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Discussion Starter #1
Hello...
My wife's '06 G6 GTP isn't charging. I took the alternator to AZ this week, and it tested good. The battery is only about 4 months old. The problem basically started right after we had a mechanic replace the oil pressure sending unit, which is located directly behind the starter. I can't say for sure, I wasn't there, but I'm wondering if he could have shorted the starter while working in that area, pretty sure he removed it to get to the sending unit..... Say, if he didn't disconnect the battery before climbing under the car. I was on the verge of changing the alternator then, it was reading low at the battery, but it started charging ok, 13.4volts..ish.
Now the problem is back....
The starter itself is working great, no problems with the starter at all, at least while the battery is up. I haven't actually checked the wire of the back of the alternator for continuity, but I DID check it for voltage to ground( while disconnected), and it was the same voltage as the battery, so probably safe to assume there's continuity. Later, after reconnecting it to the alternator, we started the car, and I measured again, running. The battery was low, but it still started the car, still wasn't charging, but this time battery to ground read about 11 volts, way low, but at the alternator it read a full 3 volts lower, while running. By this time of course the car was running rough, so we turned it off.
I'm bumfuzzled, never ran into this before. I thought for sure the alternator wire would check bad, but I'm afraid I don't understand all I know.
Any ideas?
Many thanks!
 

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I was puzzled as to why you would take your alternator to Arizona, then I realized you meant Auto Zone. Your alternator may be having intermittent problems or maybe Auto Zone's test was bogus. I don't have much faith in tests run by counter clerks. If the alternator is showing a low output, replace it. Rebuilt alternators are not all that expensive.
 

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Discussion Starter #3
Ummm...I don't either, but I went back with him and watched, a lot more automated than it used to be. Far as I could tell, HE did it right, but the test just gives green lights, as to the diode test, regulator,etc...
Is it possible for an alternator to be failing but still working? I've only encountered not charging at all in the past.
 

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Discussion Starter #4
Plus, it's not as easy to get parts , like brushes, regulator, diodes, as it was just a few years ago.
 

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A cheap multimeter would allow you to check voltages at the alternator and battery. Also you could test for continuity. If the positive side of the circuit is good you could also check the grounds. You need a complete circuit for the alternator to charge the battery. If you have jump leads and are careful you could connect the engine block to the battery negative to see if that improves things (bad engine ground). You could also try the positive to the alternator positive. Just a thought, but please be careful, connect it wrong and sparks will fly...
 
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