I'm replacing my trim pump set up on my 95 272 baja. I don't want to buy the wrong set up, so my question is how do you tell if you need the 2 wire or 3 wire set up?
Does it go my the # of wires coming out the pump motor itself, or do you go by the control connector which plugs to the relays? Thanks Robert

If your pump has 3 wires coming out of it (black, blue, green), then you need a 3 wire pump.
Eddie

Two wire or three is referring to the wires coming out of motor .On two wire ,up or down is done by swapping polarity. On three wire the ground is third wire and you apply power to either of the other two for up or down .....Blue is up ,green is down .
A 95 merc pump is a three wire

You guys are great. Thank you.

So is it true that if you were rigged for 2 wire and changed to a 3 wire motor/pump you could simply eliminate the blk wire and use the green and blue to reverse polarity?

on a 3 wire pump,nothing will happen unless the black+1 of the other color wires are used.

doh! I just got a 3 wire and suspect my old junk is 2 wire, not uncovered yet so too soon to tell for sure... thanks for the insight.

I didnt know there were 3 wire motors but it seems that if you wanted to use a 3 instead of a 2, all you would have to do is change the relay wiring to make them normal switches instead of polarity reversing.

Have a look at a 3 wire schematic and compare it to the 2 wire.

i think that would work.

I agree too. It should not be a problem to figure out.