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Horn honks if I try to drive my M3

Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
Never heard of this happening either. And yes interesting thread read. I had to laugh at picturing this and at first wondered if someone in your house with a remote key or remote access to the car via phone app was honking your horn.

Feel for you that it didn't correct itself after the update (if that's what caused it). What happens when you actually depress the horn?
Press the horn?!! Are you kidding? There's entirely enough honking as it is. Or was: see my following post.
 
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Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
Tesla Service texted me and said there was a new firmware update available and that I should download and install it. I thought, "Firmware! Yes!!!"
I installed it and I cannot adequately describe the beautiful sound of silence when I turned the steering wheel. My wife and I immediately went out for our first drive-around in our new M3. Wonderful. The car has the most solid feel of any car I have owned. I suppose it's that big battery.
I've said this before but the quality of online service I got from Tesla was without exception the best I have ever had from any help desk. They were all amazing and patient and ready to do whatever was needed whenever it was needed.
 

SMAlset

Well-Known Member
Mar 4, 2017
9,242
10,118
SF Bay Area
So glad you have peace of mind and sound now! I always wonder why one car is affected that we’re hearing about and not others. As for trying to honk I thought if not touching the horn set if off maybe depressing it would somehow affect it differently? Like reset it somehow??...not mechanical or electronics minded here obviously. :) Hope all your rides forward are nice and quiet like EVs should be!
 

Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
So glad you have peace of mind and sound now! I always wonder why one car is affected that we’re hearing about and not others. As for trying to honk I thought if not touching the horn set if off maybe depressing it would somehow affect it differently? Like reset it somehow??...not mechanical or electronics minded here obviously. :) Hope all your rides forward are nice and quiet like EVs should be!

My earlier reply to you was pretty flip. I should have said that I wished I had done what you suggested for much the reason you gave above. By the time I saw your post I had already installed the update and it was too late. I guess I should go out and try the horn!
 

towndrunk

Member
Jun 2, 2018
291
210
Fargo, ND
Tesla Service texted me and said there was a new firmware update available and that I should download and install it. I thought, "Firmware! Yes!!!"
I installed it and I cannot adequately describe the beautiful sound of silence when I turned the steering wheel. My wife and I immediately went out for our first drive-around in our new M3. Wonderful. The car has the most solid feel of any car I have owned. I suppose it's that big battery.
I've said this before but the quality of online service I got from Tesla was without exception the best I have ever had from any help desk. They were all amazing and patient and ready to do whatever was needed whenever it was needed.

So what version do you have installed now?
 

woof

Fluffy Member
Supporting Member
Apr 30, 2009
1,588
1,904
Glad it's fixed...but I'd love to know the actual cause of the glitch that software can cause it/fix it.

One totally random guess: the processor that reads the 'horn switch depressed' signal on the CAN bus was looking in the wrong slot, and perhaps was reading the 'steering wheel angle' sensor instead. So whenever the wheel was turned a bit, it would cause the processor to trip the horn relay, thinking the 'horn switch' was pressed.

Perhaps something was added/removed from the CAN bus slots, and not all the processors were correctly updated with the new locations.

Just a wild guess that might explain the described behavior.
 
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Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
So reinstalling the same version fixed your issue.

Not exactly.
The relevant change was the firmware, not the software. I ended up with the same software but new - or I assume - re-installed firmware. I believe the firmware became contaminated during a botched update. The msg from Tesla Service was, "We have sent a new firmware package out. Please install and report back." I assume the same 40.50.1 software was included and was also installed on top of the firmware. After three installations of the same software but no improvement, I was pretty sure it was a firmware problem and was excited when they sent a firmware install.
 

stonelance

Member
Jul 26, 2018
333
213
Seattle
The software updates for the car are generally called firmware. Most likely it is a package which contains multiple firmware for various components of the car. It sounds like maybe one of them didn't install correctly. I wonder if they just repushed the same package or actually hot fixed something.
 

eye.surgeon

Active Member
Nov 18, 2014
1,368
2,350
California
Thought you said reset after update was urban legend doc.
A reboot to fix a software glitch is common practice and often effective. A good luck reboot after every software update in the absence of any issues is unnecessary and basically the tech equivalent of throwing salt over your shoulder. That is the urban legend to which I was referring. It persists despite being debunked here every 6 months or so in a thread. You haven't been here long so this may be news to you. Regardless, congrats to the OP for getting the problem resolved.
 
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Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
The software updates for the car are generally called firmware. Most likely it is a package which contains multiple firmware for various components of the car. It sounds like maybe one of them didn't install correctly. I wonder if they just repushed the same package or actually hot fixed something.

Firmware is software that controls the physical object, like printer drivers controlling printers. "Software" is higher-level software that tells the firmware what to do: what to control and how much, what direction, whatever. Software may be frequently updated, firmware much less frequently, maybe never depending on the object because the physical object doesn't usually change. BIOS in computers is an example of firmware. It became clear to me that the ordinary software update to 40.50.1 had not worked and was not going to work. That's why I was so pleased when they said they had sent firmware for updating...entirely different thing.
 
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stonelance

Member
Jul 26, 2018
333
213
Seattle
Firmware is software that controls the physical object, like printer drivers controlling printers. "Software" is higher-level software that tells the firmware what to do: what to control and how much, what direction, whatever. Software may be frequently updated, firmware much less frequently, maybe never depending on the object because the physical object doesn't usually change. BIOS in computers is an example of firmware. It became clear to me that the ordinary software update to 40.50.1 had not worked and was not going to work. That's why I was so pleased when they said they had sent firmware for updating...entirely different thing.

I know what they are. What I'm saying is that the software updates for the car are often referred to as "firmware" by many people, whether they are technically correct or not. So I would not assume the Tesla person saying firmware actually meant firmware in the normal use of the word, they could have just scheduled a reinstall of the update.
 
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Gardyloo

Member
Nov 5, 2019
58
55
Little Rock, AR
I know what they are. What I'm saying is that the software updates for the car are often referred to as "firmware" by many people, whether they are technically correct or not. So I would not assume the Tesla person saying firmware actually meant firmware in the normal use of the word, they could have just scheduled a reinstall of the update.
If you need to barely press the wheel to get the horn to honk, that’s all but a guarantee it’s mechanical. The car has a simple switch for the horn like everything else, so it does not detect pressure. It has no way to know the difference between pressing hard or lightly, it just knows if the contacts are closed. The car cant sense axial load any other way.

The car has spoken...the problem was after all mechanical. You were right, ZOMGVTEK.
As I posted earlier, the problem seemed to be resolved with a reinstallation of firmware. About a week later the horn problem recurred, then went away long enough for me to get home, then became worse than ever. I called Tesla and got a mobile service appt two days later, long enough for the mechanic to get a couple of pieces of hardware he thought he might need (horn switch unit & steering wheel, I think).
The mobile service guy, Victor, was very good. He could not find anything obviously wrong and had to look for subtle things that might not be just right. Actually, the first thing he noticed was that, when he popped the airbag/steering wheel hub off, the horn gave a quick "toot," which he said was not normal. It took 45-60min, including a phone call to HQ to see whether anything like this had ever shown up on a Model 3 (it had not), before he said he was sure it was a bad horn switch unit. It was putting pressure on the horn button so that the button was tilted to the left and was only a hair from making contact even with no pressure on the button. What he initially noticed was that the gap between horn hub and adjacent steering wheel was less than normal. His idea was that a small temperature difference could cause a contraction or expansion of pieces that would bring the contacts together.
This could explain what I had experienced. The horn blowing began shortly after the car was delivered to us. It would have been riding on an open trailer so that when it sat in our drive for and hour or so, it could have warmed up or cooled down and presto! A week later when it started honking-upon-turn again as mentioned above, it was on a colder morning that it had been since we had the car. When I tried it again after several hours, the Sun had moved so it was in full sunlight, and there was no horn blowing. The next morning at home it was cool again, and more honking. All of this was subtle enough that it was not obvious, to me at least.
We had a trip of 1300 miles total beginning in a few days so I asked how confident he was of his diagnosis. Ninety-nine percent, he said. I asked, if his mother was going to take the car on a 1300-mile trip, would he let her go? He laughed. Then said, "Maybe, I don't know." I said, "But you said it was fixed? Why the hesitation?" "Well, there's that one percent."
We took the trip, no problems. While we were on the trip, Victor emailed to ask how Horatio Hornblower was doing.
During this whole affair I got nothing but the best of service from every Tesla person of which there were about eight.. I cannot recall any mechanic checking with me on whether their work solved the problem or was I satisfied. And I am 78 so that's a lot of mechanics.
I must say I do like the sound of silence.
 

sduck

Mr. Duck
Nov 6, 2017
1,530
1,595
Nashville TN
Congrats on getting it fixed! (and I was right?)

I had an acura rsx for quite a while - super reliable car, almost never had issues. But it developed a weird horn issue like yours - would toot randomly, and then one day it got started honking and didn't stop. This was in a public parking lot, and i got kind of panicked, and gave the back of the steering wheel under the dash a really good kick. It stopped, and never did it again. So I never figured out what caused it.
 
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stonelance

Member
Jul 26, 2018
333
213
Seattle
I'm so glad they figured it out! Such an odd symptom to diagnose.

I'll add, thanks for taking the time to come back and post what the real solution was. Hopefully it helps the next person running into this issue.
 

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