Hi. I have this engine too. They can have a few issues around the trim system.
What I’d do, is take the engine cover off. Then unplug each of the switch’s one by one. The plugs are down low on the port side of engine. Or you’re right, if accessing from inside the boat and you are facing aft. Then see if you can get it to work each time.
Failing that, I’d open up the relay casing for that direction of trim. You’ll find these near the top of the engine on the front end of it. Just under the flywheel removable cover. There are three relays there that look the same. The one on the starboard side is the main relay. Ignore that. The other two are for up and down. Test these across the opposing pins, horizontally. From memory they should test at 85ohms with a tolerance of 10ohms either way. Or just swap over the other one over to the suspect one. I’d also have a look at the trim limit calibration orange wire. Make sure it’s not sitting shorting out somewhere. Same for the wire that’s got a black cap on it right next to it. Check the bow trim wire hasn’t come off somehow and shorting out or loose. Think it might be blue.
What happened to mine…was that the trim wire from the remote control box trim switch, had been poorly installed and routed. It then got nipped and jammed by the movement of the throttle assembly inside the box. Caused the wire insulation to cut through to the bare wire. Terrible design.
