Engine trimming itself up

[fishhawk5]

2021 Pro XS #3B045329 66.3 hrs 2021 Phoenix 921
This engine will randomly trim itself up when nobody is around. Sometimes you can listen closely and hear the throttle body cycling like it does when the ignition is turned on then off and not be moving the engine with the trim. You can also quickly bump the up button and sometimes make the throttle body cycle. When it has trimmed itself up, it completely drains the battery. Currently the work around is to unhook the battery. Bow and engine switches have been changed to no avail. Don't understand the connection with bumping the trim switch and getting the throttle body to cycle.

[Jasonrs]

The trim function "wakes " the engine if i remember correctly, not sure why its randomly going up tho...bad relay perhaps?

[EuropeanAM]

Isolate each trim switch, one at a time. If the cowling switch is determined to not be the cause, try disconnecting the 14 pin harness connector at the back of the engine, and see if the problem persists.

This will tell if the problem is something inside the cowling, OR something in the BOAT'S wiring.

Note: The PCM is forced to WAKE each time a trim signal is noted from a switch (engine and key OFF). This would be why you have the sounds of the ETC and relays cycling/clicking.

[fishhawk5]

That now makes more sense about why I am hearing the TB reset. I must be getting a very quick intermittent up signal from somewhere that will cycle the TB and not engage the trim. When the signal is longer the trim will move. Will take time to trace this since it is very random. Thank you for the responses, I will post the results.

[fly by night]

There could be a ghost lurking! LOL

[Arizona Angler]

it's the new technology, self trim for optimal fuel and speed efficiency.. pretty cool..huh

[EuropeanAM]

it's the new technology, self trim for optimal fuel and speed efficiency.. pretty cool..huh

Different feature, but it sure is!

[brinson]

Fishhawk, I have a Verado but mine was doing something similar and was randomly trimming up when running. I traced my problem to wiring on the cowling trim switch had rubbed on the engine and was going to ground.

[rpr]

I had the same thing on my Verado. Scary. The cowling switch was replaced and it hasn’t done it since, but Ive barely used the boat since and I still don’t completely trust it. There was no visible damage to the switch or the wiring.