2006 monte carlo lt tail lights not working - 1995 Mitsubishi Galant

Yes sir, MOST are.Except tail light bezels.

did you check all your fuses

you could have blown some fuse while installing the stereo. check the fuses, wires that may have been cut or disconnected.

the bulbs have 2 filiments,one for brake one for tail light. check bulbs if they good your swich is bad

check blubs if the center light works should be working side brake lights

Sounds like a loose connection -38 is probably the open circuit position. Not sure where the sensor would be though.

The 3rd brake light working does reveal that the fuse is good, and the brake switch is good. Check the bulbs, sockets, and the wiring between the brake lights

It could be wiring, a bad ground, a defective plug to the tail-light, the tail-light itself, a loose fuse, or a dirty or faulty connection at the hazard switch. If it is the hazard switch you can try to actuate it (on and off) 6 to 12 times. This may help clean off the contacts and let the brake lights, return to normal.

There is an integrated phone feature offered by OnStar if you want to pay the outrageous cost. It works through your speakers