Fusible link

[Thomas Perkins]

Is the wire at the fusible link that goes to the lights burn up the wire in time?My Headlights awhile back stopped working.Brand new head lights.I checked the connections and they were good.Then I checked the fusible link and one wire was melted.I replaced and it fixed it.It happened before about 3 years ago.I bought 2 fusible links back then,I always buy things in two's.,I still have a brand new one.I think it was Nissan's last fusible links that they had,even bought the 2 last metal pieces that go to them that connects to the battery.I was able to fix the last one without having to replace it.I guess the light wire has a lot of juice going thru it.My fan fuse use to pop out a lot.Not anymore,I had my system rewired,passing that fuse.When I got the new heating and air system installed,he rewired it and I don't use the fuse that was used for the heating and air.The fuse area that holds the fuse was melted.Another thing you will not believe,the 10 amp fuse won't work for the coil.I have to use a 30 amp fuse.Been that way for 27 years,came that way,I put a 10 amp fuse in it and it wouldn't work,took to a specialist and they didn't figure it out.So the 30 amp fuse stays in there.

Edited December 5, 2021 by Thomas Perkins

[datzenmike]

They are protection for the wire traveling to the fuse box. The headlights have their own fuses. In an accident the wire from the battery to the fuse box could be pinched and grounded. Then, unlimited current would try to flow down the wire heating it up like an electric toaster and a fire would be the result. They don't burn up unless there is a severe draw of power exceeding the fusible links rating. In this case a Green coded wire. 40 amp.

 

 

 

[Thomas Perkins]

My fusible link has one black wire going to the alternator,which is connected to a thick white wire.I have 2 green wires and two red wires on the fusible link.The red and green wires look perty much the same.But my lights did quit working and the red wire was burned up and I fixed it and the lights started working.I can take a picture of it but it is dark.I know they have fuses,but they were good.Long ago,the connectors that the fusible link connects to were goners,so I replaced them with wire fittings.Where the red fitting connects in the fusible link which has the plastic covering over the metal fittings,it melted the plastic piece and the two metal pieces were no longer making connection,so I got my box cutter and trimmed the plastic off and replaced one fitting and reconnected them.It was about the time my alternator was over charging,and it was causing my relays under the glove box to make clicking noises and it kilt the battery,I took and had alternator tested while my truck was running and it read 15.6 volts and a couple of days later the alternator went to 12 volts and I replaced it.Maybe this caused it.I will go take a picture of the part I fixed,This is my new fusible link and the yellow connectors is what I used to replace the original connectors.The other 4 wires are white,2 with red stripes and 2 with green stripes.

 

Edited December 5, 2021 by Thomas Perkins

[Thomas Perkins]

Here is the power supply picture from my 85 Nissan Service manual.If the red wire coming from the fusible link is burnt and not supplying power to the fuse box with the fuses for the headlights,then the lights will not work.That is what happened,the fusible link wire melt and stopped the flow to the 2 light fuses in the fuse box.All 720's power supply is not the same.I also have a Haynes book and it shows different years in different ways.I can go and disconnect that red wire and the lights will not work.The red fusible link sends power to the headlight fuses.

[datzenmike]

 The headlights are protected by a Green fusible link. Follow the Red wire (NOT a fusible link) from the fuse box back to the battery and it connects to the Green fusible link. The Green fusible link is to protect the Red wire.

[Thomas Perkins]

I just check out my wiring on my fusible link and I had some in the wrong place,yes you are right. When I disconnected the red wire,my lights would not come on,I had that wire in the wrong place.The red wire connects to the single green fusible link,I had to change the end fitting to a female end.The black wire and a green wire fusible link is connected to a white wiring going to the alternator and the green wire is connected to a white wire with a black stripe.The double red fusible link has a white wire with a red stripe and the other is white wire with a green stripe.They are all in the right place now.That is why my red head light wire melted cause it was in the wrong fusible link.So now my stereo is working right,I just reset the channels and set the time.Some of the buttons were not working,now they are,I guess it was not getting enough power.I also had to change another fitting to a male.Thanks mike.I am fixing to take it for a ride.

Edited December 5, 2021 by Thomas Perkins

[datzenmike]

That's much betta.