courtesy lights stay on when battery switch in "off" position

[Captain Suzanne]

We just bought a 2003 Bayliner Trophy Pro 2052 Fishing Boat. Everything works great, but the courtesy lights stay on when the battery switch is in "Off" position. I suspect this is because of corrosion somewhere in the system causing the cabin wiring harness system to remain open. Has anyone experienced this problem and where do you think we should look first to find the source of the problem? Thanks for any help!

 

[tpenfield]

It sounds like there have been some changes to the wiring, or perhaps the battery switch was added in a "non-standard" fashion. I doubt that corrosion would do this sort of thing. Do the courtesy lights turn off at all . . . Like with the rocker switch? Anything else do this sort of thing?