Messages
55
Location
Costa Rica
Hey All,

I've been searching the threads to try and get an idea of the size of the fusible link to use on my 79 BJ40. The PO has removed it, and it is running with a straight wire, something I want to rectify (along with running the headlights without a fuse).

Instead of going with a fusible link, I was thinking it might be easier to hook up an in-line fuse with the appropriate rated fuse. However, I can't figure out what size fuse that might be. The size of the alternator output? Not sure what size alternator I have, but I'm guessing it will be in the 40-60 amp range, which would be a big honking fuse. Is something that size available as an in-line?

Other options?

Thanks, great site, lots of info.
 
www.waytekwire.com has inline fuse holders with 6ga wire and ATC style fuses for it up to 80 amps. They also carry resettable circuit breakers from 25 to 150 amps. I would use a resettable breaker.
 
Costa...

First assumption: This BJ40 is a 12 volt system and is equipped with an ammeter and has a 40 amp alternator.

The fuse link is really just a piece of wire that has been factory calibrated so that your ammeter reads sort of correct and to protect some of the external wiring in case of a short circuit [not the starter]. The resistance of this wire is on the order of 1 milliohm. It takes a sustained high current (around 100 amps) to heat this wire to red hot and then burn out, literally. This means that it acts like a very slow blow fuse. When you start the cruiser, the alternator dumps a surge current of around 50 amps into the battery thru the fuse link, but only for a couple of seconds; the current then drops rapidly to around 10 amps.

You can put a fuse in place of the fuse link; however, it is of un-known resistance. A fuse like this:
http://www.go2marine.com/product.do?no=21456F

will probably work, but if the current limit of the fuse is approached it may blow when it is not suppose to. A high current fuse with known slow blow characteristics would be what u need to look for. Of course, the ammeter will not read accurately off a fuse system without knowing the meter electronics (internal resistance, etc).

...
 
You can get Maxi fuses up to 80 amps. They are like a very large blade type fuses. I used a fuse block from Walmart, it was made for the super stereo installations, but works for me. You can also use something like this: http://www.electricvehiclesusa.com/product_p/fh-maxi.htm

I'm using a 60 amp fuse currently, and I have also separated out my headlight circuit from the main harness. I use the stock headlight harness to trigger high current relays that switch directly from a fused battery connection. I was able to increase the voltage at the headlights 1-2 volts with this modification. See info on this modification at: http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

Per the suggestion on Mad Electrical, I also doubled up my supply wire up to the dash. You can see the article here: http://www.madelectrical.com/electricaltech/amp-gauges.shtml . You do lose the stock ammeter, but since I upgraded to a 94amp alternator the stock ammeter couldn't handle it either. This doubled up circuit is fed by my 60amp Maxi fuse.

Everything seems to work well, and the voltage drop to the fuse panel as well as to the headlights is greatly reduced.

The 60amp fuse is just a guess on my point at this time, I need to still look at all the potential current draws and size it appropriately.

Hope this helps.

Jeff
 
Thanks dfmorse,

Yes, 12v, and I'm guessing it is a 40Amp alternator. I guess my other option would be to go to the Toyota dealer and see what they have in stock and pricing. the original connectors are long gone, so I was thinking an inline would be the easiest way to go.

Thanks for the input, that is the kind of info I was looking for.
 
if you can get the link from the dealer.........do it! but I know they are a dead part for US 81-83 Fj40's.

I made my own, just used some fusible link wire, took the old conectors apart and replaced.
 
Also, on BJ42s (and I'm guessing BJ40s) there is a little black plastic clip container on the wire to the ammeter that has 2 fuses in it. If these are toast, the ammeter won't work (not that they ever move much), they are either 5 or 15 amp, can't remember)
 
late fj40's have the same.

Voostra said:
Also, on BJ42s (and I'm guessing BJ40s) there is a little black plastic clip container on the wire to the ammeter that has 2 fuses in it. If these are toast, the ammeter won't work (not that they ever move much), they are either 5 or 15 amp, can't remember)
Click to expand...
 
Here' the part # ur looking for:

90982-08071 FUSIBLE, LINK usa spec FJ40.

Keep in mind that u may not have the mating connectors.

I would use a 8 inch piece of #14 ga wire (stranded) for the link; it will be close to stock.

...
 
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