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lets start by saying I have some knowledge when it comes to mechanics, but at this moment I am at a loss, last night I was driving home from work about 10mi and my volt gage was reading about 8 volts, way too low. but I was running my stereo, headlights, and the vehicle without the gage dropping any, I made it home and let the car sit over night, started with no hiccups other than the gage reading low, drove to my bank and the TC light & ABS light came on and said service stability system, i drove to the local orileys and had the charging and starting sys checked, the battery read needing a charge but ok with vehicle off, then started the car no problem again and the machine said the starter failed, the alternator and the voltage regulator were giving bad readings, I have been looking to see if I could find easy ways to replace my alternator if that is even my problem, any help would be greatly appreciated

My 2005 GXP experienced these same symptoms a few weeks ago with the additional indication on the DIC of "entering battery saver mode". It was diagnosed at a GM dealer as a bad alternator. The dealer recommended a Delco alternator, which they did not have in stock, at an ungodly price. The local NAPA had a rebuilt unit (145 amp) with a three year warranty in stock for $149 plus core charge. I provided the NAPA alternator and had the dealer install it since the vehicle was already there. I'm not sure I would want to attempt an alternator change without the use of a lift since it is not very accessible from the top. Good luck if you decide to do it yourself.

Actually, it really isn't too difficult to replace the alternator. You may or may not have to remove the cooling fans to allow room. But otherwise, it's removal of belt, disconnect 2 or 3 electrical connectors attached to the harness, then 3 bolts.

To me, it sounds like the voltage regulator. But another thought I have is that it could be "power moding" or more or less the electrical systems' way of regulating electrical load. Do you notice it trying to raise the RPM? Do you notice it trying to reduce electrical load (I.E. shutting off A/C, heated seats, rear defreoster, or blower motor)? If it is, this is another issue.