I have a 1999 ML430 and recently changed out my left headlight, but now my horn is not working. I have not done anything else under the hood and all the fuses are good. The horn just seems to have stopped working. I'm not sure if I could have done something during the headlight switch to disable it or what.

Does anyone have any suggestions on a possible solution to getting the horn working again, or have some insight on what may have gone wrong? Thanks in advance!

 

There is not much to horns and their operation.
I would check for horn relay (stuck in open position), check with light bulb or multimeter if you getting voltage at the horns, or if you have voltage comming from steering wheel switch to the coil of horn relay. It could be broken wire in the steering column mechanizm. Try to turn your steering wheel while pushing the horn button to see if it has any effect on it.
Bernard

 

there are 2 horns, 1 on either side of the car behind the bumper..kind of below the headlights.