Without doing a "hands on" troubleshooting of your vehicle, no one can tell you what specific defect is causing your problem. Therefore this answer will of necessity be generic in nature.
Usually this type of problem is caused by what is called an "open circuit" condition.
Open circuits can be caused by several things, a few of which I can recall now:
It is very frustrating to replace an expensive and difficult to install component only to find out later that the problem was caused by something else, and there was nothing wrong with the replaced component. So, do a thorough investigation of all the connectors, connections, splices [if any], and all ---components of the nonfunctional light circuits BEFORE replacing anything.
I would first check to confirm that electrical power is getting TO the main light switch, and then is coming OUT OF it. IF power is present at both points, then fully inspect and check all of the wiring harnesses and connections [plugs, splices, etc.] for the affected circuits.
in dash lights
Is it the taillights or the brake lights? If taillights it may be a wiring problem, If brake lights check the switch on the brake pedal
The bulbs should be checked on a 1993 Dodge Dakota if the taillights are not working. The plugs on the trailer package should also be checked to make sure that they are working.
Possible ground issue at the taillights.
you need to repair the lights and they will both work and your taillights will work properly
Do parking and dash lights work? If not, may be fuse most vehicles it is the same circuit
faulty brake switch
If the turn signal is working it's either the brake light switch or the turn signal switch.
It should say TAIL for taillights or maybe brake lights.
Check your fuses! -I once got a ticket for 'no taillights' when my dashlights were fine -it was the fuse.
Sure: you don't have a complete electrical circuit to working bulbs. Are the bulbs good? Fuse? Have you checked the ground wire at the taillights? Often on older vehicles the ground connection becomes rusted and the lights will stop working. Have you verified that voltage is present in the tail light wire? Sometimes a faulty connection somewhere between the switch and the tail lights will cause the lights to fail. Have you verified that the headlight switch is functioning properly? While Brake lights are controlled by the brake light switch (part of the brake pedal) and the turn signal switch, tail lights are controlled by the headlight switch. Track down which part isn't working right and then you'll know. BTW, I THINK the tail lights are on the same fuse circuit as the dash lights.
taillights or brake lights?it is common on many vehicles for the brake light switch (connected directly to the brake pedal) to stick over time. try gently pulling back on the brake pedal with your toe and see if the lights go off.if it is the actual taillights then i would look for a short in the wiring, possibly near the taillights themselves or right at the light switch in the cab.