Larson Senza: Intermittent audio alarm

I have a 2004 Larson Senza 186 I/O (Mercruiser) and this summer my ignition switch literally fell apart in my hands. That same day, my electrical warning siren started to intermittently sound on and off. Not sure if they are related but while I was fumbling with the switch, the siren was on for about 25 minutes straight since the switch was stuck in the on position (engine was off). I replaced the switch and this didn't seem to fix anything. My gages all look okay and there are no obvious sights/sounds/smells eminating from my engine or lower unit. Siren seems to be worse at lower speeds and is more likely to go off when cruising slowly through channels and/or right after launch when the engine is first turned on. At higher speeds it is rare to hear the siren but when you do, it is usually for a very short time (<1s).
There is no pattern or rhythm to the siren sounding. It will be fine for long amounts of time then go on for a while, sometimes a few seconds sometimes for a minute or longer, then turn off. A service dealer suggested I try replacing the siren itself but I hate to go shotgunning parts without some debug. Any thoughts or ideas?

By the way, my engine is a carburated V8, GM build.

Re: Larson Senza: Intermittent audio alarm

Are you sure you connected all the wires to the new switch properly? The alarm is triggered when the oil or volts gauges are out of range. This happens when the ignition is on and the engine is off.

Also check the ground. You may have accidentally pulled on a ground wire (probably one of those blue taps) so it's making intermittent contact with ground. The alarm needs a solid ground in order to compare proper voltage with a fault.

Re: Larson Senza: Intermittent audio alarm

RickJ6956, first THANK YOU so much for responding.

Regarding the switch, I am pretty sure I got the wires connected correctly. I can turn over the engine and everything else works properly. I literally disconnected wires from the old switch and added to the new switch on a "disconnect 1, connect 1" basis to make sure that I didn't get anything wrong. (Also disconnected the battery when I was doing all this.) All the screws seem tight and secure.

Regarding the ground connection on the alarm, I haven't yet touched the little siren so I am not quite sure what you mean there. When you say "check the ground" where are you suggesting I check it?

Re: Larson Senza: Intermittent audio alarm

We have a 2006 LARSON 204 Escape f/s with a 5.0 Carb I/O. From the first time out this year, we had a audible alarm go off intermittently, at low speed, and at high speed. Never a solid sound, NOR for more than 30 seconds.

I took the tech from the shop with me on a ride. (Our dealership is on the lake where we go).

ALL guages were fine. (I even changed out the impeller). ALL fluids were up to the proper levels. The lower unit was fine.

The tech told me that he had "4" more LARSONS of various models, and he told me that they needed new harnesses to the alarms. There was a flaw of some sort in them
SO, when our boat goes over this fall for winterization, LARSON/Mercruiser is going to pay to replace them.

Hope this helps !!!!!

P.S. 2 of the boats that had the harnesses replaced, said that the noise went away !!!!!!!!