1994 4.3 Mercuiser alarm constantly going off

[toddmxer733]

I have a 1994 Blue Water Monte Carlo with the 4.3 Mercuiser and just the other day after a long run across the lake when I pulled back to idle the alarm went off and I could not get it to go off. After lots of checking I took it very easy going back home. Had NO issue, ran flawlessly all the way. All indications on the dash were normal. I understand only 3 thing on this old of a boat should make the alarm sound. Low oil pressure. High engine temp. Low drive oil in the res. Oil pressure is always between 40 & 50 psi. Temp never gets over 150. Drive oil qty is at the full line.
I have disconnected each switch 1 at a time but the alarm just continues to go off. I have unplugged all 3 and still the alarm continues to go off.
Sound so simple and maybe it is but I am lost. Not sure what else to try.
Also just in case my battery voltage is good as well. 12.7 idle & 14.4 at speed.
I am going to start with the temp switch as well as the drive impellor change, as it is due anyway.
Any help would be great. Any ideas?

 

[achris]

You have a short to ground somewhere in the tan/blue wire after the buzzer. Check the engine harness, and the instrument harness.