MERCURY WARNING SYSTEM PROBLEM

I’ve got a 90hp 2 cycle Mercury on my H-51 Alumaweld with a Merc Commander 2000 remote control. When the key is turned to the ON position there should be a momentary beep signaling the warning system is OK. The warning system monitors oil level and head temperature and when I simulate an alarm the warning beeper sounds so it is OK. The wiring checks against the schematic and it has a new key switch. Anyone run into this problem - I’m plumb out of ideas.
Thanks - Mike

On my 1994 60/45 jet I had the same problem where the warning would go off constantly. I thought it was the overheat warning sensor so I bought a new one and still got the warning. I don't run the oil injection so the oil tank is empty and disconnected so I know it's not the oil level. In the end, I'm pretty sure it's the overheating/low oil unit that went bad but it runs cool and pumps water fine. So I disconnected the unit altogether since I always watch the telltale to know it's pumping fine. Your overheat/low oil module might be bad or it could be the low oil sensor or the overheat sensor so you may want to test each of those before assuming it's the module. You can disconnect the wires and run it, but you need to make sure it's not a serious problem first. I have a new oem mercury temp sensor if you're interested and it's the same part number for your motor (#78799 2). If the water coming out of your telltale is really hot, then you might have another problem with the cooling so check that. What year is your motor?

Thanks JL8Jeff - The problem is the warning horn does not beep briefly when you turn the key from Off to On. This is to let you know the warning system is operating.
Mike

Ok, I was reading it wrong. I have my oil tank wire disconnected (I removed the oil pump and run premix) and my overheat sensor wire disconnected and I don't get any beep when I turn the key on. So maybe one of your wires is disconnected or shorted out.