Check the solenoids in the back on the trim pump, there are 2 of them. 1 has a blue wire to it, the other has a green wire to it. Unbolt them, 2 bolts, and clean off the brass connection points, then reinstall. If that doesn't work, either one of them is shot, or it is a wiring issue on the outdrive where the trim sensors are. These have black wire running to them, they are located on the sides, near the top of the outdrive.