Tail lights. Brake lights. Backup lights. Signal lights. License plate lights.
Check the brake switch at the pedal.
either dimmer switch or blown fuse If you are saying that the tail brake lights are working but the third brake light is not....It may be a defective turn signal switch in the steering column.
Maybe it is not connected properly or you bought the wrong type of bulb.
You probably have a bad turn signal switch (inside the steering column) if this is a GM.
Try checking the tail light relay.
This usually means a bad or wrong bulb in the tail lights
The bulb is burnt out. If the problem was a fuse, then all brake lights and probably the dashboard lights would be out as well.
There could be a severed connection somewhere along the line, or it could just be a blown fuse
Look for a fuse labeled TAIL LIGHTS. There are 2 separate circuits, one for brake turn and flasher and the other is for tail lights.
The problem points to the directional/lights and hazard switch. The brake light wiring is part of that circuit.You can buy the switch after market it is about $70.00.
See sources and related links below for 1993 Dodge Shadow tail light, brake light and turn signal light bulb part numbers.