[pjdion]

I have a 2002 Tiara 3800 with 517 hours.  Yesterday, when I got to the boat one of the first things I do when I get on the boat is open the window vent.  Didn't open.  Blower didn't turn on. Windshield wipers didn't turn on. Hmmm. Then I turned on the key to the port engine....nothing.  Once I pushed in the battery parallel the port engine started.  However, as soon as I took my thumb off the battery parallel the engine stopped.  I did notice that all the items I mentioned earlier worked with the engine on (while my thumb was on the battery parallel).  I even turned on both engines (with thumb on battery parallel) and as soon as I took my thumb off the battery parallel the engines turned off.  I checked all the engine batteries and all registered 13.59 volts, but this was with the battery charger on.  As I did all of this I was on shore power. Any advice?

[johnhesch]

Sounds like a bad main ground to battery. All of those issues are linked to one thing: the port battery bank

[jclark003]

It could be either ground or a positive lead. First step typically is to clean all battery and cable connections. Or put your meters negative lead on engine block and positive lead on positive battery post. If you show 12V on meter it probably isn't ground so start walking your meter upstream on the positive side from battery bank to disconnect switch. It's not unusual for cable connections (positive or ground) to loose connectivity or for disconnect switches to go bad.

[pjdion]

I replaced the engine battery bank switch on the electrical panel under the salon steps.  Best if you attack it from the panel switch side and from the engine room side because of the massive amount of wires on the backside of the panel. You can order the switch on line.  Problem solved.