I have a 1997 Buick LeSabre. When I went to lock the doors with the remote Keyless entry transmitter the horn sounded as if someone is holding there hand on the horn.I have disconnected the fuse for the horn. The transmitter locks and unlocks the door as it should. Could this be the relay under the hood.
Some of those key fobs have a security alarm that you can activate by holding the button. This is built into the keyless system as a protection device in case someone trys to attack you at your vehicle.
Look at the owners manual or the booklet that came with the alarm to see if maybe you hit the panic button on your remote.
〉 Answered on Mar 30th, 2007 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines