1979 2.0 L Mercury v175 trim running in wrong direction

bassin89

Seaman
Joined
Dec 19, 2011
Messages
65
My 1979 mercury v175 has recently developed an issue where the motor is intermittently going up when i hit the down switch. Sometimes it will start going up then make a sound like it is in a bind and start going down as it should. Has anyone else had this problem? What could make the trim intermittently run in the wrong direction? Fyi, this model has the seperate trim motor unit mounted inside the boat.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Gee, the only thing I can think of is a faulty trim (up) solenoid or a faulty trim up switch, although, it is a wild guess.

I am guessing you are getting voltage on the down and up circuit at the same time.....

For test purposes, you can wire the switch directly to the motor, and bypass the up solenoid. That will eliminate that issue.
 

Kronos

Seaman Apprentice
Joined
Nov 20, 2017
Messages
35
You should be able to measure voltage on the up and then on thr down wire while pressing the buttons - to see if you have voltage on both.

Or maybe measure on the trim switch? See which circuit is open and not while pressing.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Faulty reverse lock valve or sticky reverse interlock micro switch.....the motor is running down just fluid sent wrong direction for a few seconds. Trim motor wont run if both up/down solenoid gets engaged..likely to short armature if this happened.
 

bassin89

Seaman
Joined
Dec 19, 2011
Messages
65
Faztbullet, that sounds like exactly what it is doing. How difficult of a fix is this?
 
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