My rear defroster on my 02 Sonata is not working. There is a wire plug under my front drivers seat that is not plugged into anything. Could this be the answer? If not, what is that plug for? I can't find anywhere it could go, unless I just did not see it. Thanks in advance!
Does the on/off lamp on your defogger switch illuminate? (Check with the car running. It won't turn on unless the car is running.) If not, start by checking your fuses. If so, turn it on and go to the rear glass and check to see if you have 12V between the two terminals. If you get the 12V, you're looking at a grid problem. If you don't, you're looking at a problem elsewhere. You'll probably want to get a schematic if that's the case.
Most frequently, one of the wires is disconnected or the tab came off the window.