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Discussion Starter #1
Periodically, I will be driving and the battery light will blink several times followed by the musical tones of the check alternator light. This continues several cycles, and the A/C stops cooling, and the ABS light comes on. It also appears that at night, the lights dim.

If I turn the car off, re-start, everything is normal. This has happened about five times. I have been to the dealer, had the battery replaced and the alternator checked. The alternator was fine.

I see in other threads that other strange warnings and gage readings have occured (temp, speedo, tach) with no actual problems being detected.

Has anyone else had this battery-alternator-ABS-A/C phenomenon? Any advice on correction?

I have a 2004 GTO, automatic, Comp Cam, longtube headers, FAST intake
and a Procharger.
 

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I would take it somewhere and have an official charging system test done.

If you have a multimeter, you can check for AC voltage bleed through. Another thing you can do is test the "DC Sense" wire for voltage versus the battery. Essentially a voltage drop test. Our alternators ARE NOT controlled by the BCM. I used the GTO for a starting/charging system circuit diagram presentation in my Autos class, so I studied it's function pretty closely.
 

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Could be a loose wire or ground. First step in trouble shooting is to move and jiggle wires. Everything is great, hit a bump or the engine torques and move the wire and now it doesnt charge. Move wires around and see what happens. Anything from the starter wiring to the alternator wiring could be bad. Change the alternator or aquire a good used one and see if it still does it.-----Danfigg
 

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Discussion Starter #4
Finally got it to the GMC dealer while the warnings were flashing. They determined it was a bad alternator. Replaced it and all seems well now.

When they checked the alternator w/o any of the warning messages, the alternator checked out fine.
 
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