Sea Ray

Do I have to open the charger? I looked in the engine bilge, I can see the main DC panel and what I believe is the charger right next to it but I didn't notice any easily accessible fuses.

Yes . Bottom portion of my charger face plate unscrews and there were two 30 amp fuses inside. Mine blew when installing my underwater lights . I presume due to reverse polarity . Worth checking out .

Ok, I looked at the charger as best I could, as it's not readily accessable and don't see a removable cover. I supplied a pic.

The charger image shows that it is providing about 10A total to the three battery banks.

Using the main DC panel in the salon and the manual BATTERY VOLTAGE TEST rocker switch selector, are both the PORT and STBD banks above 12.5 VDC? If so, there is plenty of voltage to power the lamps. If not, what are the indicated voltages on each bank?

The wiring for my 2000 380DA should be very similar to that on your 2000 340DA.

On my 2000 380DA the starboard bank powers the salon and the port powers the cockpit.

On mine, the DC lighting is protected by circuit breakers w/ these functions: FWD CABIN LIGHTING and AFT CABIN LIGHTING.

If yours is the same and part of that circuit is powered, then there is either a wiring problem or a fixture problem.

The method Sea Ray used for wiring my boat was to daisy chain the distribution, from one fixture to the next. They jammed two wires into a yellow Faston crimp connector, to continue the circuit from one lamp to the next.

It may be that fiddling w/ the wiring has disturbed the connection. If so, then replacing that Faston crimp connector might restore the connection and resolve the problem.

On my boat for the cockpit, there is a door below the wheel at the helm w/ twelve pushbutton circuit breakers. There is one circuit breaker for: LIGHTS.

They daisy chained the wiring in the cockpit the same as in the salon.

Check the connections and check the fixtures first.

The other potential issue is that Sea Ray built my boat w/o tinned wiring.

In the cockpit that copper wiring is starting to show age, w/ the copper starting to get dark. This is contrasted to the salon where it is still bright and shiny copper color.

My seat of the pants guess is that I'll get at least ten more years out of the cockpit wiring before I have to replace it w/ marine wiring.

It is possible that an abnormal exposure to the elements on your boat might have accelerated the wiring deterioration and there might be a wiring problem on your boat.