My left brake tail light doesnt work. It works only when my lights are off, but when my lights are on and I hit the brakes... it doesnt function. Ive taled to the dealership about this and they said I need a new tail light!!! Ive noticed other Jeeps on the road with the same issue. Any advice?

Your right brake light is not the same bulb as your rear running light that comes on with the headlights. Different bulbs. Your right brake light is simply burnt out or has worked its way out of the connection. Take it to Advance Auto Parts. They may even change it for you. Not a big problem.

Look for a poor ground on the LH light assembly. You'll need to remove the assembly to do this.

You need a repair shop

have you checked all fuses?

didnt specify vehicle -- generic answer -- recheck bulb new doesnt mean free from defect also check the socket --the light that lights up can be the tail lights some vehicles have one bulb but has 2 filiments [brake tail ]

Have you checked the socket to see if 12 volts is reaching the socket for brake light citcuit? Probe the wires with a 12 volt test light probe (avail from any parts store for about $6)

Both of your rear lights must be out if it was a brake light switch or fuse you would get no lights at all. It also may be a bad turn signal switch causing the right and left lights to not get power.

check the fuses. also check for a bad ground.

you prob got a trailer plug prob bad wires if not tail lights run through turn signal switch tell fix ya bout me ok

Did the new lens come with new sockets? If not damage may have occured there that you cant see. only other possibilty is wiring damage in the rear that may be hard to see. The condition you describe is simple "backfeeding" if you look hard enough youll either find bad sockets or damaged wires close to the lens that took the hit. Hope this helped. Thanks