It sounds like the switch under the horn ring in the steering wheel is shorting out, making your horn go off. To fix it, you need to remove the horn ring from the wheel and inspect the horn switch. BUT FIRST, you need to disable the air bag by removing the air bag fuse and waiting at least 20 minutes before starting any disassembly work. You don't want to accidentally short out any wires to the air bag and have it go off in your face!

If the horn switch is bad, you will have to replace it. Unfortunately, it is a very expensive part ($294 !!!) The OEM part number is 16194554.

As a stop gap measure, refer to your owners manual and locate the fuse for the horn and remove it to keep the horn from going off. Or, open the hood, locate the horn(s) in the front of the engine compartment, and disconnect the electrical connector to the horn.

Here's the steering wheel and horn switch asssembly:

Images available only to Customers.



Here is an electrical diagram of the horn circuit for reference:

Images available only to Customers.