I've had this problem since I picked the GXP up. I'm now at 5000 miles. I've been hoping it would get worse or better before I had to do anything. Maybe someone else has had this experience...

The volt gage wiggles constantly; 3 to 4 times per second. It'* a little tough to judge the scale, but the wiggle is about 1 volt. The average voltage is about 14.5 volts; it does all the wiggling at just above the 14volt mid point. I know that the gages are not known for their accuracy, but are mostly used for relative readings. But I have never seen one move that much.

The second related issue is that occasionally the voltage will momentarily dip down about 1-1.5 volts below 14. At night, the headlights will dim quite a bit. There doesn't appear to be any related action; day/night, a/c on/off, 0-75mph, etc

It'* definitely going to get a trip to the dealer, but I'd sure like to have a clue as to what I'm dealing with. Probably a voltage regular problem.

Z there'* another member with that problem in the threads somewhere down below and I dont think anything was resolved of it. Have ya checked the ground strap under the seat . I think theres a tsb about some bad And the floor pan corroding

Here is the floor pan TSB
Component Description:
6. STRUCTURE:BODY Bulletin Number: 050861002
Bulletin Date: MAR 2005

Vehicle: 2005 Pontiac Bonneville
Summary:
FLOOR PAN CORROSION PERFORATION IN BATTERY COMPARTMENT. ( NHTSA ITEM NUMBER - 10013452 )

I cant find the ground one just know (so much stuff i keep collecting) and not filing it well. I think checking the ground strap would be a good place to start at Just about all your mentioning could happen if it'* loose

I would get that checked asap. Even with HID my lights dont dim and I have never see the volt gauge move.

I havent had the voltmeter wiggle at all but I too have the same issues with the volts dipping regularly. I took the car to the dealership and they ran some tests and they said everything was okay. They gave me a GM "Info Sheet". (Document ID #1540541)

See http://www.berettaspeed.com/canada/*...ument%20ID.doc

The last time I had the car in there were some codes saved. There was a code regarding On-Star and another regarding the Interior Dimmer Switch. They indicated that only one code for each was saved so it was a one time occurence. It was explained that I dont make enough lengthy trips so the battery is not charging. Funny.......I have had the same driving habits for years and this is the first car where this happens. (I call bullsh*t on the battery not being charged enough).

I had a meeting with the regional service manager regarding this issue and many others and he said it is quite normal for the voltmeter to drop and the headlights to dim. However, he couldnt really explain the codes that were found.

I will be in contact with him again soon again, we will see what the results are.

I'll take a look. It could be a bad connection, but I think it'* too consistent for that. I haven't been under the seat yet. I understand that it just flips forward?

My problem occurs at all rpms and I don't have a low battery problem. So far, it'* just annoying. But if they hand me an "info sheet" that reads like its written for a 2nd grader, I'll get really pissed.

I did come across something about an electric Air pump? I have one on the Camaro, but no voltage/light drops on it.

Mine doesnt do it while idling either. They just handed me the sheet to try to get me out of their hair. And I am not convinced that there is a low battery problem either. It sounds like we have the exact same problem with the voltage drop. Except my gauge doesnt wiggle.............yet.

LOL Z, ya it'* reads rather like something handed to a second grader but did have some good info in it . I was suprised at the amp load with all the bells and whistles going; the alternator is going full blast and I'm gonna have to get a much larger one before I get my dual air cpmpressor setup and audio amps for the new rear speakers and sub woofer fully installed (And Will Wren told me as much ) The rear seat has to be pulled up about two to three inchs from the front first to release the catchs(though their not half as ackward as the old style ones) then pull from the back and the whole seat flips out, The ground strap lug thats screws into the body is about a foot from the battery and though the lug looks large enough for the current, most of the area of the lug is on a painted surface. I felt that might cause the pan erosion... I took off ground lug and sanded that area under the lug and smeared some Ox Gaurd on the bare metal to prevent galvanic corrosion. if you dont have some on hand it can had at Lowes for a buck something in the aisle with wire connectors and such. I am really surprised at the small wiring and lug sizes for positive polarity connections through out the whole system cosidering the length of the positive wire to get back to engine bay. There is a large fuse/relay box there to get a good gander at for reference also

It has been a few months, hasn't it. I'm now AT 14,000 MILES.
I had to take my GXP in for some repair work related to my own stupidity, and had them look at the volt gage. They replaced the cluster, and it still does the WIGGLE JIGGLE. At least they haven't made any excuses.... yet.