Alarm horn on Bullet 20XDC with 2006 225 PRO XS

Hi guys, My alarm horn quit working last trip out, does not give the 1 second beeeep when turning the key on. Bought new horn, tested & replaced, still not working. I can hear a very faint chirp when turning the key on. Had worked fine for the past 3.5 years with this Optimax. Anyone know how the alarm system is wired or ever run across this problem. Any advice troubleshooting this is greatly appreciated. Thanks

Fairly simple system.... purple wire provides 12V+ key-switched power to horn, tan w/blue stripe carries the ground signal from the PCM.

If you have a good MERCURY or QUICKSILVER horn (do NOT substitute any other brand or device)... you will need to have this checked by someone qualified to test the system.