Motor trim by itself

[Justbass11]

So I come home from work this morning and my motor was trimmed up with the sound of the trim going off. Tried to trim it back down but no luck, then it stopped but couldn't trim it back down. Then it the sound came back on and stopped after a few seconds. Anyone ever heard of this before??? Now I can't get it to trim back down, again has anyone heard of that happening??? Any help would be greatly appreciated.

[jbh3]

Probably a short due to moisture in one of the switches. Most likely the one at the bow, if you have one, or on the engine cowl. Disconnect one at a time and see if you have trim/tilt at the other station(s). If no luck, you'll need to disconnect the battery to keep from burning the trim motor up, and lower the engine manually.

[Fishing Rhino]

Rain.  It has happened to me, once, and no more.  I had the same experience after a torrential downpour.  I disconnected the battery, bought a switch and installed it.

I had visions of it occurring when I was traveling down the highway.  The motor would tilt up.  The front of the transom saver would drop.  And instant polevault of the lower unit.  The least that would happen is that the transom saver would become junk.  The worst?  The lower unit could become junk.

Having a battery switch in the off position eliminates a lot of potential problems.  The first thing I do after installing the transom saver is to turn the switch off.  It prevents anyone from playing with all the electrical switches except for the trolling motor.  I unplug that as part of the process of loading the boat onto the trailer.

[Further North]

I saw this same thing on another forum somewhere, just in the past few months...and I'm sorry, but I can't remember where.

I do recall that is was a short of some kind.

[Justbass11]

Thanks guys and Fishing Rhino it we had a tornado watch with major rain last night. Thanks again but its off to work a 16 hr day

[Kevin22]

Had that happen to someone at a fishing resort I was at a few years ago. After a big rain his motor would go up then pause for a few seconds and start going back up again. He had a hell of a time getting it back on the trailer, It was the one on the motor so he had to haul the boat to a local shop and get it fixed so he could fish the rest of the week. They gouged him something awful, as you can imagine. Was something like $800 to replace the switch. 

[Way2slow]

As other have mentioned, most likely a trim switch got water in it but as for any help beyond that, my crystal ball wouldn't work, "my motor" is too broad of a term for it.

[Fishing Rhino]

It's going to be the trim switch on the bow.  The trim control on the throttle lever  and the one on the motor are vertical in their configuration.  The horizontal switch at the bow can accumulate enough water to create a short that will activate the tilt motor.

[Justbass11]

03 150 Mercury 

[noway]

Mine was a defective trim switch at the throttle.  Not a water issue.

[BassnChris]

On April 2, 2016 at 8:21 AM, Fishing Rhino said:

Rain.  It has happened to me, once, and no more.  I had the same experience after a torrential downpour.  I disconnected the battery, bought a switch and installed it.

I had visions of it occurring when I was traveling down the highway.  The motor would tilt up.  The front of the transom saver would drop.  And instant polevault of the lower unit.  The least that would happen is that the transom saver would become junk.  The worst?  The lower unit could become junk.

Having a battery switch in the off position eliminates a lot of potential problems.  The first thing I do after installing the transom saver is to turn the switch off.  It prevents anyone from playing with all the electrical switches except for the trolling motor.  I unplug that as part of the process of loading the boat onto the trailer.

I read this in Tom's original post about his experience.

i promptly installed a switch after that.

[WIGuide]

Had this happen to me during a tournament. The boat I bought had the trim button replaced (by a marina) The morons didn't use a waterproof switch. I didn't think anything of it and had fished in heavy rain with it a few times without issue. During this one tournament though it was on a chain of lakes that the lakes were pretty much like big bowls and was super windy. Fishing all day you'd take some waves rolling over the bow and soak everything. With about an hour left in the first day I could hear my trim running. I couldn't get it to stop, so I opened up the cover and pulled the relay. When we got back to the landing I put it back in and it had stopped. Same thing happened on the second day. I had put 2 and 2 together by then and pulled the leads on the front switch and it worked. Later replaced the switch with a waterproof one and haven't had a problem since. 

[Justbass11]

I found out what was wrong, My buddy from work dad who has been working on boats for a long time. He found that the trim relays were the problem on the motor. Also fried the one battery with I am getting today. Thanks for all the insight and help.