1979 Mercury 80 HP power trim

[Kissdude]

I have a 1979, 80 HP Mercury with power trim and I was wondering if someone could please help me. The trim motor has a red, green, purple and blue wire. The motor lifts up and down but I can’t get it to go higher after it stops. My original control works by holding both up and out at the same time to get lift for trailer, mine will not lift any higher. Any info would be appreciated thanks.

 

[Chris1956]

The purple and blue wires are for the trim limit switch. Your original PTT panel had the three buttons. Maybe the top button is bad? They are good quality switches, but not indestructible. You can pull the rubber off the switch and see and maybe repair it. You will need a heavy-duty soldering iron, maybe 80W, some flux and rosin core solder.

Alternatively, you can use a single pole double throw switch, with the red wire on the center terminal, the green wire on the top terminal and the blue wire on the bottom terminal. You will need to connect the blue and purple wires together. Unplug them from the trim limit switch on the trim bracket and connect them with a short piece of wire and some bullet connectors.

 

[Kissdude]

I have replaced my controls with a quick silver lever that has trim up and down button. The up and down work but when I hook the blue and purple in the up position, nothing happens. You thinking maybe the limit switch is no good and why I should connect them together? I was trying to find the fuse for the purple wire,it’s at the pump?

 

[Chris1956]

I did not really understand your post. However, wiring for your PTT system is real simple without the trim limit switch.

The PTT pump/reservoir is connected by dedicated battery cables to the battery. The pump/reservoir body is connected to the ground cable, as is the black lead from the PTT motor.

The red cable to the PTT unit goes to one of the solenoids secondary (large) posts. If may go thru a circuit breaker or fuse. There is a jumper from it to the other solenoid's secondary winding (if you have one). Also run a wire from the red battery cable to the center connector of the switch.

Now install one wire from the top switch connector to the lower solenoid's primary (small) winding (if you have one) or directly to the motor's green wire.

Now install one wire from the switch lower connector to the upper solenoid's, primary (small) winding.

"Push the button, Max" and see what happens.

 

[Kissdude]

Alrighty then! Thanks for that. I will try and make clear what I have done. I took a motor off another boat to use on mine cause this motor has the PTT lift. As mentioned before, I changed the throttle controller to a quick silver one. I took the green wire and blue wire from that control and matched them on the green and blue from my pump. the motor goes up and down fine but when it reaches the stop in up position, I can't figure out how to get it any higher and I'm not even sure if it can go any higher. I thought when it said in trailer position, meant it was a lot higher. Thanks again.

 

[Chris1956]

Gee, jumper the up solenoid at the pump reservoir so it runs. See how high it goes. If not all the way up, something mechanical is amiss.

Watch those dog ear-shaped manual tilt locks as they can bind up the triple clamp.

Merc did make PTT units for lower HP motors, say the popular 50HP4cly. They looked a lot like the unit for the il4/6 motors that you have. Maybe you have a partially incompatible ptt unit? It is a guess.

 

[merc850]

This is the wiring diagram for the inside the boat pump

 

[Chris1956]

Merc850, I think he is well past the original wiring. He seems to have simplified it to a single switch and three wires.

If his motor doesn't trim all the way under PTT influence, I would think it mechanical, or some other issue.

 

[Kissdude]

I have the original pump and didn’t remove the rams. Motor goes all the way down and when I make it go up it rises. Gues I will have to measure the distance but it doesn’t go high enough to even engage the dog ear locks, stops about half way to engage those. Could it be low on oil maybe?

 

[Kissdude]

This is the wiring diagram for the inside the boat pump
View attachment 408300

This is the wiring diagram for the inside the boat pump
View attachment 408300

Exactly what I need... Thank you!

 

[Chris1956]

The trim rams should retract all the way into the trim cylinders, when the motor is full up. At that point, you should be able to lift the gearcase by hand to use the manual locks.

 

[Kissdude]

The trim rams should retract all the way into the trim cylinders, when the motor is full up. At that point, you should be able to lift the gearcase by hand to use the manual locks.

Oh I see, I thought it went all the way up on its own.. my bad! I guess it is working correctly. I just downloaded the actual manual for this PTT so I should be ok now. Thanks for the help!