This is a non-computerized dash is what we gather from your post. There also is a possibility that this boat was altered and things are no longer in the format it was manufactured 31 years ago.
The red wires jump across both middle posts and positive power connects through the in dash circuit breaker, which should be in a row along the switch bank. The brown wires, one striped, go to the bilge pumps and are on opposing sides of the switch. There also is a black ground wire that only provides negative power to the small indicator light inside the switch.
The brown wires feed manual pump operation on one side and automatic for both pumps on the other side of the switch. Rocker switches work opposing, so when the button is pressed down one direction, it is contacting the opposing posts inside the switch. Thus driving power to the accessory (bilge or auto). Both bilges are either auto or manual on all Bass Cat models.
It sound to us like a bad switch and this should be a McGill brand switch, which is no longer made. Remove the switch carefully by depressing the end tabs that retain it. Then on a large flat surface, you can carefully pop the end tabs and take the switch apart. Inside you will find that the switch has hard contacts riveted through the back side that will be blackened, a full silicone white boot, those two contact bars with contacts, and striker arms that have two small pins, with springs driving force on the contact bars when the switch is rotated (rocked).
You can lightly clean those contacts some with a small brush, emory or screwdriver. Reset the contact bars, carefully replace the silicone boot around the pins and hat if you removed it, that’s carefully on the indicator light. The silicone boot will be fragile. Now re-insert petroleum jelly inside the switch as this gives it moisture protection beyond the silicone boot. Humidity tends to develop inside that switch from the atmosphere cooling abs heating, plus the sealed switch retains its own atmosphere. You can pack the petroleum jelly liberally to coat everything and this prevent mineral transfer in moisture, that causes the indicator lights to glow when powered off.
Replace the switch and rewire it on the same profile, being sure you get the negative (black) wire on the proper post. Brown on one side, striped wire to the automatic on the opposing side. The wires will be placed opposite of the side auto and manual are on the dash assembly.
Check operation and resume.
If the McGill switch is beyond repair, then you will have to mismatch this switch with a Carling or if your extremely lucky you may find one on EBay, as they have not been manufactured in over 20 years. Before todays Carling switch, this was by far the best switch of its time, for moisture prevention in a marine environment.
BCB
Written with assistance of AI
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