how to replace left side (drivers side) brake lamp. running lites are ok.2004 Cadillac CTS
this might help...
From the inside of the trunk you will see plastic cargo net retainers, turn to the left to loosen and pull upward slightly, then you remove the plastic that covers the trunk latch by lifting straight up. Now you remove a couple more located in the carpet which are the same as the plastic cover ones, move the carpet out of the way and you will find 2 nuts on studs facing foward behind the carpet remove these nuts and be carefull not to drop them, they are difficult to retrive but a magnet on a stick will work if you happen too. The light assembly will pull rearward from the outside at this point, push and turn the plastic lamp holder and replace the bulb. It will help if you remove the cover for the spare tire and also remove the cargo net retainer that is on the upper side of the side on which you are replacing the bulb that is about one foot forward of the rear. That will help pull away the cardboard type carpet from the side. You will need a 10 MM wrench to unscrew the nuts on the stud that hold the light assembly in place. The brake light bulb is the one at the top of the rack of three bulbs.
To achieve the best effect of warning, many spare brake lights 3rd adopts LED rather than a filament bulb or a central group of incandescent lamps.___________Hanglampen