1979 mercury 80 thunderbolt power trim help

BP1969

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Just bought a boat with mercury 80 thunderbolt with power trim. Just started to try to figure out why it's not working. My unit has three buttons for trim. Can someone help me out on what they do. Bottom button says in and the next to buttons say up. Any info would be great. Thanks
 

BP1969

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Sorry the lower button says in the next button up says out and up and the next button say up.
 

GA_Boater

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Howdy, BP.

The IN button lowers the drive, the Out button lifts the drive to the trim limit and two UP buttons are held together to tilt the drive all the way up. That's why the center button is labeled Out for trim out and UP for tilt up.


upout.png
 

Chris1956

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BTW - the trim limit switches tended to break. You may find that the middle button by itself does nothing.

If so, you can bypass the trim limit switch easily.
 

BP1969

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Upon a brief check that seems to be exactly what's going on. How can I bypass this?
Thank you.
 

GA_Boater

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Just what is it doing or not doing? Any trim movement at all?
 

BP1969

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Just starting to get into as time allows but the in button makes a clicking noise like it wants to do something no noise from the out button but I do get a noise from the out and up button together. Then noticed it doesn't have oil or much oil so next step is to fill her up below the screw them I assume bleed the lines with the vent screw to get all the air out then go from there. Thanks
 

Chris1956

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If the trim motor doesn't run, it needs to be troubleshot. That motor has the trim motor and reservoir in the boat, right?
 

Chris1956

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OK, make sure the solenoids are providing power to the green or blue wires on the motor, when the trim buttons are pushed. Make sure motor's black wire is well grounded.

It makes sense to jumper from battery to green and blue wires on motor, in turn and see if motor spins. If she no spin, and ground is good, you could have a bad motor.
 

BP1969

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Thank you for all your help. Winter has settled in where I live in the mountains of colorado so she's covered up for a while. I was also able to fire it up after the previous owner let it sit for three years. Gas was bad some fuel line where cracked but I was able to get her going enough to winterize it. One thing that didn't see happen was I didn't see any coolant water coming out the unit. I should be able to drop the lower unit and at least get that in the garage and see whats up with the pump or impeller. Did notice that I think seloc has a repair manual for that motor and hopefully trim. Do you recommend that or is a better manual out there?
thanks again.
 

Chris1956

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Seloc and Clymer service manuals tend to have large errors about important items in them. I therefore recommend a Mercury Service manual.
 

BP1969

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(If so, you can bypass the trim limit switch easily). What's the method to do so. Thank you.
 

Chris1956

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If you trace the wiring harness for the PTT unit, you will see two wires that run to the starboard power trim bracket. Internal to that trim bracket is the trim limit switch. Simply unplug the wires to the trim limit switch and connect the harness wires together. You may need to make a jumper out of bullet connectors, as I don't remember the gender of the switch wires.

However, it the trim motor doesn't run in the down direction or doesn't run up, when both top and middle buttons are pressed, you have other issues.
 
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