W124 E300D Horn Honking when Driving

[texas993]

So it's pretty cool. I was driving my son to school in the E300D this morning and the horn started honking all by itself. Nice, huh? It didn't embarrass him, wake the neighbors, surprise people....

So, how do I fix it? Based on a google search, it doesn't seem that common on this car.

 

[gerryvz]

Were the lights blinking at the same time?

Check the fuse on the horn circuit. Check the horn wiring visually up front by the fans to ensure that it is physically not compromised (i.e. grounded or two wires making contact).

One common cause for the horn to blare is that the factory alarm that is failing -- this is common once the factory alarms get to be 15+ years old. Usually it beeps (honk-honk-honk) and the lights flash on and off.

Lastly, you'll need to pull the airbag (disconnect battery first, and unplug airbag red plug under passenger foot-rest and carpeting) and check out the wiring around the horn ring ... again a physical check for compromised wiring. Check the horn switch behind the airbag for proper spring action so that the circuit is interrupting properly.

Report back once you do those inspections.

If it's the factory alarm, which I am 90% sure that it is, you can (and most people do) disconnect it by removing the two plugs that connect to the black alarm box in the passenger footwell. The one that has the white "Becker" sticker on it.

Cheers,
Gerry

 

[texas993]

Thanks Gerry. It wasn't the alarm as there were no flashing lights. It happened for the first time yesterday when my son and I were installing a newly acquired JY impact strip on the front bumper. In order to get a little more room, we turned the steering wheel without the engine running (without power assistance). Maybe we forced it a little too hard and the horn ring was slightly bent. It beeped a couple of times while turning the unassisted steering wheel. I assumed that my son was bumping the horn button.

I am going to drive it a bit more today to see if it keeps up. Then I will do as you advise. Thanks.