03 sub horn stays on

My 03 Suburban horn stays on whenever I have the headlights on. I can get it to stop when I turn on the high beams. ANYONE!!!!!!!!!!!!??????????????

After market anti theft or remote start stuff?
IF FACTORY ANTI THEFT WHAT KIND?
Content or pass lock?
Have you had the body and engine pcm scanned for codes?
Does anti theft or secuirty light or check engine light stay on?
Has anything been added or repaired latley?

Sure sounds like the main grounding point that's up by the headlights is bad or faulty. With bad grounds, the voltage will try to find the path of least resistance.

I wonder if my alarm is factory.
1999, remote entry. When thew battery has been disconnected, upon reconnecting the horn goes off in short bursts. Disarms with one push of the door unlock key.

If it is factory, where might the box be?

I'm chasing the source of a battery drain issue, and need to disconnect the alarm.

Sorry for the hijack.......

Most alarms are under the driver's side of the dash and is usually about the size of 2 cigarette packs. Does your remotes say Chevy or Gm on them?

When I bought the truck there were no remotes.
Bought new original GM on ebay, and programmed it as per the instructions. Seems to work fine.

There is what appears to be a valet switch with a red light under the steering console. Switched one way the red light stays on no matter what. Switched the other way it flashes when armed, and if not armed upon exiting, it will arm itself after a period of time.

When I bought the truck there were no remotes.
Bought new original GM on ebay, and programmed it as per the instructions. Seems to work fine.

There is what appears to be a valet switch with a red light under the steering console. Switched one way the red light stays on no matter what. Switched the other way it flashes when armed, and if not armed upon exiting, it will arm itself after a period of time.
That is 100% an aftermarket alarm then that you have.

I was afraid of that. Thanks.

It's no problem. Just go dash diving to trace wires from the ignition to the alarm box. Then, just unplug the main harness then start the car. It should be OK.