Electrical question

[Mariah1]

7.4 Mercruiser in a 22' Mariah. 2000 era. Very low hours and stored indoors.

Periodically some of the electrical systems fail to operate. The boat has dual batteries and a Minnkota shore power charger that charges both. The boat has a battery cut off switch that I turn off after each use.

I changed both batteries to X2 dual purpose AGM. One time everything will work fine, another time I have no captains call (no power to solenoids), several of the dash switches (depth, blower, bilge, lights, etc) don't energize anything. Oddly enough I have wiper, power seat, radio, hatch.

The engine has always fired up immediately and reliably.

Could it be the battery switch? Could it be a voltage regulator? I've traced wires the best i can but I'm admittedly no expert. What's frustrating is the intermittent nature of the problem.

Any advice is apprecialted.

 

[poconojoe]

Loose or corroded connections?
Especially check grounds.

Bad ignition (key) switch? Maybe power is not passing through every circuit of the key switch at times.

I would go through every connection I could find throughout the boat and make it all clean, shiny and tight.

Use dielectric grease when assembling connections for better conductivity and protection.

However, it could beyond my scope of knowledge and be more complicated than that.
Hopefully the experts here will chime in on other possibilities.

Good luck and keep us posted.

 

[tank1949]

Buy a good multimeter and test while a friend wiggles wires. If saltwater boat, look for green oxidation on wires