Re: how do you replace the trim switch on throttle
I just went through this with my '01 Mercury 115hp. It ended up it wasn't the switch, but a bullet connector that was corroded in the back of boat. I used small cheap voltage tester and checked for current in the Pur/wht wire. The Pur/wht wire had power when I pushed the up button on the controller, but when I tested Lt/blue wire, I had no current. These wires plug into each other. (Don't ask me why). When I took the connector apart, I had a oxides corrosion that the current wasn't passing through. I cleaned the connector, and now everything works great.
What I am saiding is, it may not be the switch. So before you start tearing into the controller, check for power in your trim up wire going to your motor when you push the up button.