What motor and control unit are we talking about here? A model number would be helpful. There is a tilt and trim switch that has a habit of crapping out, but we need to know which one you have in order to help you.
As itsaboattime said, need to know your OB model, or at least year and HP. Then check to see if you have a 2 wire or 3 wire trim motor. I'll get you started with some info on the 3 wire motors. Much will be similar to the 2 wire motor, until you get back to the solenoid(s). If I understood you correctly, you have a trim switch at the motor, and it is working properly. That tells me that the problem is probably not related to the solenoid(s). You'll need a multimeter to do the tests in the photo below. Hope this helps.
