Alright noticed this last night while driving up to NH for a friends Christmas Party.
I had my windows down a little bit and decided to roll them up after the car's heat evened itself out enough for me. As I was all alone on the highway I noticed that my lights dimmed dramaticly. At first I thought my eyes where messing with me so I rolled them down again and noticed the lights dimmed once more and again as I rolled them back up. I waited till I got to my friends house to try a few more things like trying the interior lights and same thing happened the lights dimmed. After this I left the interior lights and tried my windows again, both the interior lights and outside lights dimmed.

So question is, is my alternator going or do I have a bad ground wire? If a bad ground wire where do I find it and make sure its tight against the body of the car (never had to check before obviously). If alternator 2 things, what's the voltage supposed to be at and is this covered under warrenty.

Thanks guys

 

It could be as simple as a corroded battery terminal. Then again, it may be the alternator. I can't remember if you have an amplifier pushing a lot of wattage, but the power windows use a lot of current and if your stereo was thumping, you may see some dimming.

 

Lol -- I used to have fun with this one. When I was a kid I noticed I could dim the headlights on my Dad's car from the back seat with the power-window buttons, and if you pushed "up" while they were already up, the motor drew even more current. And, if you engaged both windows -- this had a dramatic effect. I would do this intermittently and for a long time my father would bitch about the "weird electrical problem". Until he caught me laughing.

 

do you have undersized pulleys installed? if so, they will make the lights dim when you use the windows and low rpms.

 

^Nah no "Custom" pully's on my car as of yet. I think its as Nubo said, the window buttons are drawing extra current when the windows are all the way up. Kinda stupid really you'd think after how many years we've had motorized window's they'd of created some kinda I dunno censor that would detect if the window was all the way up and if you still pressed up nothing would happen. lol.. well I'm glad its common (to a point).