XL175 Trim Runs Motor Up On It's Own

[Downrigger]

Went out ocean fishing the other day and all was good until the end of the day. Out of the blue the motor raised itself all the way up and the trim motor kept running. I had to switch off the batteries to stop it. Once it was switched back on I was able to lower the motor and continue only to have it do it again several times. You could stop the trim motor by pushing either the switch on the motor or on the throttle to "down" but it would keep running to raise if the switch was released. Pressing the switches to "down" only stopped the trim motor and didn't lower the motor.

A couple of times it would stop and you could lower the motor but it would eventually raise it again by itself. We eventually had to finally get it down and disconnect the relay to keep it down until we got it back to the dock.

I ordered new relays (since they get their 12V power from the switches I doubt they are the problem) and sprayed contact cleaner and then 2-26 into the switches after I got home. I checked all the wiring for frays or possible shorts. Before cleaning and lubricating the switches I ran the motor up and down at lease 15 times without being able to duplicate the problem. It seemed to only do it when the motor was running and I was on the water.

Any suggestions on what this could be? Swiches, relays, vibration closing the contacts on the relay, bad switch on the motor or throttle control.

This is on a 1992 Bayliner Trophy, 1997 XL175 Mercury outboard, trim switches on the motor and the throttle control.

Larry

 

[j_martin]

Re: XL175 Trim Runs Motor Up On It's Own

Any one of the trim switches could be the problem. Disconnected, there should be infinite resistance between any 2 terminals on each switch. The one that shows leakage is the culprit.

Could also be a frayed wire.

If it goes off on it's own, it's not likely a solenoid, or relay.

hope it helps
John

 

[Laddies]

Re: XL175 Trim Runs Motor Up On It's Own

9 times out of 10 it's the switch on the engine, just unplug it and see if problem goes away

 

[Downrigger]

Re: XL175 Trim Runs Motor Up On It's Own

9 times out of 10 it's the switch on the engine, just unplug it and see if problem goes away

Yup, replaced the up relay just to be sure, lubbed all the trim switches, took it out yesterday and about the end of the day up she goes on her own. I noticed that my swim platform directs salt water splash directly against the switch on the cowling while I'm underway so I decided to disconnect the hotwire on that switch and that solved the problem.

THANKS FOR THE HEADS-UP LADDIES!!!

Took a look at that switch and it's a real cheapy....not even water resistant let alone waterproof. What is Mercury thinking with that POS switch anyway? Not in the least applicable for salt water. If I replace it with a like switch this is just going to happen again real soon I think.

Does anyone know if they updated that switch with one more waterproof in later years. Heck, this one doesn't even has a rubber seal over the rocker.

 

[Jim13]

Re: XL175 Trim Runs Motor Up On It's Own

I had the same problem but it was the trim switch on my throttle control.

Glad you found it.

 

[Downrigger]

Re: XL175 Trim Runs Motor Up On It's Own

Local boat guru is telling me it will be a waste of time to replace the switch sinch the problem will just come back again. I'm sure he's right since my swim platform causes salt water to spray directly on the cheapo switch at certain speeds (exactly the speeds I go on the ocean). So, rather than have it start coming up when I can't hear it do so at cruising speeds and cause damage I'll just leave the hot wire unplugged and forget about it. Heck, I have to climb into the boat to start the engine to flush so it's not that important anyway.

Thanks for the replies,

Larry