96' Grand Prix problems

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fcfdf10

Hello I have a 96 Grand Prix we have had since 97, never had a lick of trouble with it until I replaced the alternator on it about 2-3 years ago, and since then have had the alternator replaced and or rebuilt 5 times (kinda gets old taking it out and putting it back it)
Today I had to take it out again (just did it a week ago) and noticed a wire plug not plugged into anything, on the clip it says "PED 10" for what that is worth. The plug looks as if it hasn't been plugged into anything for a while due to the dirt and grease build up in it, it has 2 wires on it, it is near the fire wall and obviouslly next to the alternator, don't see an obvious place to plug it in to.

Could it be a test port?

Any ideas on why I have bad luck with the alternators?

The alternator rebuild shop is very reputable, i have had them rebuild for me on the other 2 vehicles I own, and this time will be covered under warranty, but gets old getting the alternator out of the Grand Prix engine, if any body has done it, they know what I am tazlking about.

Thanks for the help in advance!
 

87 GP

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The plug might be a test plug for the fuel pump? Not really sure but some GMs have this. Maybe you are over tightening the belt? If not check the battery with a tester for batteries. It will do a load test and can also diagnose dead cells. Be sure the connections at the battery are both clean and tight. If the alternator is searching to complete the circuit it will wear out faster. The only other thing that comes to mind is I think the volts are regulated by the on board computer in your car. Hook up a scan tool and see what the values are for the charging system and if any codes are stored or pending. You didn't mention what the problem is but I'm assuming your battery goes dead? Or is it overcharging?
 
F

fcfdf10

the battery is brand new, as of Sunday,, it is running the battery down all the way, all connections are tight, had the alternator rebuilder look at it, and he was scratchin' his head just like I was/am.
thanks
 

87 GP

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So the alternator definately isn't charging? How many volts is it showing when at idle and then about 2500 rpm? Like I said above, I think your computer regulates the voltage. So if the alternator checks out OK the problem could be the wiring to the computer or a pinched wire or a bad computer. I doubt it's the computer itself. Probably just a bad connection or shorted wire.
When you return the alternator, does the rebuilder test the old one? What does he find? Anything burned or shorted?
Another idea might be to bite the bullet and bring it to a GM dealer. Let them install it and it will have a lifetime gaurantee.
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F

fcfdf10

yes the rebuilder tested it while I was there, and it was bad, they rebuilt the old one, it is a genuine GM one, that was put on some time ago, but wife can't find the receipt to get the warranty (surprise surprise) any way picked it up today, and they said a (something) was broken and fixed it no charge (wondering if it was something they forgot to fix the first time?!) anyway is fixed and back on, we will see if it quits in a week or so again.
 
F

fcfdf10

ok, now I have another problem, I had the alternator rebuilt again, and today, go to it and nothing, like a dead battery, hook up the battery charger, nothing,, put my littl ejump start to it and it cranks kind of, finnaly starts, checked the battery and alternator, both show 14 volts +- now what?? maybe a starter?
 

TropicDave

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Has to be a bad connection or short, like 87GP says. There's really no other way to lose a charge like that (presuming you had everything off, that is, and I figure you did). Check your wiring harnesses for a short, see if anything's grounding out against the block, etc. That's where I'd search.
 

427HEMIPONTIAC

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I had a bad rectifier bridge (one diode shorted) and it was draining the batt. Also got some strange things in the car happening too. (1980 Turbo T/A).

I found it when the engine was cold, and the alternator was warm once I connected it up back up.
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U

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definately sounds like a starter issue......sounds weird, but if the starter is acting up it will use way more juice than normal and will kill the battery, hence damaging the alternator....
have the starter tested.....I'm 99% sure it's the issue...I have a 96 coupe and it did the same thing..it was the starter.
 

TropicDave

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If that doesn't solve it I'll take a look in my manuals for my '92...the electronics should be similar since there wasn't a great change between those years (I have a factory service manual set for the 92 GP, three volumes, fairly detailed, but of course I don't have the special tools they call for).
 
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