This is topic 3 Alternators in 2 months/500 miles??? in forum Tech Talk at Northern California Ford Owners  .


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Posted by HaulinAss Motorsports (Member # 541) on :
 
1999 Mustang GT
Has had 3 "Quality" Non Kragens Alternators in less than 2 months and maybe 500 miles. First one went out thought no biggie. 2nd one went out thought it was a defect. Today the 3rd one just went out WTF???

This last one only lasted MAYBE 100 miles
Last Friday it started flickering the battery light and the volt gauge was up and down. It was intermittent and at times the light was off and the gauge read normal. This was with full load ie, a/c,headlights etc...

Next day it was fine no issues. Been parked till today. Drove it 10 miles, light back on and gauge quickly going down down down, had to limp it back. DEAD battery now and im out another alternator?

Any ideas? All the wiring looks good as do the connections going to the alternator

I'm going to pull it tomorrow and take it in to a starter/alternator repair place to see what they can tell as to what is burning it up....

Any ideas would be much appreciated!!!
 

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Posted by JohnB (Member # 969) on :
 
Sounds like you're getting field current within the alternator, even with it being off and key off. This will burn up the diodes within the alternator almost immediately. Two ways to check your problem:
With everything connected, key off...check to see if you have a magnetic field around the alternator. You should have one with key on.
Second thing I would check is the small alternator harness. Its the small connector next to the engine bay fuse box. I would check it for a short, via a multimeter. Pin out each lead. Ford still sells it, it's around $40. Here's a pic:

 

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Posted by 89foxstang (Member # 5908) on :
 
its a long shot but have you had your battery tested? if its constantly low causing the alt to be working harder that could possibly make it go out sooner.. the above sounds like a more likely solution although how do you check for a magnetic field?
 

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Posted by JohnB (Member # 969) on :
 
A bad battery is defnitely a possibility...I'd hope Matt checked that already.

quote:

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Originally posted by 89foxstang:
How do you check for a magnetic field?

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Place a small flexible piece of metal near the alternator with it off...if it attracts, there you go.
 

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Posted by 89foxstang (Member # 5908) on :
 
Yea well sometimes the simple stuff is the stuff that gets overlooked i know im guilty of it sometimes thanks for the info!
 

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Posted by HaulinAss Motorsports (Member # 541) on :
 
Thanx John ill check that out. And yes its a completly different battery.
 

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