Join Date: Oct 2007
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Check this out!
As I indicated I fixed the problem in the OP, but decided to rewire the entire interior lighting circuit. Due to the modifications, it also made sense to re wire the neg circuit from the bow nav lights.
The new interior circuit worked perfectly, then I cut the neg wire for the Starboard bow nav (running) light. Suddenly, the interior, spreader, anchor and steaming lights no longer worked, and switching any of them on turned off the am/FM radio. If I turned the circuit off, the radio would come on in about 5 seconds.
Except for grounding at the main panel, those circuits are completely separate from the bow nav lights. Interestingly, the only light that wasn't affected was the Port bow nav light, which shares a switch with the Starboard light (of course) but is wired independently (separate hot and ground wires).
I expected that cutting the ground on the Starboard light would disable that light (of course). Why would it affect the other circuits? To be clear, this isn't a bad ground as I suspected with the problem in the OP. I kind of understand how the system would be affected when a circuit is trying to function with a bad ground. However, this was a severed ground. I would think the current on the cut circuit would simply not flow, and the other circuits could go about their business.
When I reconnected the ground on the Starboard nav light, everything functioned perfectly!
Someone please enlighten me!
Last edited by L124C; 04-24-2013 at 04:13 AM.