Bought 1999 Fountain with 502mpi mags. Livorsi gauges were installed and the alarm system was not hooked up so I have to constantly look at my gauges to make sure everything is okay. I noticed this after buying...

So my question is, does the alarm system for the high water temperature and low oil pressure read from the old stock gauges that had warning lights or does it read from the ECM?

I've done a search and cannot come to a conclusion. I'm new to these motors so I apologize if I'm sounding dumb.

It reads off separate sensors on the engine. It is not related to the guages at all.

Thanks. Next question is, is this one wire? What color would it be?

My my alarm lights and buzzer wires are cut. Can't find what use to connect them so I'll run a new one if I have to. My guess is that it was alarming all the time and they took the easy way out instead of fixing the problem.

this should help

Thanks. I found that on google...16 would seem to be my answer but it goes to the ECM. Not sure where it goes to the dash.

Your previous guage warning lights were part of the guage. The warning lights go off based on the guage reading only.
The Merc alarm wires are usually Tan with a Blue stripe. The diagram above shows Tan with White stripe.

That is the engine harness above. It connects to dash harness via the 10 pin Cannon Plug.

That helps out a lot. In saying that, the Merc alarm wire monitors what? Drive oil only?

low oil pressure sender to the ECM ( most install where the oil pressure sender for the dash gauge is ) and drive oil level

Low oil psi, high water temp, low drive lube

and general warning 2 -- if a transmission is in the mix.

also certain calibrations can set a horn --- 1 is soft alarm = 1 sec second on / 3 seconds off below 3000 rpms and a hard alarm = constant warning alarm above 3000 rpms when a active code is detected.