I have a 1998 Hyundai Elantra the signal, brake and tail lights are not functioning. I replaced the flasher fuse thingy. Can you help? I read it may be a combination switch but, I do not know where that may be located.

There are a few possible reasons why your turn signal light is not working while your brake and tail lights are functioning properly:

1. Blown fuse: The turn signal lights are connected to a different fuse than the brake and tail lights. The fuse for the turn signals may have blown and needs to be replaced.
2. Turn signal switch: The turn signal switch, located on the steering column, could be malfunctioning and needs to be replaced.
3. Wiring issue: A wiring issue, such as a broken wire or loose connection, could be preventing power from reaching the turn signal lights.
4. Flasher relay: The flasher relay is responsible for controlling the turn signal lights. A faulty flasher relay could be preventing the turn signals from working.
5. Signal/light module: Some cars have a signal/light module that controls the turn signals, this could be faulty and need to be replaced.

LED's have resistance than incandescent bulbs, that causes a problem, so best thing to do is get ones that come with the correct resistors.

Sounds like a faulty turn signal switch. If you checked all the fuses, and I would have even replaced them just to be sure. I had one years ago that looked good, but it was defective. If you need a new switch, check rocksuto.com
I find that they usually have the cheapest prices.

start by checking fuses or the turn signal relay itself

The tail light is usually a bulb with lower wattage, so it won't glow as brightly as the brake and turn lights.. There should be one or two other bulbs in either of the two tail assy's. The turn signal can use the same bulb as the brake light. If so, it's up to the flasher assy to direct the lights to both come on, and/or for one to flash if the brake and turn signal is on, e.g.. There could also be a backup light.

So if the brake and turn lights don't operate, look to the fuses, and flasher assy. for possible replacement.

IF THE TURN SIGNALS STILL WORK IN THE FRONT, THAT MEANS THE FUSE & THE FLASHER ARE OK. IF THE SIGNALS DON'T WORK AT ALL CHECK TURN SIGNAL FUSE & STOP / BRAKE FUSE. ARE YOU SURE THE CORRECT BULBS ARE BEING USED?

A bad flasher would not usually cause no brake light, the problem you are discribing sounds like it could be a bad multi function switch, that is the turn signal/hazard switch, everything you have that is not wrking, goes through that switch on most cars. Would need to look and a schematic to make sure and do some voltage checks, but that is the direction I would trouble shoot it in.

look for voltage coming to the signal switch, from two sources one live one from the brake pedal , then from the switch out

replace the turn signal switch

check relays and fuses under the hood............