Trim Motor stuck on down will not shut off

My 90 HP Merc trim system suddenly is stuck on (running) in the down position. The elect trim motor will not shut off and will not trim up. I have eliminated the cowl switch and throttle trim switch. Now assuming a bad down relay bad solenoid or short in the electrical motor.

Any suggestions on my next move?

Guess I was lucky the motor did not short in the up position. Would have been a long tow home.

Re: Trim Motor stuck on down will not shut off

My next step from what you said, assuming you have a battery switch, would be to pull the wire from the solenoid to the trim motor, turn on the battery switch and see if you have control voltage to the soleniod coil, this would be the small wires. If you have voltage there then you need to trace back to your control switches to see where the problem is. If you don't have control voltage but do have voltage to the terminal that goes to the trim motor then most likely the soleniod contacts are stuck together. You can also check for continunity across the battery side of the soleniod and the motor side with the battery switch turned off.

Hope this helps. Durwood

Re: Trim Motor stuck on down will not shut off

Thank Durwood
I dont have a battery switch (on the to do list) but I should be able to work through your steps by disconnecting the battery cable or the main trim connector near the engine trim switch. I had to disconnect the cable connector at that point in order to shut the motor off and prevent burn out while I was out at sea. Fortunately I have been able to have a good weekend with trim full down.

Re: Trim Motor stuck on down will not shut off

Yep..........soleniod or possible short..............you can try taping the soleniod sometimes it will release...........I seen starter motors on engines do this too..............

Re: Trim Motor stuck on down will not shut off

If you disconnect the cowling switch the trim will not work remotely from any switch. If it runs when disconnected then it is a relay or a solenoid. Theres no power going to the trim motor unless the relay or solenoid is engaged (closed). The problem is not with your trim motor unless a wire has worn through and is shorted to a hot lead somewhere.

Most boats have trim switches at the controls. I've had the trim switch in a control stick and cause a similar situation. Not sure what you have but I'd be checking switches first.

Re: Trim Motor stuck on down will not shut off

sschefer said:

If you disconnect the cowling switch the trim will not work remotely from any switch. If it runs when disconnected then it is a relay or a solenoid. Theres no power going to the trim motor unless the relay or solenoid is engaged (closed). The problem is not with your trim motor unless a wire has worn through and is shorted to a hot lead somewhere.

Most boats have trim switches at the controls. I've had the trim switch in a control stick and cause a similar situation. Not sure what you have but I'd be checking switches first.

Click to expand...

If I recall correctly here is the chain of events.
I was making a crossing when I felt the trim go down. I noticed it would not trim up so I continued my passage. (note in the past I have had some shorts in the remote handle when activating the trim - blown fuses) but I think that problem was elliminated.

When I arrived at my destination beach I could hear that the electrical trim motor was still on even with engine off.

I disconnected the battery and had a beer to think.

Then I found 3 wires for the remote trim on the throttle and disconnectted them - reconnected battery and still motor stuck on. Reconnected trim wires.

Disconnected wires at the motor housing - still motor stuck on.

Disconnected trim cables at a connector in the motor - not sure which connector and this shut down the motor.

and so this is how I left it - with the trim motor off while I drove back home and used the engine over the weekend without trim.

Next week I will go back out and double check the trim switches again.

Will be interesting if I need to pull the boat out of the water. Now on a lift. It looks like I will have to use the manual release valve and raise by hand if i put on the trailer.

Thanks for your reply