# Electrical problem 1991 D21 Nissan pickup



## stipesman (9 mo ago)

I was driving Nissan pick up and suddenly I smelled electrical burning (heater, lights radio were on) then the heater, radio taillights stopped. When I got home, (the truck still starts and runs and the headlights and windshield wipers work) I checked what worked and didn't. the taillights, interior lights, radio, heater, signal lights, dash light and gauges, do not work. Any ideas what this could be? I checked the fuses under the dash and none of them were bad so I am a bit confused. I did replace the light switch assembly about 3 or 4 months ago.


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## VStar650CL (Nov 12, 2020)

Is the truck charging? If not, you probably blew the black fusible link coming off the battery. If it is charging, you burned up a section of the fat white wire coming off that link and connecting to the fusebox.


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## jp2code (Jun 2, 2011)

Another thing to check is a trailer wiring harness. If your truck has that, crawl under the truck, pull the electrical tape off, and you will likely see that they almost fall apart. If the power wire touches ground, it will kill a lot of systems on the truck.


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## stipesman (9 mo ago)

VStar650CL said:


> Is the truck charging? If not, you probably blew the black fusible link coming off the battery. If it is charging, you burned up a section of the fat white wire coming off that link and connecting to the fusebox.


Just checked and the truck is not charging.


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## stipesman (9 mo ago)

stipesman said:


> Just checked and the truck is not charging.


Could a failure of the alternator cause this?


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## jp2code (Jun 2, 2011)

stipesman said:


> Could a failure of the alternator cause this?


That could be a burned black fusible link, a bad alternator, or a bad voltage regulator (built into the alternator).

If you can get the truck to an auto parts store, they will run a free alternator test for you.


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## stipesman (9 mo ago)

jp2code said:


> That could be a burned black fusible link, a bad alternator, or a bad voltage regulator (built into the alternator).
> 
> If you can get the truck to an auto parts store, they will run a free alternator test for you.


yup, the black fusible link that is next to the green one, is burned and open circuit. I will replace but I am wondering if there is something external that could cause this fusible link to fail? Hopefully when I replace, everything will work again, including charging, but I am a little nervous thinking there might be something going intermittently wrong and it will happen again.


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## VStar650CL (Nov 12, 2020)

That link carries all the charging juice from the alternator, so if the alternator has a shorted stator winding it will blow the new link. The same will happen if you have a short circuit someplace between the alternator and fusebox. I'd get two links and disconnect the alternator output wire before replacing it, then briefly run the truck to see if the new link blows. If it does then you know there's a short in the wiring, if it doesn't then you know it's a failed alternator.


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## jp2code (Jun 2, 2011)

stipesman said:


> yup, the black fusible link that is next to the green one, is burned and open circuit. I will replace but I am wondering if there is something external that could cause this fusible link to fail? Hopefully when I replace, everything will work again, including charging, but I am a little nervous thinking there might be something going intermittently wrong and it will happen again.


When the alternator is going out, sometimes it charges, and sometimes it doesn't. This can cause brownouts in the electrical system.

When the voltage regulator goes out, sometimes large electrical spikes can jolt through the electrical system.

Whenever someone tries to jump-start the truck and they put the jumper cables on backwards, there is a surge that goes through the electrical system.

The fusible links are designed to burn into in any of those scenarios so that those electrical problems do not get to your injectors or ECU.

Any number of things could have caused a fusible link to go out. I wouldn't worry too much about it unless it burns out again.

Fusible links are getting hard to find, but you should be able to find fusible link wire. Someone told me once that they are categorized by their color, so look for some black fusible link wire on Amazon if the dealership doesn't have anything.

If it burns out again, I'd suspect the alternator first. It has the Voltage Regulator built into it. But get a new one, not a rebuilt.


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## VStar650CL (Nov 12, 2020)

jp2code said:


> Fusible links are getting hard to find, but you should be able to find fusible link wire. Someone told me once that they are categorized by their color, so look for some black fusible link wire on Amazon if the dealership doesn't have anything.


+1. The OP could also crimp on some ring lugs and replace the wire link with a modern screw-in type like this. The Black links are 80 amp:


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## VStar650CL (Nov 12, 2020)

For everyone's future reference, these are the color codes:


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## stipesman (9 mo ago)

thanks, you all are great~!!!!!


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## Turdfinder (Apr 21, 2021)

stipesman said:


> I was driving Nissan pick up and suddenly I smelled electrical burning (heater, lights radio were on) then the heater, radio taillights stopped. When I got home, (the truck still starts and runs and the headlights and windshield wipers work) I checked what worked and didn't. the taillights, interior lights, radio, heater, signal lights, dash light and gauges, do not work. Any ideas what this could be? I checked the fuses under the dash and none of them were bad so I am a bit confused. I did replace the light switch assembly about 3 or 4 months ago.


Check the dimmer switch in your dash had mine burn up


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## stipesman (9 mo ago)

stipesman said:


> thanks, you all are great~!!!!!





VStar650CL said:


> That link carries all the charging juice from the alternator, so if the alternator has a shorted stator winding it will blow the new link. The same will happen if you have a short circuit someplace between the alternator and fusebox. I'd get two links and disconnect the alternator output wire before replacing it, then briefly run the truck to see if the new link blows. If it does then you know there's a short in the wiring, if it doesn't then you know it's a failed alternator.


I just bought a new fusible link and went to hook up battery and when terminal touched, it arced with serious short. Alternator? I replaced the alternator a few months ago with a rebuilt one. Could that be cause, a failed alternator? I am going to disconnect alternator and see if short still exists.


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## stipesman (9 mo ago)

UP date. Tested with alternator disconnected completely and still have sharp arc when I try to connect positive terminal so there has to be a short somewhere. Would it be the wiring? Seems funny in that when this failure occurred I was driving along fine with all the accessories on and then the failure occurred with no fuse failures that I can see. So somewhere in the electrical system that has hot electricity without key on has to have a short. I looked at all external wires under hood that I could and so no signs of shorting


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## jp2code (Jun 2, 2011)

stipesman said:


> I just bought a new fusible link and went to hook up battery and when terminal touched, it arced with serious short. Alternator? I replaced the alternator a few months ago with a rebuilt one. Could that be cause, a failed alternator? I am going to disconnect alternator and see if short still exists.


Rebuilt Nissan alternators and alternators have bad luck for some reason. My theory is that Nissan's electrical motors last so long that they go bad because the shafts inside actually wear down. When electrical shops rebuild alternators and starters, usually they just clean the motors and replace the contacts. And you still have a worn out shaft that wobbles around inside. For old Nissan, Toyota, and Honda, I'd always recommend getting something new.

Back to the fusible link that probably just burned up. You need to find out what is shorting out. Watch this video:









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## stipesman (9 mo ago)

jp2code said:


> Rebuilt Nissan alternators and alternators have bad luck for some reason. My theory is that Nissan's electrical motors last so long that they go bad because the shafts inside actually wear down. When electrical shops rebuild alternators and starters, usually they just clean the motors and replace the contacts. And you still have a worn out shaft that wobbles around inside. For old Nissan, Toyota, and Honda, I'd always recommend getting something new.
> 
> Back to the fusible link that probably just burned up. You need to find out what is shorting out. Watch this video:
> 
> ...


I have more than a slight parasitic draw, when I connect the battery, it will burn the 80 amp fusible link so there is a direct short of a hot lead that is not fuse protected. I am going to start another thread on this problem, thanks.


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## VStar650CL (Nov 12, 2020)

That dimmer switch that @Turdfinder mentioned is a good possibility, or a shorted blower motor.


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## jp2code (Jun 2, 2011)

The injectors get their power directly from the fusible links. If one of those were melted, your fusible link would burn out as soon as it were connected.

On the parasitic draw video, the point wasn't to look for a parasitic draw but how to systematically go through your electrical system to find where you have your short.


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## VStar650CL (Nov 12, 2020)

VStar650CL said:


> That dimmer switch that @Turdfinder mentioned is a good possibility, or a shorted blower motor.





jp2code said:


> The injectors get their power directly from the fusible links. If one of those were melted, your fusible link would burn out as soon as it were connected.


See the IP's new post about this. He's right, no fuses are blowing downstream, and the smaller links and fuses would blow before the 80A link if the problem was in an individual system or component. So with disconnecting the alternator not helping, the problem has to be in the big White wire which is fed by the 80A link. Most likely a chafed harness.


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