How do you test them? My k-plane goes up but not down. I reversed the blue and the green coming off the pump motor and the tab would then go down but not up. Does this mean the solenoid for the down side is bad?

That's a good assumption. I would change them all by the way. It's obviously more money but you definitely do not want a trim tab to malfunction at high speed.

Just changed 2 of the six solinoids on my boat. They have gotten progressively worse as time goes on. Change both of them. I did and now the tab functions perfectly. So good in fact that I just bought two more to do the other tab that just sticks ocasionally.

Ron

Thanks guys, it looks like they are only around $20, so I will buy a few.

Check brakers and there conections