Installed new battery on 98 deville and the horn stays on when battery is connected

Low voltage does really strange things to the control modules, so replace the alternator, clear codes, charge the battery and drive on.

Could be a bad fuse, battery or alternator. If they went off and stayed off then it's probably a fuse. If they dim off and on then it's probably the alternator and/or battery but I would replace the alternator first.

Good luck!!

in case you didnt know there are five horns i to have a 98 deville delegance 2 are under car 1 next to the battery I honestly cant remember where the other 1s are but wen you look at the 1 by the battery look 4 4 more of those its probably a fuse or relay if they all stopped working at once. hope help.

What your hearing is the factory alarm not the horn. Connect the battery when the alarm sounds go to the drivers door lock with the key and lock and unlock the door until the alarm goes off . Then reinstall the fuse for the horn.,

I think they are in the fusebox under the hood.

Check the dynamo/generator

Install the battery by connecting the positive cable first,then the negative.If this does not work,do it vise-versa.connect the negative first,then the positive cable.If this does not work,connect the battery,and then insert the key and start the engine,if horn stops,let it run for about a minute,then turn the ignition off and remove the key.

yup that sounds about likely

sounds like a 12V drain on the system, like a trunk or glove box light that won't shut off.> Could be many. many other reasons why. The way I would find the draining circuit would be to remove the neg cable of the battery. I then would connect a 12V test light between the neg battery TERMINAL and the neg battery CABLE. With a 12V drain the light will shine. I would install into the light a 9V battery powered recepticle to hold computer and radio station memory. Then I remove fuses 1 at a time, then reinstall, at the same time looking for the 12V light to go out. Hope this helps.

don't. go get your clock spring replaced. horn will work, cruise will work and you will have no air bag light.
it is a free fix at the dealer. a 98 has a recall on this.