Please help me stop this horn!

[Pounder78]

1993 75HP Merc outboard with oil tank mounted inside the cowling. When the key is turned on there is the usual 3 second beep to let me know the system is functioning. Without starting the motor there follows a continuous beeeeeeeep usually at a little lower volumn. I have taken the remote off but left all electrical hooked up. When it is making this noise the purple wire to the horn shows 12v and the brown wire shows 5v. If the motor is running it does the same thing. I've unhooked the temp sensor but the noise remains. Motor not running hot, just annoying. Any help appreciated.

 

[racerone]

Possibly the horn itself is bad.

 

[Pounder78]

Possibly the horn itself is bad.

Thanks racer one, it's looking like horn or maybe the electronic control module.