Horn toots twice after startup - what's up?

[Doug Hilliard]

OK, this has been going on for a couple months I guess. Sometimes after I start the car, the horn will do two short toots (love that technical term!) and I have no idea why. Someone suggested to replace the battery in the key fob so I did that and no change. It doesn't do it all the time. Anyone else have the issue?

[vert]

Not sure on that. I know that if you try and lock the car with a door open the horn will honk two quick times.

[polo]

You don't have an aftermarket alarm do you?

[I12XLR8]

Are there cute girls walking in front of the car when you start it? ;-P

[J Wikoff]

Not sure on that. I know that if you try and lock the car with a door open the horn will honk two quick times.

Mine honks 5 freakin times if I do that. I really wish I could turn that off.

OP: Maybe that means your dual purpose horn/blinker fluid is low? lol I got nothing.

[Panzer Leader]

Thats the automatic horn that tells other cars to get ready to get out of the way.LOL

[Doug Hilliard]

LOL! Love the creative responses! I don't have an aftermarket alarm. I haven't figured it out so just thought I'd throw it out there...still working on it!

[todds87ss]

check your setup. (settings?)

[Doug Hilliard]

check your setup. (settings?)
Not sure what you mean. Can you elaborate?

[GRRRR8]

I have seen a weak battery for the car cause this in a few different GM models.

[Crazy8]

I thought it meant your alarm was set off while armed?

[Doug Hilliard]

I have seen a weak battery for the car cause this in a few different GM models.
Thanks; the battery is at 90% per the DIC. I do get a fault on the TPMS system after I've been driving a few minutes but the horn thing only occurs at start-up and the system fault for the pressure monitor system only shows up after a good 15 minutes or more of driving.

[GRRRR8]

I thought it meant your alarm was set off while armed?

Correct. When the amps get too low in the battery it seems to cause some havoc in GM cars that have have a lot of gadgets.

[smso966]

Low voltage makes electronics go crazy and send all kinds of bad data. Get your battery properly tested. It's free at alot of parts stores.

[texn884]

The car is farting, need to release some pressure before you go WOT as you leave the driveway or parking place.

[Steve GT]

If the battery checks out then start checking your grounds. When we left the ground next to the rotofab box off after the cam install my horn was going nuts.

[Doug Hilliard]

Sounds good; I'll have the battery checked out. It's over three years old now and I know there were issues with some of them anyway. Mine has died twice just sitting for a few days. Thanks for the input guys!

[TurboMike]

You have a TPMS problem. Doesnt the car honk twice as its learning each tire pressure? Did you shut the car off in the middle of a TPMS learn session? Does one parking light come on when the two honks happen?

[Doug Hilliard]

You have a TPMS problem. Doesnt the car honk twice as its learning each tire pressure? Did you shut the car off in the middle of a TPMS learn session? Does one parking light come on when the two honks happen?
Yes it does but I've had the TPMS reprogrammed at the dealer with the computer tool and this is still happening from time to time. I don't know about the parking light as the car is usually moving when the horn honks like pulling out of a parking place. Maybe next time I'll stop and check the light.

[GAG8]

Yes it does but I've had the TPMS reprogrammed at the dealer with the computer tool and this is still happening from time to time. I don't know about the parking light as the car is usually moving when the horn honks like pulling out of a parking place. Maybe next time I'll stop and check the light.

Try to do a relearn and see if the issue goes away:

1. Set Parking Brake
2. Turn the ignition ON but don't start the car
3. Hold the Lock / Unlock buttons on your Key FOB until the horn beeps twice
4. Starting at the left front (light will be on) let air out of your tire until the horn beeps
5. Move to RF tire and continue following marker lights around the car until the process is complete
6. Re-Inflate all tires to desired air pressure (36 psi or your preferred)
7. Try remote start to see if the issue is resolved

If you cannot complete this process then you may have a bad tire pressure sensor or other TPMS problem that you should probably get checked out.

[hayabusa160]

the horn would honk when i turned the headlights on because i left the ground by the intake loose so check that out.

[bjhayes]

My car will sometimes instantly lock all the doors when I start it. Despite my settings it does these every few weeks. But I have not had the spontaneous honking (yet!)

[GAG8]

My car will sometimes instantly lock all the doors when I start it. Despite my settings it does these every few weeks. But I have not had the spontaneous honking (yet!)

Transmission in Park switch issues?

[GXPaycheck]

That's the "my car is tooooo fast" alarm. ;-)

[Doug Hilliard]

that's the "my car is tooooo fast" alarm. ;-)
lol!!!

[bjhayes]

Transmission in Park switch issues?
That's what I believe it is but good luck getting it to happen for a dealer... Just another GM-ism...

[todds87ss]

Not sure what you mean. Can you elaborate?

Nevermind. I went through all of the settings and nothing will cause this. I would think that a tech2 scanner would be able to identify what is causing this (some type of BCM malfunction).

[Doug Hilliard]

Nevermind. I went through all of the settings and nothing will cause this. I would think that a tech2 scanner would be able to identify what is causing this (some type of BCM malfunction).
OK, thanks for checking all that stuff out!

[Doug Hilliard]

Well I had the battery checked and it's fine; lots more cold cranking amps than spec'd. I thought maybe whatever it was had gone away for some reason as it hadn't happened for about a week then last night, cranked it up, get ready to back out of a parking space and the horn blows twice! I'll check the grounds when I get a chance but the mystery remains!

[G8Lady]

Curious if you ever figured this one out, it's happening to me now..

[G8Lady]

You have a TPMS problem. Doesnt the car honk twice as its learning each tire pressure? Did you shut the car off in the middle of a TPMS learn session? Does one parking light come on when the two honks happen?

I'm having this problem now, and one parking light does come on for me when the two honks happen. What does this mean?

[Doug Hilliard]

Curious if you ever figured this one out, it's happening to me now..


I'm having this problem now, and one parking light does come on for me when the two honks happen. What does this mean?

Not conclusively although it does seem to have to do with the TPMS system. If I relearn the sensors it seems to be ok for some time, then will come back once in awhile. No idea how to permanently address it. It makes me wonder if some sensor is going bad (battery dying) as I know the batteries don't last forever and they are getting to the age where they may be getting weak. I have had to replace one already.

[proto]

Not to resurrect an old thread but I am having the same issue now with the TPMS. I had 4 "new" sensors installed a while ago and one of them wasn't in a package when I received it. Put it in anyway and had issues after a few months. Just bought 4 brand new ones and all were new this time. Followed the procedure to get them to learn the location (followed by the beeps and market lights illuminating at each step). The car accepted them and all 4 show up on the cluster. Now when I park the car and start it up it beeps 2 times occasionally. I'm at a loss as to why it would do this. I'm going to go thru the engine bay again and check the grounds.

[Doug Hilliard]

Not to resurrect an old thread but I am having the same issue now with the TPMS. I had 4 "new" sensors installed a while ago and one of them wasn't in a package when I received it. Put it in anyway and had issues after a few months. Just bought 4 brand new ones and all were new this time. Followed the procedure to get them to learn the location (followed by the beeps and market lights illuminating at each step). The car accepted them and all 4 show up on the cluster. Now when I park the car and start it up it beeps 2 times occasionally. I'm at a loss as to why it would do this. I'm going to go thru the engine bay again and check the grounds.

I've not solved it; mine still does it!

[Purf]

Not conclusively although it does seem to have to do with the TPMS system. If I relearn the sensors it seems to be ok for some time, then will come back once in awhile. No idea how to permanently address it. It makes me wonder if some sensor is going bad (battery dying) as I know the batteries don't last forever and they are getting to the age where they may be getting weak. I have had to replace one already.


For whatever it is worth -- I had two new tires installed outside the dealership and the existing TPMS sensors were placed in each of the two new tires. My TPMS ocassionally came on as a "fault" and none of the tire pressures showed up on the dash display. I went to the dealership and they rebooted the TPMS today. The rebooting was evidenced by two beeps of the horn and two blinks of the lights initially and each time the sensor was placed on each of the four tires. Hopefully, that solved the problem. During my discussions with the tech, he stated that sometimes weird things happen with the TPMS when the TPMS battery starts to get low. Just sayin'.

[Markmsf3]

Not to resurrect an old thread but I am having the same issue now with the TPMS. I had 4 "new" sensors installed a while ago and one of them wasn't in a package when I received it. Put it in anyway and had issues after a few months. Just bought 4 brand new ones and all were new this time. Followed the procedure to get them to learn the location (followed by the beeps and market lights illuminating at each step). The car accepted them and all 4 show up on the cluster. Now when I park the car and start it up it beeps 2 times occasionally. I'm at a loss as to why it would do this. I'm going to go thru the engine bay again and check the grounds. I'd bet money you have a battery dying in a sensor.

[proto]

I'm having the same issue now with mine. Replaced the TPMS sensors last year and that didn't fix it. Just had them replaced again and it keeps beeping as I get reasy to leave the drive. It also does it when I come to a stop sometimes. I read in another post that the issues could be a power wire running across the deck. I was pulling power from the driver side rear up top to power the reverse camera. I removed the wiring now and still have the issue. Did you ever find your issue Doug?

[Doug Hilliard]

I'm having the same issue now with mine. Replaced the TPMS sensors last year and that didn't fix it. Just had them replaced again and it keeps beeping as I get reasy to leave the drive. It also does it when I come to a stop sometimes. I read in another post that the issues could be a power wire running across the deck. I was pulling power from the driver side rear up top to power the reverse camera. I removed the wiring now and still have the issue. Did you ever find your issue Doug?

Not really. I did have a TPMS sensor fail and I expect it was the battery. I still think it is probably the sensor batteries getting weak but don't know for sure. It still does it from time to time with no known obvious cause. Wish I could help! Wish I could get rid of it, but it's not worth it to me to pay for all new TPMS sensors all the way around to see if that's it!