496 H.O. two warning beeps when motor is not running, Oil has just been changed and full 9 qts, Outdrive oil has just been changed and full to the reservoir, coolant tank is full, Reminder, motor is not running, I am thinking a loose connection somewhere?

It could be one of 10 different things. No way to know without scanning.

496HOs only take 8 quarts of oil.

9 with filter and lines, I change it every 15 hrs.

Is it only when you first turn the key ?

Yes

If you turn the key one click the alarm will sound to let people know behind the boat it's about to be started!

Yes, I get the initial safety single long beep as you turn the key, that stops then I get a double beep and it stops.

I have a 7.4 MPI Bravo 3 and I get two beeps when I turn the key on - agree to warn people that the engine is starting. Then when I shut the engine off I get two beeps - or more like two cherps.

3pointstar

Gotcha, I would have it scanned to be safe! If no warning when running it could be sending you a low oil pressure warning till you start it and the oil pressure builds ! Just my 02

Will an OBD2 scanner work on these motors or do you need a Mercruiser scanner?