I need a sterio wireing diagram for my 02 buic centry i dont even know the hot and the ground

The wire's don't go to the firewall . Both wire's go to the blower motor resistor assembly . Located on the heater / A/C case near the blower motor . Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on HVAC , then under subsystem click HVAC controls . Click the search button then click the second blue link . Do you know what a wiring diagram is ?
Electric Testing Techniques You Need to Know

Do a Google search using the correct spelling: STEREO.
Many wiring diagrams online... you just need to use the correct spelling! :)

If you are putting in a after market sterio,you need to go to autozone or walmart and get a sterio plug that plugs into your factory plug and the wiring diagram will be with your new plug that you bought,real easy!!

all recalls for vehicles older than ten years are removed. you can call a buic dealership and give them you're vin number but most likely will not have any recalls for that all i ran into this problem my 1992 buic rear leaf spring.

Sounds like the previous owner patched a hot wire to the rear lights instead of fixing the problem.
Someone will need to get the factory wiring diagrams and start backtracking from the lights to the dash to find out what is wrong. You may need a shop manual to get the diagrams you will need. Most repair books do not go into wiring that deep for the DIY.

dont know about a or b but here is diagram by color code

Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

I'm not sure what you mean by headlight covers. If you mean the lens that is supposed to be in front of the bulb, you need the whole headlight assembly. Check with your local junkyard. Those would go for about $20-$40 each around here(SE PA).

its possible if Ur very careful u need the power wire/ ground and all the speaker wires u can identify these using a multi meter to determain which is the power wire and ground the speaker wires shoul be similair in color like solid brown then a brown with a stripe on it them solid green then a stripped green etc.

I'm not sure what year you have but this color code works for 87-93 mustangs.

Radio Connector:

Light Green / Yellow - Hot at all times (Fuse 8)
Yellow / Black - Hot in ACC or Run (Fuse 11)
Light Brown / Red - Goes to instrument panel dimming rheostat (Fuse 4)
Red - Ground
White / Purple - Hot in ACC or Run (Fuse 11)

Speaker Connector:

White / Light Green - (+) Right Instrument Panel & Door Speaker
Dark Green / Orange - (-) Right Instrument Panel & Door Speaker
Brown / Pink - (+) Right Rear Speaker
Pink / Light Brown - (-) Right Rear Speaker
Pink / Light Green - (+) Left Rear Speaker
Tan / Yellow - (-) Left Rear Speaker
Light Brown / White - (+) Left Instrument Panel & Door Speaker
Orange / Light Green - (-) Left Instrument Panel & Door Speaker
Hope this helps.

wonder why it doesn't blow a fuse? follow the wires that get hot all the way back to power and ground yes wiring diagram would help you say clutch doesn't kick on or off, it pretty much has to be engaged or disengaged, prolly engaged if wires getting hot. if a/c blows cold, it's engaged.try unplugging compressor or removing belt or both and see if vehicle operates ok without it, then you know where to start