1990 Mercury 115 auto trimming

[Mercury115twostroke]

Hey I have a 1990 Mercury 115 inline four cylinder 2 stroke. Last time I was out, I was trimming up while on plane and when I tapped the button it came up but once I let off the motor kept coming up. It came all the way out of the water. I turned the engine off and I was able to trim back down. But right when I start the motor it trims up on its own. Trim goes up and down perfect when engine is off. The problem only occurs when the motor us running. If anyone has heard of this please help ! Thanks, Mike

 

[Texasmark]

Interesting. Trying to figure where the two circuits interconnect and have no answer other than maybe a chafed wire in the control box. The trim circuit is powered by the red wire which is 12v continuously as compared to the red/purple stripe or just plain purple wire which is switched 12v when the key is anywhere but OFF.

Up is the blue wire (blue sky...sky is up) so the blue wire is getting 12v apparently from the red/purple stripe wire. The trim circuits should have no relationship with the ignition switch, but both share the remote control physical location. That's where I'd start.