2004 Grand Am headlights dim when using power windows and brakes.

I just bought a 2004 Grand AM V6 GT. Of course I test drove it in the daytime so it wasnt noticed. When I roll down the power windows my headlights dim. And also, when I hit my brakes. I called the dealership which, of course isnt close to my house. They stated that it may just be normal. I dont think so. I have NEVER seen this before on any car. I have been told by my boyfriend that he knew someone who had this problem and they came out of the store with their car on fire, nice. I basically want some things to come back with if they try to tell me it is normal. It is still under warranty so I am going to make them fix it before its up. PLEASE help! Also, if anyone may know of any common problems these cars have I would really appreciate knowing what they are. Oh, and It also has a moonroof. Leaking problems?
Thanks so much,
Stella
Great site!

How bad do they dim??

My 2001 Grand Am GT will have the headlights dim just a little if the window is all the way up and you are trying to roll it up, same goes for when it is down.
While sitting at idle in park, I will get a quick dim of the lights when I hit the brake to put it in gear.

I consider both completely normal.

There are a couple of things to check if this happens. First, make sure that battery terminals are clean and the grounds are good. Check the battery terminal as well as where the ground cable connects to the block. Check the alternator output as it may be too low, you should get 14 volts when the car is running and finally check to make sure the battery is fully charged. A low battery condition will cause this problem.

Yes, it does happen when I hold the window button down after it is down, and or up. It doesnt dim much. Not to noticable if you werent looking for it. I think I will just have them check it out when I get routine maintenance done.
Thanks so much for your replies.
Stella
Ohhhh, I made a mistake it is a 2003 not 2004.

If the problem continues, or gets worse you may want to check into the battery/alt. system make sure that you have enough output from the altenator.

Or see if you are draining power by having other accessories on at the same time, like your radio, heater/ac, rear defog, etc. They will put a strain on system, that alternator/battery can't compensate for at the time the windows are also being used.

And, generally, it is fairly normal for dimming a bit, if lots of stuff is turned on at the time. But just a bit, not a lot .

I have a similar issue, 04 Se tapping on the brake to kill the curise makes the head lights dim, also asked the dealer when I have it in one of the 5 time in the 6 mo. that I have had the car ahd they said it was normal also. I did not press the issue since I had larger issues at the time.