04 Impala ... Bright Headlamps Stay On
 

Recently require my first Chevy ... 04 Impala (used obviously)

When I bought the car it was during the day and of course I didn't even check out the headlamps because I'm an idiot.

That night when the headlights turned on automatically only the brights were on and I can't get them to turn off.

Even if I pull the dimmer switch out during the daytime the brights are still on.

Do I need a new dimmer switch or a new multi function switch?

Or am I even close. I've check all the fuses and they're fine.

Sometime's there isn't enough information, and then there are times when there is too much.

Let's start from the beginning with a course on how the lights are supposed to work:

Not a cloud in the sky, sun beating down, you get in the car and start it up. Being bright out you don't turn the lights on - DRL's come on automatically (Hi-beams but dimmed).
You drive for a few hours and now it is pitch black but you still haven't touched the light switch - DRL's switch off and your Low-beams come on automatically thanks to the sensor on top of the dash.

On the other hand, at any time of the day(!), if you pull the light switch to the first position (parking lights) than all your headlights turn off and you should have the corner lights and dash lights on. Pull it to the second position (ON) and your Low-beams should come on, then you can switch to Hi-beams by pulling the multi-function switch towards you.

As for the "dimmer", it only affects dash lights.

So to be specific, pulling the switch doesn't turn your lights on at any time of the day? What happens if you don't put the key in but turn the lights on? Ever since GM moved the brights switch from the floor to the stalk it's been crap...do you have the brights icon illuminated on the cluster? And pulling the stalk doesn't turn them off?