I am pulling a 1990 johnson 70 off my boat, and putting a 1979 johnson 100 on. The controls are set up for a two wire tilt & trim system, and the 79, 100 has a three wire system, what do I need to do to make the three wire system work?
You should be able to use what you have for controls. I don't know for sure but it seems like you should be able to use two relays to do what you need. One wire on the T&T should be a feed (either ground or power) and the other two will be for the up and down directions. The relays will need to be DPDT, so when they aren't energized the circuit is open. One wire from your switch will goto one relay, andt he other wire the other relay. When the switch is pushed in either the up or down, it will trigger the appropriate relay to close either the up or down part of the circuit. It's tough to explain a circuit so here's a link to a quick diagram that I hope helps:<br /><br /> http://www.design-cycle.com/two_wire_diagram.jpg <br /><br />Notice no connection on 87a of the relay (that's the normally close position. Also this assumes the feed wire to the pump is ground and the other two wires get power for operation, this may need to be switched (try with just a battery before hand). Hope this helps!
I not totally positive, but I think you could just swap the T & T units between the 2 motors. Otherwise, on the 3 wire unit, the black wire goes to ground and you would alternatively connect either the blue or green wire to battery positive to go up or down. This is quite different from the 2 wire setup where there is no separate ground wire and the blue and green wires are swapped between the battery positive and negative terminals for up and down.
If the old 3 wire system is complete then youre good to go. The switch in the control box doesnt know or care which system you use. <br /><br />The 2 wire motor uses 2 relays and the 3 wire motor uses a solenoid for up (blue) and a direct connection for down (green).
I guess I never thought of it before, but what Dhadley says is right (of course). If you just connect the blue and green wires on the new unit to where they were connected on the previous one and connect the black wire to ground it should work just fine.
Are the switches for the 2 wire the same as a three wire? They may look the same but are they both rated for high current? The direct connection on the down can draw as much as 30amps and if that switch isn't rated for that kind of current draw then it'll get messed up and un-useable.<br /><br />The diagram is labelled as a two wire but I modified it for a three wire system. Should work the way it is and take all current strain off the switch as the relays do all the work.
SC -- you can do exactly as your diagram says. You removed the wire that "communicates" between the two relays used on the 2 wire motor. That allows you to use a 3 wire motor with the relay set up.
Thank you for confirming for me, don't want to be leaving anything that isn't going to work in this post. I am wondering about those switches for the T&T though. Are they all rated for 30 amps? If they are I can think of a million and one other applications I could use one in where I want a switch just like that
