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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

My alternator wire burned completely off!

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Old Oct 24, 2006 | 10:46 AM
  #1  
OSIRIS's Avatar
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My alternator wire burned completely off!

the wire on the alternator that goes to the battery is burned off at the connection with the alternator?

Time for a new alternator?

or

Time for the 'big 3 or 4' wire upgrade?

All the above?

Last edited by OSIRIS; Oct 24, 2006 at 01:13 PM.
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Old Oct 24, 2006 | 10:58 AM
  #2  
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Sounds like a lot of current was getting pulled... were you running a lot of accessories, or do you have a short somewhere? Big 3 Upgrade could be an option, but you should figure out what CAUSED this first...
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Old Oct 24, 2006 | 11:26 AM
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Burned off huh, got any pics of that?
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Old Oct 24, 2006 | 12:30 PM
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probably was a poor connection, got a little corrosion, resistance of connection got higher, resulting in more heat, resulting in faster corrosion, heat, corrosion, heat, corrosion, until it was all over. Probably worst right after startup when alt output was high to recharge the batt.
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Old Oct 24, 2006 | 12:36 PM
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Originally Posted by mastacox
Sounds like a lot of current was getting pulled... were you running a lot of accessories, or do you have a short somewhere? Big 3 Upgrade could be an option, but you should figure out what CAUSED this first...
I agree, I need to find the source of the problem and fix it. I had the engine swapped out and perhaps this is an effect of something they missed. Could this happen if the engine to chassis ground was not connected or broken since then. I do not have any accessories yet. I have a stereo to install, but I was waiting until I was able to solve this problem first. The batt light came on and then went off sparatically over the past couple of weeks and I looked at the wires and there was nothing to see out of the ordinary. Today the batt light did not turn off but at least I made it to work! Getting home - another story.

Ok so, for the wire to fry itself at the base of the alternator that is a sign of current being pulled out of the alternator? I do not think it was the regulator frying and causing too much voltage to flow because I would have seen that on the meter in the car and did not, so I think you are on the right track that it was current. Having a bad ground would cause more current to be pulled?

She runs fine, no sputter with this problem.
Thanks for your help.
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Old Oct 24, 2006 | 12:47 PM
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From: Dayton, OH
poor ground=less current.

batt light was coming on because the connect was so wasted the batt was not getting sufficient charge from the alt anymore. Unless you have a batt with internal plates shorted, there was no over current condition. the stock allt can oly put out 65 amps anyway.
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Old Oct 24, 2006 | 12:48 PM
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Then how would it get so hot to burn off that connection like that?
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Old Oct 24, 2006 | 01:10 PM
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From: Dayton, OH
because any current across a resistance make s heat. If you had a poor connection, there's some finite resistance there. That resistive connection probably got hot. Heat increases chemical processes, including corrosion. You can see the "vicious cycle" emerging here. FWIW even just 10 amps will generate some serious heat across even a relatively small resistance.
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Old Oct 27, 2006 | 05:40 PM
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From: Pleasanton Ca
Usually poor connections cause a certain degree of arcing, depending on the amperage and voltage of the circuit. The arching usually melts the insulation (and sometimes the wire) and chars the connection.
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Old Apr 16, 2009 | 05:47 AM
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Not the alt-battery wire, ....

Originally Posted by OSIRIS
the wire on the alternator that goes to the battery is burned off at the connection with the alternator?

Time for a new alternator?

or

Time for the 'big 3 or 4' wire upgrade?

All the above?
On my truck, a '94 4X4 Auto Trans, the wire from the alternator to ground (terminates on alternator mounting frame above) burned this morning, during a failing attempt to start. It would turn over very sluggishly, then not. I happened to peek out the front, and I saw smoke coming out of the driver side front of the hood. Of course I was suspicious, knowing that the battery is on the other side, so I got out and looked. The wire that is fastened to the adjustable mount for the alternator and goes down into the loom directly below the steering knuckle boot was fried.

Is this the alternator ground wire? I assumed it was so, because what else would be grounded there? And if it is, should I assume that the battery is fine, and just replace the wire in question?

Thanks,

Shane
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Old Apr 16, 2009 | 05:56 AM
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From: Oklahoma State
Originally Posted by NassauBob
On my truck, a '94 4X4 Auto Trans, the wire from the alternator to ground (terminates on alternator mounting frame above) burned this morning, during a failing attempt to start. It would turn over very sluggishly, then not. I happened to peek out the front, and I saw smoke coming out of the driver side front of the hood. Of course I was suspicious, knowing that the battery is on the other side, so I got out and looked. The wire that is fastened to the adjustable mount for the alternator and goes down into the loom directly below the steering knuckle boot was fried.

Is this the alternator ground wire? I assumed it was so, because what else would be grounded there? And if it is, should I assume that the battery is fine, and just replace the wire in question?

Thanks,

Shane

A pic might help. Was the connection loose maybe?
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