SOS Wiring Diagram

Seems like John in la has been very helpful in providing wiring diagrams for many of the old Fords. It seems like the diagrams don't exist in the forum archives. I have the 881-D and would like a diagram that includes the Park safety switch, Trans pressure switch, lights on the dash and selector assembly, manifold heaters, etc.

Thanks, Rick

I'm not sure about those earlier 4 cylinder models, but the I&T FO-31 has the full wiring diagram for the 1965-1965 tractors, including the differences between the diesel and gasoline models and the additional wiring for the S-O-S in an inset box down in the corner. There's actually two different diagrams in there, one for the US ("C" s/n prefix) tractors and the other for the European ("A" and "B" s/n prefix) tractors.

The Park safety switch on the S-O-S should be wired exactly the same as the neutral safety switch in the manual trans models, it's just the mechanical interconnect to the transmission that's different and makes it only start in Park vs. neutral on the others.

Thanks Sean, I don't have an FO-31 cause all of mine are red and/or grey. I think I worked my way through it this weekend. What confused the heck out of me was the Park Safety Switch. I spent a lot of time reviewing the procedure to R&R the shifter assembly and noticed a procedure to disconnect the safety switch wire when removing the assembly. My assembly had a micro-switch installed on the shifter body that i guess indicated "Park" on the flat side of the shaft. I remember thinking I can't imagine that they had micro-switches in the late 50s. I didn't spend time in the manual regarding the cover removal but I did this weekend and removed the cover and found the real Park Safety Switch, that worked after I adjusted its position against the cam. Now it all makes sense to me. I did find a 2011 archive post where Larry NCKS posted a written description of the wiring differences between the SOS and standard trannys. That post indicated that not only is the Park Safety switch go to ground but so does the transmission pressure switch and assembly bulb. I never got an answer to the question, "How to tell when the shifter is in Park when the assembly has been removed and the gears were changed without the shifter assembly", but the easy answer would be that the wire coming out of the cover should have continuity to ground when in Park.

I'm going to draw up the SOS wiring diagram with included manifold heater, Park safety, assembly light, pressure switch, etc. wiring and see if I can get it reviewed here.

Sean do you know why the archive posts don't show photos anymore? I'm guessing they want the space on the server. Rick

I think that most pictures in posts are actually stored in other places, like the photbucket album of the person that posted it, and all that's in the post itself is the URL to the photo that is elsewhere, and over time people rearrange their photobucket albums and the old URL becomes orphaned.

I'd rather hit my big toe with a ball peen hammer then work on those SOS tranny's

dave in mich

(quoted from post at 08:45:31 06/01/15) I'd rather hit my big toe with a ball peen hammer then work on those SOS tranny's

dave in mich

Click to expand...

I'll buy you the ball peen hammer, if you'll let me do the hitting! :lol:

NT