1973 mercruiser 120 I/O power trim non operational

Jpcallahan

Cadet
Joined
Jul 26, 2013
Messages
7
Could use some help with diagnostics:
My power trim was working normally yesterday with the following exception: my upper trim limit is not connected, i use the top 2 buttons for up and the bottom button for in. Today, while raising the drive, the pitch and speedthe of the hydraulics seemed like my battery was dying. Hooked up the muffs and fired her up. This resulted in no change. After several attempts, the drive will not raise or lower. I get a solenoid click when attempting to raise and nothing when lowering. I removed the 3 prong connector and jumped between the red/green and red/blue with the same results. Electrically disconnected the hydraulic motor, applied a jumper directly from the black motor lead to negative terminal and jumped from positive terminal to blue and green motor leads respectively. This gave me no motor actuation at all. To me this indicates motor failure. Are there any other steps i can take to verify failure?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1973 mercruiser 120 I/O power trim non operational

Sounds like a motor fault to me too... The only other (unlikely) possibility is the hydraulic side of things is stalling the motor... I would start with the motor anyway. Open it up and check the brushes and the armature bushings/bearings... Any half reasonable auto-electrician should be able to fix it up for you if you can't/don't want to do the job yourself.... Brush kits are still available, as are the complete end plate (brushes and bushings included).

Chris......
 

Jpcallahan

Cadet
Joined
Jul 26, 2013
Messages
7
Re: 1973 mercruiser 120 I/O power trim non operational

Disassembled and found brushes gone, motor windings filthy, but sound. Cleaned and installed new brushes, stoned the commutator, cleaned and reassembled. Good to go. Thank you for the assist.
-Joe
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1973 mercruiser 120 I/O power trim non operational

Another happy customer... :D :D :D ;)
 
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