Check and make sure you have 12volts and a ground to the lights sockets. It takes both to make the bulbs burn. Check for corrosion and broken wires.
Check bulbs
check your bulbs some bulbs have two filament on them one may be out and the other working.
check fuses then check all the bulbs, then check the turn signal switch the brake lights work through it
my daughters 1991 miusbishi montero has no break lights , turn signals or hasard lights . All tail lights and front markers are working. All fuses are cking good and all bulbs are good..Is my blinker switch bad ? capri
The light switch.
There are two (2) lights directly above the license plate. Each light has two (2) screws. Remove these screws and the covers. Lights pop out with little effort. Replace bad bulbs with size 194 lights. These are approx $2 at walmart or an auto parts store. Once bulbs are replaced, reattach covers with the screws and you should be good to go.
the wirehas been eaten by rates of mouse
Check the cable, it gets broken especially in the places where you can see it or at its movable parts.
You need to remove the liner on the trunk lid. That will give you access to the license plate lights housing. Remove the sockets by twisting 1/4 turn and replace bulbs. Size for bulbs are 2825
Change brake light bulbs Just remove the rear license plate. You can change the backup lights and brake light easily.
Check both bulbs, they run off of the same fuse as the tail lights,
on some cars the tail lights and brake lights are totally different bulbs gain access to the bulbs and have someone push the brakes so that you can determine which bulbs are the brake lights and replace the tail lights