I have 1988 Johnson 150, I can't get my trim guage to work. I wired it the way the factory manual said, but still don't work (guage don't move at all). My question is how to test the tilt sending unit with a dvom? I unplugged the connectors from sending unit and used dvom and have no continuity. This outboard and boat is new to me (just bought it) it had a Johnson 135 on it originally. Thanks , Jim