I have a 1987 Trans Am GTA w/o steering wheel controls. Couple days ago, I lucked out at a j/y and found one of the late-80s/early-90s Pontiac CD Players that actually works. The radio has the 21-pin style connector out back, while my car had the 3 big connectors from the factory. I cut those off and spliced the 21 pin in its place. The radio works fine, but I'm having a couple issues. -First, when you turn the key to ACC and turn the radio ON, the lights in the car come on kinda dim. I hear what sounds like a relay clicking behind the dash on the pass. side. I smelled something that smelled like electronics burning, so I unplugged the radio. Thankfully, nothing was damaged. -Second, if I fool around with the dimmer switch, I get a little static in the left front speaker. Anyone have any ideas what could be causing this? I matched up the coloring on the wires pretty good, but I'm looking over everything. I don't have a wiring diagram for the factory wiring, but I do have a diagram for the 21 pin out of my 91 Camaro manual. I figured they must be the same as the Firebird. I did hook up a pink wire on the connector to a pink wire in the car, but the 91 diagram says it isn't used. I unplugged it but it didn't help. Thanks for any advice you can give me! Kevin

i cant think of a rhyme nor reason for either of those two things to happen but your issue has been boggling me all day, i would guess something along the lines of you hooked a speaker wire up to the dimmer control but i don't know, I ran it by a co-worker (i work as an installer) and he came to the same conclusion. but thats neither here nor there, ill do my best to help you.

all of the colors are the same between all third gen birds and probably camaros for that matter so your method of matching wires up probably worked but i copied and pasted wiring lists for you anyways.

if your car rolled up to my shop after double checking all of your wires and seeing that they were properly connected i would first disconnect the dimmer wire (brown) from the radio as there may be an issue with the radios internal illumination. if that doesnt fix it try running a new wires to the left front speaker because the wiring is 21 years old and with age wiring can break inside the insulation or the insulation can wear off and make it ground out. plus the radio is a whole 2 feet from the front speaker its not hard to run that wire, let me know if that solves your problem.

this is your car
1982-87 Pontiac Firebird Stereo Wiring Constant 12V+Orange Switched 12V+ Yellow Ground Black Illumination Gray Dimmer Brown Antenna Trigger Pink Antenna Right Front Front Speakers 4" x 6" Dash Left Front (+) Tan Left Front (-) Gray Right Front (+) Light Green Right Front (-) Dark Green Rear Speakers 6" x 9" Side Panels Left Rear (+) Brown Left Rear (-) Yellow Right Rear (+) Dark Blue Right Rear (-) Light Blue one of the following two is the radio
1988-89 Pontiac Firebird Stereo Wiring Constant 12V+Orange Switched 12V+ Yellow Ground Black Illumination Gray Dimmer Brown Antenna Trigger Pink Antenna Right Front Front Speakers 4" x 6" Dash Left Front (+) Tan Left Front (-) Gray Right Front (+) Light Green Right Front (-) Dark Green Rear Speakers 6" x 9" Side Panels Left Rear (+) Brown Left Rear (-) Yellow Right Rear (+) Dark Blue Right Rear (-) Light Blue
1990-92 Pontiac Firebird Stereo Wiring Constant 12V+Orange Switched 12V+ Yellow Ground Black Illumination Gray Dimmer Brown Antenna Trigger Pink Antenna Right Front Front Speakers 4" x 6" Dash Left Front (+) Tan Left Front (-) Gray Right Front (+) Light Green Right Front (-) Dark Green Rear Speakers 6" x 9" Side Panels Left Rear (+) Brown Left Rear (-) Yellow Right Rear (+) Dark Blue Right Rear (-) Light Blue all of this is courtesy of the12volt.com

Thanks for the advice...that's exactly what I did. GM in all its infinite wisdom made one of the front speaker wires and the dimmer wire the same shade of grey, so I got confused . But all is well now, thanks!