throttle controller stuck in foreward

[trbarret]

hello, i am new to forum.

My name is terry and i recently , actually today had a problem with the throttle control on my 71 johnson 50 hp.

The throttle moves from foreward to neutral to reverse but only goes foreward, even in neutral.

I looked at inkage on motor it goes in the same directiion in neutral as it does in reverse.

The lower unit was recently changed by dealer, it worked this mornning then i had no reverse. I know the lower unit oil is correct because they told me it was thinner than the normal stuff.

So i checked for water in the lube , no water found.

What next? If anyone can help me isolate this i would surely appreciate it!

thanks

Terry

 

[Joe Reeves]

Re: throttle controller stuck in foreward

(Hydro Electric Shift System Explained)
(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)

Note: The engine must be running OR have the driveshaft turning by some other means in order for the engine to shift.

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.