fusible link keeps blowing

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meatloaf

meatloaf

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So. Austin, tx
fusible link keeps blowing... my brother 83 fj60 has a short somewhere. His fusible like went out last week, replaced it and it went out again tonight. he was driving it and said he heard a pop, followed by a burnt smell and the a sound similar to squeeling belts, we looked at it ((already night though)) but you can see where the fusible link burnt on the black wire. Is there anything I specifically want to look at? Lights are on but truck wont start, so I am assuming that the black wire (and short) are on the the starting system.

Any ideas?

Thanks,
ML
 
Belt noise would lead me to start with the Alternator. Is the fusible link from the alt wire?
 
the black fusible link goes to the ignition switch to power keyed accessories, the ignition circuit and the low amp side of the starter. Most of the accessories have addtional fuses, so I would start with the ignition and starter circuits. If it's intermittent you might have to run new wires to and from the switch. It's not like you can disconnect the ignition or starter and still run the truck.
 
would suspect the alt or starter. Unless you have performed some electrical repair recently. You have a direct short to ground somewhere most likely. Make sure nothing was recelty replaced or "re-worked" that would cause this. I let the smoke out one time becuase I was trying to figure out how to integrate a GM alternator with Toyota wiring harness and I had teh connections wrong for a few seconds too long.
 
at this point, I would guess the short is at the starter... for a while, my brother was having to strike the starter with a piece of pipe cause it wouldnt crank over. I can see visible gouges at the front of the starter... The alternator vas tested by Oreilly's the first time the link blew and it checked out ok. Time to start tracing wires...
 
My key would stick on the crank (start)position and fried starters and fuse links I tossed the rekeyed key and it stopes stickin I also replaced the link with fuses cause it keeped popin them cause the plug was bad too. Ck the inside of the plugs make sure they're not dark or black
 
HELP!!!

So the saga continues... we replaced the starter (cause it was messed up), and did what Kling-On did - installed three 30amp fuses instead of the fusible link. The fuse from the alternator keeps blowing. it seems when lights were turned on and truck was accelerated, the fuse would blow. any other suggestions other than tracing the alt wire back to the dash. anything in particular to look for?

Oh, and the alternator checked out good, 2X at Oreilly's.

Thanks again for the help...
meatloaf
 
you guys have not installed anything recentely that in any way would interact with the wiring...even screws or bolts might pierce the wiring harnes ? Nothing was removed and then reinstalled electrically?

What happens if you disconnect the ALternator and then turn on switch, do the fuses blow still?
 
The entire electrical load on your truck comes from the alternator once your engine is running. So, a 30 amp fuse in line with your alternator is way too small. Your alternator is supplying charge current for the battery as well as everything else. I'm surprised it doesn't blow immediately. Put a fusible link back in there, or go with something like a 60 amp slo blo fuse designed for that purpose. You may have fixed your original problem when you replaced the starter, and now have introduced a new problem with a fuse that is too small. I would especially suspect this if you never blow the 30 amp fuse that you have in place of the fusible link until you turn on the headlights.
 
Elbert said:
you guys have not installed anything recentely that in any way would interact with the wiring...even screws or bolts might pierce the wiring harnes ? Nothing was removed and then reinstalled electrically?

What happens if you disconnect the ALternator and then turn on switch, do the fuses blow still?
Click to expand...


Nothing installed that I know of... I know he did do the horn contact clean but that is about it.

I will try unplugging the alternator tonight after work...

Thanks Elbert!
 
slcfj62 said:
The entire electrical load on your truck comes from the alternator once your engine is running. So, a 30 amp fuse in line with your alternator is way too small. Your alternator is supplying charge current for the battery as well as everything else. I'm surprised it doesn't blow immediately. Put a fusible link back in there, or go with something like a 60 amp slo blo fuse designed for that purpose. You may have fixed your original problem when you replaced the starter, and now have introduced a new problem with a fuse that is too small. I would especially suspect this if you never blow the 30 amp fuse that you have in place of the fusible link until you turn on the headlights.
Click to expand...

SLCFJ62,

What you write here makes sense but we tried it with lights on/off and it blows the fuse, mainly when accelerating. At first we had to jump it to get it started. Also, at first we could see a little 'flash' behind the instrument panel when the fuses would blow. pulled off instrument panel, ac contol panel and saw the flash a couple more times as the fuse blew but could not pinpoint the actual location. could not see the flash after a while, maybe we moved something around... I did place a voltmeter across the alt 30 amp fuse and it read 12 volts at idle, when the eng was reved up, it went to 13V and then spiked to 28.3V when the fuse blew withing 5 seconds.

thanks,
ML
 
are you saying Alt voltage hit 28 volts? High end would be somewhere around 14?

the truck you are talking about is not a 24 volt setup is it?
 
meatloaf said:
SLCFJ62,

What you write here makes sense but we tried it with lights on/off and it blows the fuse, mainly when accelerating. At first we had to jump it to get it started. Also, at first we could see a little 'flash' behind the instrument panel when the fuses would blow. pulled off instrument panel, ac contol panel and saw the flash a couple more times as the fuse blew but could not pinpoint the actual location. could not see the flash after a while, maybe we moved something around... I did place a voltmeter across the alt 30 amp fuse and it read 12 volts at idle, when the eng was reved up, it went to 13V and then spiked to 28.3V when the fuse blew withing 5 seconds.

thanks,
ML
Click to expand...

28 volts is a problem. Unless you have a 24 volt system, the only way you can get 28 volts is if the alternator is defective. At 28 volts, you will be blowing out light bulbs, so the flash you saw could have been that, or, if it was dark, the flash could have been a short manifesting itself. Sounds like you've got a real exciting one going.
 
:eek:
meatloaf said:
. and then spiked to 28.3V when the fuse blew withing 5 seconds.

thanks,
ML
Click to expand...

THAT SOUND WAY HIGH :eek: I ran mine for years with the 30amp fuses in it ... but I alway wonder the same about the alt fuse :meh:
 
Elbert said:
are you saying Alt voltage hit 28 volts? High end would be somewhere around 14?

the truck you are talking about is not a 24 volt setup is it?
Click to expand...
Elberts, yes, the truck hit 28.3V at the alternator fuse, just then the fuse opened. It is not a 24V system...

slcfj62 said:
28 volts is a problem. Unless you have a 24 volt system, the only way you can get 28 volts is if the alternator is defective. At 28 volts, you will be blowing out light bulbs, so the flash you saw could have been that, or, if it was dark, the flash could have been a short manifesting itself. Sounds like you've got a real exciting one going.
Click to expand...

SLCFJ62,

Lightbulbs are ok... I also was thinking a wire arcing somewhere but could not pinpoint where. it was under the dash for sure.

In your other reply, you state that using a 60A lowblow fuse might work because 30A arre too small. I am going to try this but I still think there is a short somewhre....
 
meatloaf said:
Elberts, yes, the truck hit 28.3V at the alternator fuse, just then the fuse opened. It is not a 24V system...



SLCFJ62,

Lightbulbs are ok... I also was thinking a wire arcing somewhere but could not pinpoint where. it was under the dash for sure.

In your other reply, you state that using a 60A lowblow fuse might work because 30A arre too small. I am going to try this but I still think there is a short somewhre....
Click to expand...

Sounds like the alt is a 24 volt unit or something is very wrong with it.

That number of 28Volts is consistant with a 24 volt system.

In saying that, the headlight switch can sometimes be faulty and cause a short, seen this once before.


Rob
 
Radd Cruisers said:
Sounds like the alt is a 24 volt unit or something is very wrong with it.

That number of 28Volts is consistant with a 24 volt system.

In saying that, the headlight switch can sometimes be faulty and cause a short, seen this once before.


Rob
Click to expand...

:idea: Talked to my brother... he did do the 'fix' on the light switch because the brightlights were not working. At the same time, he also "fixed" the contacts on the horn cause it was not working (by putting some small washers as spacers to move the plate up a little so it would make contact).

slcfj62 said:
Based on your symptoms, I'd stick with 30 amp fuses until you fix the short or the alternator. That way you aren't stressing your wires too much and won't be paying for 60 amp slo blo fuses. Then once you get the problem fixed, go with a 60 amp.
Click to expand...

Thanks, I will pull the steering wheel today and look further into this.
 
at oriellys does it ger enough rpms to generate 28 volts? just saying maybe it is the alt but they arent picking up the overcharging cuz it doesnt spin it fast enough..

but i dont know s*** about alt testers
 
YOu should not see 28 volts at your Alt on GAS engine....12 volt setup.

Do you have anyone you can swap out alternators with...for test purposes?
 
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