2002 33' express spreader switch wiring

[ninajoe]

I need to replace a missing cockpit dome/spreader light switch assembly. It has 4 wires hanging down, red, black, blue and grey.. I see that the red wire is +12v, the black wire is ground,(-12v), and if I connect the red +12v wire to the blue wire the spreader lights come on. My question is what is the grey wire for? Thanks in advance.

 

[ninajoe]

I found that the grey wire goes to a fuse panel above the cockpit. It had a blown 10 amp fuse. It appears the the courtesy light switch and the spreader light switch have independent +12v sources.