2005 Pontiac Grand Prix front left turn signal went out, I replaced the bulb and the light comes on but the turn signal still doesn't work. If I have the lights sent on automatic the right parking

SOURCE: 2004 Pontiac Grand Prix GTP front pass turn signal doesn't work

you would need to buy a blinker relay

SOURCE: Sent an email earlier before I finished the

has to be somwhere in the wiring for the tail lamp brk light. if the high mount works the switch is good. did you put the correct bulbs in? they may share a common ground independant of the other lights.

SOURCE: I am trying to replace

If you are looking at the light on top and on bottom you will see a little U shape in the light. it his held in by 2 screws. if you use a start screwdriver youll pull it right out. its an easy fix.

SOURCE: I have a 96 Pontiac Grand Prix..., & The Left

More than likely it's not all the bulbs that are burnt out. Your head lights work like a relay if one bulb is bad then none of them work. Try looking for the bad bulb (this will require you to pull the head light assembly a part to look at the bulbs) what you are looking for is blackening around the clear part of the bulb, also if you pull the bulb out of the socket and give it a bit of a shake does it make a rattling sound? If so then it's bad.
In regards to your left turn signal have you replaced the bulbs or check to see if they are burnt out as well? The also operate as a relay and will not work if one is burnt out.
You may be right about it being a switch. If you have the time, take the door panel off which can sometimes be a pain, **** worth it. Check to make sure the wires are still connected properly. If they are then i would look in and around the window tract to see if there is anything that could be impeding the window from going down. Other wise it could be a bad button system and just the drivers side button is shot. You may have to replace that. Hope this helps. Good luck.