Only three wires in shifter

[mars bar]

I finally found a shifter assm. for my 1972 Johnson 50hp esl.The outer casing and wire harness looks the same but the one I replaced has 6 wires going to the shift switch and this one has only 3, blue and green are lower unit solenoid, purple with yellow strip I think is electric choke? Electric choke is not working. What are the functions of the two white wires in the old unit? Altogether there are 2 purple, 2 white, a green and a blue. I now have forward and reverse finally."Sober for over a week'!!! Thanks

 

[jonesg]

Re: Only three wires in shifter

I don't know, lets bump it back up...bump.

 

[freddyray21]

Re: Only three wires in shifter

the one you replaced more than likely had the key in the control box? for shifting there are only two wires used to shift. the blue and the green. You also need to make sure you have the right box. The older style electric shift boxes would have three wires coming out. blue, green and maybe purple I cannot remember. the blue and green go to the motor the third wire goes to the battery 12v +. Even on the newer ones there are still only three wires to shift. blue green and hot. However, the older boxes won't work on the newer hydro shifts and vice versa. Using them on the wrong lu will damage the lu and then you are talking real money.

 

[freddyray21]

Re: Only three wires in shifter

Hydro Electric Shift)
(J. Reeves)

The shifting setup of the lower unit is what's called a "Hydro Electric Shift", which is quite complex consisting of voltage being applied to solenoids in the lower unit which in turn change oil passages via a oil pump that supplies various pressure on a spring loaded shifter dog. The wires leading to the lower unit (at the powerhead) are "Green" and "Blue". The engine must be running or cranking over in order to shift out of forward gear.

You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Premium Blend" lube, commonly called "Type C". (A thinner lube)

In neutral, you need 12v to the "Green" wire.
In reverse, you need 12v to both wires, the "Green" one and the "Blue" one.
In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear)

To check the lower unit for proper shifting to make sure you have no trouble there, remove the spark plugs to avoid problems and to allow a higher cranking speed.

This next step eliminates the actual shift switch in case problems may exist there.... Disconnect the blue & green wires at the knife connectors (the rubber insulated boots) leading to the lower unit at the powerhead, then using jumpers, take voltage direct from the starter solenoid to apply voltage to the "Green" wire for neutral, then both wires 'Green" & "Blue" for reverse (Remember the engine must be cranking over in order to shift).
With no voltage applied, the unit should be in forward. No need for a ground jumper... the lower unit's already grounded. You may crank the engine with the key switch or by energizing the starter solenoid with a jumper wire.

The electric shifts which is the old style defaulted to neutral. 12v to green gave you one gear and 12v to the blue the other gear. 12v to both damages the lower unit so be careful.