W222 Horn Issue (Mercedes Can't Figure It Out!
07-25-2023, 05:43 PM
#1
Junior Member
Thread Starter
W222 Horn Issue (Mercedes Can't Figure It Out!
Good Evening,
I have a w222 with 69,000 miles. Last summer, almost one year ago to the day, the horn started to get weaker when the AC was on and the car would go on long trips for 30-40 minutes. Then the horn would completely die out, and this includes the horn chirp when the car is locked. I would have to leaving it to sit running, with no AC on for about 10-15 minutes in order for the horn to gradually come back. Brought it to Mercedes, they had it for 3 days and couldn't figure it out. They said they hooked up some tool and activated the horn from the machine, and the horn worked, but when the pressed the steering wheel the machine said the horn is firing, but didn't hear it. Put a new relay, cleaned the contacts, all good for almost a year.
Yesterday, I was outside sitting in the car wit the AC for about an hour, having a phone call, and locked the car after I was done..all fine. Came back about an hour later, and the horn was totally gone. I drove home with no AC and the horn never came back. This morning I called my independent mechanic and he said bring it in tomorrow. I let the car sit for an hour today running in the morning, the horn came back, and then once I shut it off, locked the car, the horn chirped. After 10 minutes, and testing it, the chirp was out again. All day I drove with no horn, and when I got home and had the car sit stationary with the AC on, the horn gradually came back. Again, locked it, and it was fine. Just tested it again 15 minutes later, and the horn is gone.
What the hell could this be? Seems like it's getting power drained somewhere. I hope it's not a big problem!
I have a w222 with 69,000 miles. Last summer, almost one year ago to the day, the horn started to get weaker when the AC was on and the car would go on long trips for 30-40 minutes. Then the horn would completely die out, and this includes the horn chirp when the car is locked. I would have to leaving it to sit running, with no AC on for about 10-15 minutes in order for the horn to gradually come back. Brought it to Mercedes, they had it for 3 days and couldn't figure it out. They said they hooked up some tool and activated the horn from the machine, and the horn worked, but when the pressed the steering wheel the machine said the horn is firing, but didn't hear it. Put a new relay, cleaned the contacts, all good for almost a year.
Yesterday, I was outside sitting in the car wit the AC for about an hour, having a phone call, and locked the car after I was done..all fine. Came back about an hour later, and the horn was totally gone. I drove home with no AC and the horn never came back. This morning I called my independent mechanic and he said bring it in tomorrow. I let the car sit for an hour today running in the morning, the horn came back, and then once I shut it off, locked the car, the horn chirped. After 10 minutes, and testing it, the chirp was out again. All day I drove with no horn, and when I got home and had the car sit stationary with the AC on, the horn gradually came back. Again, locked it, and it was fine. Just tested it again 15 minutes later, and the horn is gone.
What the hell could this be? Seems like it's getting power drained somewhere. I hope it's not a big problem!
07-26-2023, 01:22 PM
#2
Senior Member
auxiliary battery? I've had the strangest things happen on my range rover and found the aux battery was failing - and once replaced - all the electrical gremlins were fixed....
