Make lights flash and horn honk when turning alarm on and off

Possibly an errant theft alarm??

Replace battery in remote.
Check wires inside of the boot in the door jam (slice hole in boot or pull out of one end. Check wires carefully for bubbles and weak spots from cracking.
Check wires inside door jam or under dash to left hand side carefully with flashlight for bare wires shorting. Feel free to move things around under there a bit to see if things are shorting or what have you.
The fuse box under the hood - inspect underneath of it for corroded wires and or contacts - may take a bit of work to remove it from car.
See if alarm is cleared by using drivers door key as there is a switch in there for the alarm. If this is faulty then this could be your problem beyond the wires in the door jam perhaps.
You have a short or broken wire or this switch in the door is bad.
These are some suggestions of where to start.
Do it in order of easiest but I suggest the door jam wires inside boot is most typical problem especially in colder climates like here in Canada East as the wires freeze and crack after a while.
May or may not be your problem but options.
Let us know with feedback about your progress or solutions plz.

take it back to dealer you bought it from

holdboth the lock and unlosk buttons on your remote simultaneously for about five seconds until the lights flash and horn chirps.that should do it.if not i believe these models used a separate horn for security system.possibly fuse for this horn is bad or the horn itself is bad.to see if this horn works lower drivers window.stand outside vehicle and lock doors with remote.wait about a minute and reach in window and MANUALLY unlock and open door(do not use power door lock button)this should cause the system to activate...horn should beep and headlamps should flash.if horn beeps try my first suggestion.if it doesnt beep and just the head lamps flash check fuses and horn for security system.

Try unlocking the driver side door manually with the key. This works on some car alarm systems.

I had this same problem just today.Hhowever, I had the remote in my hand and it would not stop the honking!. Since I could get into the car, I released the hood, opened the master fuse box on the left side, and pulled the fuse labeled "Horn Relay".(On the upper left, there are three large, black, square fuses, it is the third and is labeled in the lid). I waited ten seconds and put the fuse back in, no more alarm, no more infernal honking.

disconect the whole alarm factory 1s a bad

try honking the horn normally with horn button <key must be on> if horn works it is in the programing for comfort and convieniance system if no honk it's just the horn or wiring to horn.

there are two seperate horns