1984 Dodge D350 pickup, 360 motor with 100 amp alternator. When the motor is running one of the fusible links gets really hot. I have replaced the alternator and voltage regulator and nothing has changed. There are two small wires that connect to the back of the alternator. An orange or faded red wire and what looks like a pale green or yellow wire. When these two small wires are unplugged the link does not get hot. Do these wires connect to the voltage regulator? Will the battery not charge if these are left unplugged?
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Re: Fusible link wire gets really hot.
Removing the two smaller wires stops the exciter current to the alt which stops it charging.
Usually if a wire is getting hot its because:
A: Current overload..
B: Corrosion in wire restricting current.
C: Corroded terminal.
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A fusible link is basically a fuse built into a wire. It is designed to burn up whenever too high of an amp load is placed onto that circuit. If you have burned one up you will need to find out where the amp load came from and then replace with another fusible link of the same rating.
IF your car even has a fusible link it will be on the positive battery cable which goes to the alternator. Make sure you disconnect the negative cable from the battery also when you go to remove the positive cable. This is also a dealer item so you'll have to go to FORD to buy the new cables which they usually only sell as a set. Be prepared to pay $75 - $100 for the cables.
If the fusible link is blown, I'd suggest testing the Alternator to make sure it isn't over charging or spiking, that fusible link should be good for about 175 amps so it really shouldn't blow unless there's another problem like a faulty regulator.
There should be 2 white wires coming from the alternator. There is a splice where it will go into 1 wire then into the fusible link. If the fusible link is not burned, simply match the gauge wire coming from it. You should never use anything smaller in diameter than 10 gauge wire for the charging system. If you want to replace the fusible link, you can run separate white wires from the alternator to the positive battery post with individual fuses or fusible links. I would recommend each wire have its own Maxi fuse holder with a fuse no less than 60 amps each.
The fuel pump relay is powered by a fusible link connected to the starter solenoid on the positive battery terminal. That fusible link feeds the 10 amp fuse near the relay. You can test the fusible links with a 12 volt test lamp. If the fusible link test okay check for an open circuit in the wire between the link and the 10 amp fuse. Hope this gets you fixed.
Fusible links work much differently than blade fuses, they can tolerate a large load without melting, this is why they are used for high amp draw systems. You can't substitute the blade fuses, they will blow repeatedly if you do. Fusible links are very cheap and all auto parts stores have them, they go by color to indicate what the amp rating is, wire gauge is not used. So the bottom line hear is you can use blade fuses but they will likely blow often, you will need fusible links (Green) or 30 or 20 amp fuses. Here is the color breakdown of all fusible links.
It most likely is a fusible link on the starter,connect a large wire(better to be larger than the one that is on there already)to the back of the alternator and go to the positive side of the battery,or to the starter hot post,where the battery positive cable connects to the starter,this will take care of the problem,no fusible link will be needed.The fusible link really hinders the charging capacity to the battery and running of the engine,cause it carries less amps in the smaller fusible link wire,this will solve the problem most likely.
Sounds like fusible link. It's a thick (thicker than normal) wire coming from battery to junction block on firewall. They burn through and/or break down internally - you can replace it with an inline 30amp fuse & holder.
Check the battery + wire at the alternator to be sure it is 'hot'. If not, the alternator can not charge. If you suspect a short, check all the fusible links. Pull on each one, as I have seen many that have a burned or broken conductor but the outer insulation is not burned open. (You can buy fusible links and fusible wire to make your own)
Ammeters on your vintage Dodge are notorious for failing, and for being inaccurate. Just in case yours failed internally, jump the 2 wires together, (The gauge will then not work), but if it charges now you know its open.
But check out the alt power feed first, as well as the fusible links and I bet you'll find the problem.
Fusible link should be available at any full service Auto Parts supply available on a roll which you purchase by the inch. Do not replace the fusible link with a piece of #10 stranded wire. Have you checked with your local GM garage for this link?
You say the fusible link is rated @ 20 amp's @ 12 V dc, I would suggest you could put a auto-resetting 20 amp @ 12 V dc circuit breaker in its place but not a wire.
Fusible link rarely "blows". I think you should find the cause before you go much further.