I just purchased a 2000 S4 and am having trouble with the horn and alarm. When the car is off, the horn will not honk. When I turn the alarm on, the horn will not honk. I tested the alarm, and it did not honk, but the lights flashed and the car would not start. The horn works when the car is on or started though.
Anybody have any ideas what the problem is and how to fix it? I appreciate the help.

 

Are you referring to the horn on the steering wheel or the horn that sounds when you lock the car? There is a separate horn for the alarm system which is the horn that sounds when you lock the car and when the alarm sounds and it is located in the trunk on the driver's side behind the carpet just in front of the storage compartment. It may be unplugged.

 

Thanks for the advice. I checked the alarm and it appears to be plugged in.
To clarify, the horn, on the steering wheel, does not work though when the car is off and it does not sound for the alarm. Any suggestions on what I need to do to fix this?

 

the steering wheel horn wont work unless the key is in the on position, my guess is just to avoid those pesky little kids honking the horn when their parents left them in the car to go shopping(guilty as charged) or those little dogs from honkin too when they climb all over the steering wheel. i know in my old bmw if you pushed both the lock and unlock button at the same time for a few seconds it would disable the beep when you lock and unlock the door and then to make the beep sounds again you just press and hold the buttons again. the alarm would still sound tho if you opened the door.. you could try it tho and see what happens?

 

Yeah the horn on the steering wheel is normal, the alarm horn is located on the back left of the trunk behind the carpeting if you want to take a look at it.

 

Thanks for the input. That info clears up the "issue" with the horn not honking when the car is off.
I tried pushing both the lock and unlock buttons on the remote and it did not work. The alarm does not sound when tested (the lights flash and the car won't start like it's supposed to, though). I did see the alarm box and plug on the bottom of it in the trunk. It appears that it is all plugged in properly. Does anybody have any idea of what I should be looking for on or in the alarm that's in the trunk?
Thanks again for the help.

 

hmm fuse maybe?

 

I would disconnect the horn on the left side of the trunk (i say the left side again becuase you said alarm box, so you might have found the control module on the right side). There is just two wires going to the horn, constant - and pulsed + i believe.. I would use a multimeter to see if the horn is getting power.