Where is the horn on 2002 Cadillac Deville? There is very low volume sound

the spec. is 41-47 psi at idle
http://www.ericthecarguy.com/forum/8-Service-and-Repair-Questions-Answered-Here/25682-2002-cadillac-deville-possible
fuel-pump-failure

They are mounted behind the grille or on each side of the engine compartment inner fenders.

battery voltage must be at least 12.4 volts to start. Sound horn and see if loudness is not normal, or switch on headlights and see if brightness is normal

That sounds like a flat battery. Lights and horn working are not a true reflection of the battery condition. If the dash lights dim while you try start the vehicle, it is definitely a battery low on charge. Have the battery charged or replace it and have your charging system checked out. With the engine turning at about 2000 rpm, a volt meter across the battery should read about 14.5 volts. If it is much lower than that there is a problem with the charging system.

you can buy diagram @ www.alldatapro.com (single car or volume issue depends on what you want

The most common cause of a horn not working in a car from the 1990s existing past 2010 is the horn itself not making internal contact with the horn 'motor' which makes the high and low tones one usually hears on a GM product.

I actually had this problem on a '97 Cadillac Deville Limo I bought which was not used much.

It happens to other brands, too, due to disuse.

Also, the button on the steering wheel may not be grounding the horn out to make the sound.

good luck on this one.

how do i replace the low beam lamp on a 2002 cadillac deville?

yup that sounds about likely

The click sound is the horn relay operating, it could be a blown fuse, a bad horn relay, a bad horn, or a bad ground at the horn.

Most likely problem is the fuse which controls the horn. Look in your owner manual for the page that has the fuse chart. Then go to that fuse panel and replace the blown fuse with a new one of the same amperage