1983 Mercury 80hp trim tilt problem

sail51

Cadet
Joined
Dec 12, 2009
Messages
9
I am trying to trouble shoot the tilt/trim system on this mid 80's Mercury O/B. My engine will go all the way down and then trim up to the point where you would need the trailer button. I can hotwire across the trim/tilt solenoids and I can make the engine go up and down without a problem. I removed the trailer button and the toggle switch so I have the 4 wires exposed that feed the switches. I thought this would tell me if the problem was in one of these switches but it does the same thing (down and then up slightly and then it stops moving). Once it stops on this upward part of the cycle I can get it to work again if I use a wire to go across the solenoids for 1-2 seconds then trim tilt will begin to operate properly again from the toggle/trailer switch as long as I don't go back down and try to go up then it stops.

I measured the voltage at the tilt/trim controls and I get 12 volts at the blue (up) or green (down) wire, but when I go through the cycle and when it stops on the way up I have 3 volts at those same leads. Once I do a quick solenoid hot wire across 12 volts again.

I tried disconnecting the trim tilt switch wire that is at the hydraulic cylinders at the transom and the same thing happens.

Very frustrated
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
You have the two trim cylinder. pump+reservoir in boat system, right? If so, if you connect a jumper wire across the trim limit switch bullet connectors on the PTT harness (These connectors are wired to the starboard PTT cylinder bracket) the trim button will allow trim as well as tilt.
 

sail51

Cadet
Joined
Dec 12, 2009
Messages
9
Didn't work, but I think it maybe a loose connection somewhere. When the engine tilts up about 10-15 degrees (same point all the time) it always stops, but if i wait a few minutes it will work again. If I instead give the engine a little shake it will also work right away. Now to find that loose connection....
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
Remove all electrical connectors, give them a hard tug to see if the wire breaks off, if not , then clean them bright shinny.
Then check every inch of wire for a break or short, grounded out.
Your sure T&T fluid.is full.
Do you have a factory service manual ? If not you-tube may have the answers.
 
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