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Neutral Safety Switch 1977 OMC

A

Alan S

Contributing Member
1977 Century. I had lower unit apart for years and got it back together. Engine will not crank. I held the ignition key on crank and when I moved the throttle back and forth I found a position that made the engine crank as I was moving by it. I must have moved the position on the neutral position at some point it has been setting for years so I don't remember. Any advice? I am thinking I will try to disassemble and see if I can figure out how to adjust it.
 
You say had lower unit apart so I assume we are talking about an electric shift I/O.
There is no neutral adjustment, there is no shift cable on an electric shift. It all happens in the control box. I'd assume the switch contacts are dirty/corroded from sitting unused.
Now, if you have a mechanical shift lower unit then you have a 78 model year drive.
 
Droid said:
You say had lower unit apart so I assume we are talking about an electric shift I/O.
There is no neutral adjustment, there is no shift cable on an electric shift. It all happens in the control box. I'd assume the switch contacts are dirty/corroded from sitting unused.
Now, if you have a mechanical shift lower unit then you have a 78 model year drive.
Click to expand...
Yes it had electric wires down inside the lower unit on the I/O. I got the shifter off but I was not able to reproduce the cranking of the engine by moving any thing. I see two prongs for the switch that have no wires to them. I kind of remember a guy that worked on it saying something about bypassing my switch is this possibly why there are no wires on the prongs? I will try to send you a picture.
On another note do you think the ignition switch itself might be the problem and working intermittently? I will try to bypass that.
 
Droid said:
You say had lower unit apart so I assume we are talking about an electric shift I/O.
There is no neutral adjustment, there is no shift cable on an electric shift. It all happens in the control box. I'd assume the switch contacts are dirty/corroded from sitting unused.
Now, if you have a mechanical shift lower unit then you have a 78 model year drive.
Click to expand...
 

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You are looking for yellow with a red tracer wire from key switch to that bypassed switch then back to I believe a solenoid mounted on a triangular plate. (Yellow with red is current color, I don't know if OMC used that color coding back then).
Regardless, see if you have 12 volts at the solenoid end of the wire when turning the key.
Does the solenoid clunk but engine not crank? If so, solenoid us faulty.
Item #35.
Look for 12volts at wire 34 (I think, see below) with key turned to start. If not, apply 12 volts there with a jumper lead.
About wire 34.....
One small stud on solenoid gets power from key switch, the other should go to ground. Look for the yellow/red wire: this is the one I believe to be #34. The other should be black to ground. Regardless, those 2 small studs need 12v pos & the other 12v neg.
Technically it doesn't matter which is which.
 
Last edited:
Droid said:
You say had lower unit apart so I assume we are talking about an electric shift I/O.
There is no neutral adjustment, there is no shift cable on an electric shift. It all happens in the control box. I'd assume the switch contacts are dirty/corroded from sitting unused.
Now, if you have a mechanical shift lower unit then you have a 78 model year drive.
Click to expand...

Droid said:
View attachment 36829
Click to expand...
I checked the wires 33 and 34. The hot wire had no juice. We jumped it and it cranked right away. I ran a complete new wire from the ignition start switch and it cranks fine. Thank you for your guidance.
However, now I can't seem to get it in neutral the prop spins either in forward or reverse. I did not mount the throttle lever on the side wall yet, in case I need to wire it somehow. Should this go through the neutral safety switch some how? Also should I have a fuse in line? I think there is one coming into the ignition already.
 
32 should be a fuse going to the dash harness. The switch (2 unused spade terminals) in your picture is the neutral safety switch (NSS). You can put an ohm meter across it & check for continuity. If it works, I'd reconnect it for safety. No fuse in the start circuit.
Again, there is no adjustment for shifting. There is a 2nd switch in that controller. Has Red, Blue & Green wires if I remember correctly.
Red is hot with key on & should pass 12volts to green & blue as you select gears. Neither blue or green get power in neutral.

Clarify this your above post....
"However, now I can't seem to get it in neutral the prop spins either in forward or reverse"

Are you saying you are running it on the trailer with a flushing adapter & the prop turns slowly? Not unusual & try to stop prop with a stick. It should stop. Caused by oil circulation & drag.

With key on, engine off & shifter in neutral, prop should spin by hand easily.
Shift into forward (key on, eng still off) & prop will turn by hand with drag one way & turn a bit the other way then lock. Select reverse & see if prop does the opposite. If prop reacts as I just described, it's good to go.
 
I'm a bit confused with your pictures as I think that is the NSS yet there are 5 wires coming from the shift switch.
I'm thinking Teleflex made those controllers for OMC. Since that is electric shift maybe that switch isn't used because there is no shift mechanism. I'm pretty certain it all goes thru the big switch with 5 wires. Ohm the white to white (or gray to gray, I can't tell). Does that work as a NSS? On the older OMC control that is visible on the wall, it is also the NSS. Very early like pre '68 did not incorporate a NSS at all, only had 3 wires.
 
Ok. I did not tell you I found the yellow wire with the red tracer it was cut under the dash and I did not see any more of it.
I checked the continuity of the NSS and after working it a few times it is good.
So I should run the ignition start wire to one side of the NSS and then out the other side and back to the solenoid?
I did not start the engine, I just gave it a quick crank I don't have fuel in it yet. But when I crank it the prop would go one way or the other depending on the throttle position. I could not seem to find neutral with the switch not mounted. I think there is a lot of play in the switch. I will mount it and see if this helps or do you think I should take it apart and look inside it for loose parts?
 
Droid said:
I'm a bit confused with your pictures as I think that is the NSS yet there are 5 wires coming from the shift switch.
I'm thinking Teleflex made those controllers for OMC. Since that is electric shift maybe that switch isn't used because there is no shift mechanism. I'm pretty certain it all goes thru the big switch with 5 wires. Ohm the white to white (or gray to gray, I can't tell). Does that work as a NSS? On the older OMC control that is visible on the wall, it is also the NSS. Very early like pre '68 did not incorporate a NSS at all, only had 3 wires.
Click to expand...
Sorry I just saw this post. Those 5 wires must have done something to keep it from starting in gear. How do I OHM the white wires, should I scrape some of the insulation off? or take the switch apart?
Also I will try the shifter test tomorrow. Sorry if I am keeping you awake. Have a good evening,
Alan
 
I'm always up at this time.

Do the 2 white wires connect to anything from the switch? Do they go to the 5 pin plug into the boat wire harness? If yes, where do they end up? Ohm them there or where ever you have access. Do they show circuit closed in neutral & open in gear?
Does the switch in your picture show open & closed also?

Regarding the yellow/red, that is the best to use so future people know what is going on. But it needs to be special ordered, it's not an off the shelf item. I have a roll of 16ga for my projects. If nothing else, use plain yellow. Bottom line is starter solenoid power comes off "S" terminal & goes to solenoid preferably using a NSS.
 
Like I said above, I think Teleflex made the controller for OMC but maybe I'm wrong. IDK If you have an OMC or Telefex or maybe Morse. TBH, I'm not sure if aftermarket was available but I think yes.
Please post the outcome.
 
I played around with the switch and it is hard to tell when it is in neutral but when it was there the engine cranked every time. If I put it in gear it would give some resistance to the prop turning. In Neutral the prop turned freely.
I put the throttle back in the side wall and it doesn't seem to move in and out of gear properly, and it won't crank. I think something is loose inside the switch. I am going to try to take the switch apart. I found a part number it is M-1093-D2.
Also just to let you know I found the plug up under the dash but at that point I could not get the switch in neutral to test OHM. It would have continuity between the red and the blue or red and green though, I guess because it was in gear.
 
Yes, red is 12volts from key switch & it goes to blue or green depending on which gear is selected. Or goes nowhere in neutral.
 
I found one problem, there is a spring with a ball bearing hold it in. The allen screw that holds in tight is missing. Not sure if this is the problem yet but will find one and put it back together. Every thing else looks solid just dirty grease I cleaned up. My computer is giving me trouble sending a picture I will let you know how it goes. Thank you for all your help.
 
Droid, I took the shifter box apart cleaned the old grease, regreased it all got a new allen screw for the ball bearing and everything worked alot better it shifted normal again. But, I still had no power no continuity at the white wires.
I pulled the plunger on that switch out and put it in the neutral position still nothing. So I took the tube on that switch apart and bent the contacts in a little. I put the plunger in neutral position and I now had continuity. I put it all back together and it now works. Cranks in neutral not in gear and prop engages when in gear. Thank you very much for walking me through this, and have a great Easter!
 
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