What is wrong with a 1986 Lincoln Town Car if the turn signals are inoperative when driving?

First, check the fuse box, find the fuses for the turn signals, tail lights, and hazard flashers. Make sure that they are all good. Then, somewhere under the dash, at least in most cars, is a module called the 'flasher unit'. This is what actually makes the lights blink on and off. It is difficult to get these tested, but you might try an automotive electrical repair shop. Third, if none of the the previous have worked, take the car to the above mentioned automotive electrical repair shop. The problem might be in the switch in the steering column, or in the related wiring. In either case, troubleshooting it yourself can cause other malfunctions, unless you are a very proficient electronics technician and mechanic.