Same here, on our model Mainship they were originally open/empty, for future expansion. Now they operate the underwater transom lights which the previous owner added. Oddly, on our model I also have a trim tab rocker switch but it doesn't go to anything. Our boat doesn't have trim tabs (and even with the 454's I'm not going to be pulling water skiers anytime soon so I don't think they'd be much use anyway). I remember during the sea trial we kept pressing the switch to see what they did for the feel or the angle of ride at high throttle. Couldn't feel any difference at all so I thought they maybe didn't work. Well they sure didn't -- because the boat didn't have trim tabs! I guess Mainship liked to cover future upgrades.