No reverse

76powercat

Recruit
Joined
Feb 21, 2004
Messages
4
I have a 1970 Johnson 115hp that will go fine in forward but does not have neutral or reverse. The funny thing is, when you pull the stick back to go in reverse, the motor goes forward? I opened the throttle box and there is an eletrical scitch that has all the wires cut going to it (would this have any effect on the reverse?). I should let you know that the key switch is aftermarket and is no longer in the throttle box. Does anyone have an idea on what could be wrong or any diagrams of the throttle linkage at the motor? Thanks for your help in advance.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: No reverse

(Hydro Electric Shift)<br />(J. Reeves)<br /><br />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.<br /> <br />You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Preminum Blend" lube, commonly called "Type C". (A thinner lube) <br /><br />In neutral, you need 12v to the "Green" wire. <br />In reverse, you need 12v to both wires, the "Green" one and the "Blue" one. <br />In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear) <br /><br />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. <br /><br />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).<br /> <br />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.
 

76powercat

Recruit
Joined
Feb 21, 2004
Messages
4
Re: No reverse

Joe, <br />Thanks so much, that gave me a very good place to start. So, if I check the voltage and the motor will go into neutral and reverse when I hook up a jumper wire, could the problem be in the electrical switch in the throttle box (by the driver seat). Like I said, this looks as if all the wires have been cut going to it. Is there any where to get a wiring diagram for this switch or would that only be in a service book.
 
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