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1978 80hp Mercury power trim problems

S

surgemc

Member
G'day everyone, we have a project boat going at the moment and are having a few problems with the power trim and tilt which was disconnected when we got it. The motor operates when we push the down button on the control box but nothing happens when we push either the up button or the trailer button. It has 3 wires coming from the control box which then go into a 2 pin plug. The wires appear to be blue, purple and green and the blue and green have been joined together before the plug.
My questions are:
1. Have the wires been joined correctly?
2. What tests can I do to trace the problem?
3. Does the position of the reverse lock knob have any affect on the operation?
Thanks in anticipation
Brett
 
Blue is the up wire,green is the down and the purple will be the power.So if both green and blue wires are wired together something is not going to work.Get youself two solenoid relays and wire the wires seperate.
 
There should be purple/white stripe wire and a blue/white stripe wire,somewhere,with bullet connectors.the purple wire connects these two together for the trailering switch.
I have just re-read your post.
The above is the way it should be,but to see if it is working try splitting the blue and green,join the purple and blue instead and give it another go.
 
I also made the assumption the you have the tilt trim with the two rams on the side of the saddle and the pump in the boat.'Cause you mention reverse lock knob,which prevents the outboard climbing out of the water in reverse when engaged.And as they say,whoever "they"are,a picture paints a thousand words.
Pic1 Two ram trim I think you have.My beautiful '69Merc800 with two ram tilt, which will be transfered to the boat in pic3.......sometime
Pic2 Wiring used with three button switch.Join or put a jumper here.
Pic3 Three button switch,hard to see
Pic4 Wiring from trim switch on remote control.The other two wires are from the trim limit switch on the bracket.Join or jumper
Pic5 Remote control and trim switch in lever.This is the control that I use at the moment on my '69 Merc800.
Pic6 Better pic of three button switch
 

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I have discovered that the up solenoid is faulty so I will have to replace that. Not sure if the buttons on the control box are faulty as well because I tried a continuity test test on them and got no result which I don't understand as I know the down button was definitely working. Any ideas? My control appears identical to yours except my stripe is blue. I don't have the separate 3 button switch that you do. I am having no luck at getting pictures onto here, but the pump actually has 3 connections on it even though the plug only has 2.
 
A quick test,you'll need a third hand,set meter on ohm,put one lead on the up wire,blue,and the other lead on the red and get someone to press the up button.You should get continuity and repeat the process with the red wire and the green pressing the down button,again continuity.No continuity means there is a problem somewhere.Ignition switch in the on position for the test.
There should be a three pin plug on the end of the wire as in pic two and a similar socket on the pump.If not we'll work out how it's wired.Could you podt a pic of the pump connection?
 
I've given up on trying to put pic's on here. I can't fully understand the instructions and have had no response from contacting the help desk. At this stage I have managed to get the down button on the throttle handle to work and the trailer button makes the motor go up, so I'll leave it at that for the moment as I'm now trying to work out how to test the switch box as I think it is faulty and the cause of no spark in cylinders 3 & 4. I will get back to the throttle handle switch at some point as it would be much more convenient to have both buttons working.BTW I needed to replace both solenoids as one was faulty and the other disintegrated when I was connecting the new wires. Thanks for your help, much appreciated.
 
I should have mentioned that I tried the continuity test with a normal Multimeter and got no result on any buttons however a friend who is an electrician used some powerful meter he has that put 240v through the switch and discovered that there was very high resistance on all 3 buttons, very confusing. I also tried to wire the pump directly to a rocker switch (ie bypassing the trailer switch) but as soon as I connected more than one wire, even though the switch was in the off position, the motor would start running. This has obviously got something to do with the wiring between the 2 solenoids to accommodate the trailer switch.
 
I have nowbought 2 new solenoids and replaced all the wiring on the pump. I haveseparated the Purple, Blue and green wires and run them directly to thesolenoid. I can now get the pump to run down by pushing the down button on thethrottle handle and up by pushing the Trailer button on the control box. The UPbutton still doesn't wor k. The wires shown in the pics are obviouslythe trim limit switch which is no longer connected. I have read on other postshere that when the limit switch is not working that stops the UP button fromworking however I haven't seen a solution to this anywhere. Ideally I don'twant to attempt to replace the limit switch so can these wires be bypassed andif so how.
 
Pic 4 in post #5.Pull the two wires fro the limit switch and put in a jumper along the white line from the two blue to the purple.When my trim limit switch goes that is what I will do.And me after melting my brain to get it working in the first place.:)
 
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