1996 GT Charging Issue - Ford Mustang Forum
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post #1 of 5 (permalink) Old 10-16-2011 Thread Starter
dethanb's Avatar
Joined: Sep 2011
Location: Oregon
Posts: 29
1996 GT Charging Issue

G'Day to you all,

I have a dilemma with the charging system in my Mustang. During normal daytime driving, my battery seems to stay charged (minimal load). I've monitored my volt meter and it stays (relatively) normal. At night I've noticed the volt meter slowly drops down to 8-10 volts or so. During this time I see the lights dimming, and the car runs a bit rough. It sometimes bounces back up to normal charging area, and then slowly progresses back down to 8-10 volts. Tonight this occurred and the car finally died, dipping below the 8 volt mark. Fortunately, it died near Wal-Mart and I was able to get another batter to get me home. With that being said, all the way home the volt meter stayed in the normal charging range all the way home, 40 miles.

Things I've done to fix the issue... I've purchased a new battery a couple of weeks ago (the same one that died tonight). I've replaced the negative cable as it was completely corroded from the battery terminal back from the previous battery. I've removed the alternator and took it to two different auto stores and had it tested and it came back as being "Good" at both (Autozone and O'Rileys). I assumed it was the alternator as I couldn't think of anything else that it could be???

Does anyone have any other ideas as to what might be causing this issue with my GT? I've done some searches and don't really find anything relating to this. My assumption is the Alternator/Regulator is bad, but I had it tested at two different parts stores? I did drive home tonight in 4th gear to keep the revs a bit higher (2500 compared to 1500). Again, the volt range stayed normal during the trip home, and prior to I was in 5th at 1500 RPM. Could it be the Alternator just isn't putting out enough power at 1500 RPM?

Any input would be great as I don't know where to go from here?

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post #2 of 5 (permalink) Old 10-16-2011
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You wouldn't be the first guy who had an alternator test 'good' when it wasn't. Before doing what I'm about to suggest, check the return policy just in case I'm wrong so you don't go spend $1xx that you can't get back and still haven't fixed the problem (and also don't return your existing alt. for the core return until you confirm the problem is fixed), but I would go get another alternator. Drive it for a few days or whatever and see if it's not as good as new again.

2001 GT Convertible
/1967 Coupe
All the usual bolt-on's /200 I6, C4

And a few Explorers too... 2008 4.0 XLT 4x2, 1996 XLT 5.0 4x2, 2003 Sport Trac XLT 4.0 4x4
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post #3 of 5 (permalink) Old 10-16-2011 Thread Starter
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Joined: Sep 2011
Location: Oregon
Posts: 29
That's what I was thinking... I'm guessing it's the voltage regulator, but they are one in the same these days. I just ordered one from AutoZone, so it should be in tomorrow. My guess is it just isn't working correctly at the lower RPM. I don't know what RPM they spin it up to when testing, but apparently greater than 1500?
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post #4 of 5 (permalink) Old 10-17-2011 Thread Starter
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Joined: Sep 2011
Location: Oregon
Posts: 29
Well, for an update to anyone who reads this thread, I replaced the alternator today and took it on a 100 mile trip. Not a single problem with the charging system. I had the headlights, fog lights, heater on high, rear window defroster, and stereo all on with periodic rolling up and down of the windows during the whole trip. It ranged between "R" and "M" on the volt gauge and never sputtered once.

So, if "TWO" different stores tell you the Alternator is "GOOD" but you've experienced the same problems as I did, (I knew it was the alternator hence the second test), it might behoove you to trust your gut, and not the tech running the machine!?
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post #5 of 5 (permalink) Old 10-19-2011 Thread Starter
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Joined: Sep 2011
Location: Oregon
Posts: 29
Okay, next issue...

I've installed the Alternator and all seemed to be working just fine. Today I've noticed the "battery" dummy light was coming on (periodically). It never stayed on for any amount of time, just flickered, or maybe stayed on for a few seconds then went off.

Is this an issue with the Alternator, or did I fry the battery with the bad alternator completely draining the entire battery several times?! Everything seems to be working just fine with the exception of seeing the battery light flicker now...
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