I have the same engine, and don't have this problem. I'm guessing that (1) if your batteries show an output of 12v, they are pretty well discharged. Fully charged batteries should show a charge of 12.6-12.8 vdc when not under load. (2) your wiring harness may developed some impedence, which happens over time. The hard starting in cold weather suggests that not only may your batteries be undercharged, they may not be able to put out the needed cranking amps for starting -- cold weather just makes it harder for such batteries to perform. You may want to start by having your batteries load tested (most West Marine stores can do this or most auto service stations). You also may want to check your wiring harness to make sure that all the connections (and there typically are far too many...and each reduces amps needed for starting) are bright and tight and that your wiring itself is not drawing off current due to internal corrosion. Lastly, but importantly, the buzzer is the oil pressure sensor. Make sure you don't have an oil leak and that your engine oil is filled to the proper level. Hope this helps.