Horn Honks when battery is connected on Toyota 4Runner?

This problem is noticed many a times.
The horn starts honking with out any reason.And you need to disconnect battery.If you reconnect battery the horn starts going ON.
It appears that you might have a factory alarm system on this vehicle. Try cycling the key in the ignition from lock to on (not to start) 5 times. This procedure is built into the factory system if the battery in the remote goes dead, or if the remote gets lost.

This procedure should help you out.Otherwise horn connections needs to be inspected,something is getting short in horn connecting wires.