Warning Buzer Problem 1994 Baja 272 .. 454 Mercruiser

Down to my last issue hopefully. Not totally new. Got everything running fine. Engine runs cool. Temp gauge works ..holding under 100 degrees using muffs, exhaust manifolds just warm . No smoke or oil burning. Oil pressure gauge reading good.....
BUT..at start the warning buzzer goes on and will not go off. Ran for 10 minutes and did not go off. Then after I shut down the engine and started it back up after a minute or so buzzer did not go back on. Anyone know whats up with that??
Manual says the buzzer is for three things .. H2o in cooling system too hot..not buzzed from start up .. engine oil pressure too low.. good pressure ..running about 40 psi after start up... trans fluid too hot ... no trans so not an issue ..

The temperature and oil pressure readings come from variable resistance sensors, the oil and water alarms come from on/off switch sensors, typically located very nearby the variable resistance sensors. On many engines this is wired (in series) so that a bad connection anywhere or at either sensor will be interpreted as an alarm condition.

Of course now its not buzzing.....

Check for loose and or dirty connections as sandkicker sugested. I believe sensor buzzer can be tested by grounding wire going to it to clean ground!