The Epics use a speed measurement system that interfaces directly with the Borg Warner MDDC onboard computer. Here is a picture of the computer on my Epic 22. It is located in the trunk, drivers side beside the gas tank.
Mounted to the transom are two pitot water pickup nozzles, mine are the "old" style. I carry a large straight pin to clear them. The other style have a ring on the end, they actually work differently and require modification to the MDDC programming if you change from one style to the other. Accuski can do this and including the pickups it is about 40$. They say they can turn the MDDC around in 3-4 days.
Water shoots in and does a 120deg turn and shoots up the rubber hose. Between the pitot and the computer there is a gold colored metal tube that is mounted to the inside of the hull. Water goes in the bottom and as the boat moves, a column of air is pushed out the top via a black hose that connects to the MDDC. The computer reads the air pressure and drives the gauge via servo. On some boats, the MDDC is located elsewhere, so you may have long lines. If water gets in the system, you will have a problem like this if you live where it freezes. I don't know what these are called, what they cost, or if they are specific to Toyota.
This caused a leak that was driving me crazy trying to find. Beside the tube are the sheet metal screws I used to plug the disconnected hoses. The other side works fine! My boat only has one speedo (Millenium dash)