Mast wiring on C30
My previous 1984 C30 had the halyards inside the mast. At the base of the mast on the starboard side is an opening with two blocks. You can remove the unit easily to access the wiring inside the mast. There is a 4 wire plug you can pull out through the opening and unplug to check current. One contact is ground and the others are steaming, anchor and spreader lights. Turn on the switches to all and check with a voltmeter to see if voltage goes to all wires. If so, the problem is higher up. Sometimes this plug has corrosion, so lightly sand the contacts.