Outboard trimmed up on its own

[mdolesh]

Our boat has twin 300 Mercury Verados. While cruising the starboard motor trimmed itself all the way up. I turned off the motor right away and hopefully saved the impeller. However, after that it won’t trim at all up or down (at the helm control or the one back by the motor). Additionally every 2-3 min it tries to trim up again. I turned off the batteries, still does it. Disconnected the stbd battery, still does it. I guess the trim runs off the house bank. Because the only way I could get it to stop was disconnecting the house bank. One strange thing also. When it’s trimming by itself every few minutes if I hit the down trim on either the helm or the rear controls it stops the pump. Doesn’t move the motor but seems to negate the signal it’s getting. So…how do A) troubleshoot this. B) disconnect the starboard trim pump someone so I can at least use the house batteries and use the boat until I can figure this out. C) manually? Trim down the motor? Thanks for the help!

 

[Lazy Daze]

I can't help the diagnosis - other than to say that you'll probably need a Merc computer. But it would be worthwhile to pull apart electrical connectors, clean and reconnect. This will also give you a chance to see if something looks funny (electrical wires/connectors/etc).

You should be able to find the disconnect for the wiring that goes to the pump motor. I'm not sure if it's outside or inside the "hood" - but it shouldn't be hard to find. Just start by looking for wires leaving the pump area. Although I've never worked on one, typically Merc uses blue and green for up and down.

On the stbd side of the bracket, down low, you should find your manual release screw. Look for a hole with an embossed pic of an OB. Lower the engine to the angle you think is best for all around use.

 

[mdolesh]

Thanks for the advice and info. I got lucky and everything was working again...until it wasnt. But by then I was able to test all 3 switches (helm, remote near motor, and the trim switch on the actual outboard). It ended up being the switch on the outboard itself. I took it out and ordered a new one. I think it was sending an "up" signal that was overridding, or rendering inactive, the other two switches. Once I took it out the others both worked just as they should.

 

[Lazy Daze]

Good!