Port Power Trim Intermittent

[Greg French]

Port Engine started to raise on its own while parking boat in slip. Could only stop it by switching off port battery. Turned battery back on and worked normally initially, but trim switch started to not work at all on engine and throttle. Switched battery on and off again and started to work again, then same problem. Took off cowling and noticed some moisture (very little) otherwise all looked OK. Anybody deal with this problem. 1998 Sailfish w/Twin 225hp Yamaha Saltwater Series.

 

[seasick]

This is a bit tough to troubleshoot. If one of the switches, or switch wiring is shorting that could cause the problem. Testing if it is the switch at the motor is somewhat easy, just unplug the switch connector assuming you can get to it and see if the problem still happens.
You can also trytapping the tilt relay on the motor with the cowling off to see if the trim motors runs. Since you say that the problem stops when you turn off the battery and doesn't occur right away when you turn the battery back on, I tend to think that the relay is bad. That is why tapping it may show that is activates randomly.