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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14165
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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Help, My 50HP outboard 4 stroke power trim keeps putting itself

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Help, My 50HP outboard 4 stroke power trim keeps putting itself in the up position and I have replaced the relays and the switch on the control lever has been checked it is OK could this be a bad selinoid or the up/down switch on the motor itself? anyone know or do I have a short somewhere?

Hello, and welcome to Justanswer. My name is XXXXX XXXXX I will be helping you today. If you need clarification on something please post back here.


Does this happen only when the boat is running. Or when you just have it sitting there on the trailer unattended?


If the motor starts to trim up by iteself, how do you stop it? Does hitting the buttons work or do you have to disconnect the battery?

Customer: replied 5 years ago.
It goes in the up position unattended and I have to disconnect the battery to stop it



Then you have a short circuit that is sending power down through the blue wire someplace. The trim pump uses 2 wires, a blue and a green. If you put power to blue, the motor goes up, power to green, and it goes down.


Shorts will either stand right out, or can be extremely extremely hard to find, and you can spend all day on it. But 9 times out of 10 where the problem is, is a bad switch in the remote control handle that is putting power to the blue wire. Or, in the remote control, where the trim wires run down through the handle.


What I would start with first is popping the handle off and inspecting the wires for the trim where they run into the handle, and and to the control box. It is usually right there in that point, where it leaves the handle and goes into the box that they chaffe and the red wire puts power to the blue wire.

There is a grommet in there that is supposed to keep that from happening, but the grommet likes to fall out over time.


I would start by looking for shorts in that area first.

Like I said before, its either going to be real easy to find, and the short is right were I said it would be. Or its not, and you can spend all day looking for it.


Post back with questions.
good luck!




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Customer: replied 5 years ago.

Have already checked the up down buttons on the throttle handle is it possible the swith in powertrim swith in the lower unit of the motor is shorting It is a 2008 motor but it did get wet with the top off could the water cause this

I know I am confusing so I will start again the up down switch in the throttle handle checks out the relays are fine apparently a selinoid would not be the answer and the Power trim motor works so it is getting stuck in the up position and continually runs until power supply is cut off. There is a second power trim up and down switch in the lower unit of the motor could this switch be bad or short circuiting from getting wet?

Thats the problem with shorts like this, they can be hard or easy to find. Normally its right there in the handle, where the wires run down through it. But it can also be anyplace at all on the motor. Every inch of wiring from the button on the throttle handle down to the motor itself needs to be gone through if you can't find the short easily.


Try this. Make sure the battery is on. You can leave the engine off. Go and jiggle the remote conrol handle, put the throttle into "throttle only mode", and swing it foward and back a few times, see if doing that makes the trim motor react in any way.

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