PTO Wiring gone bad

[Brad520H 17]

hi there I’m completely new to both this website and to wheelhorse tractors. Was given a 520H (unsure of year) and started cleaning band trying to restore. While doing so I came across the switch for the PTO with all wires broken off. Any ideas how to just replace the switch?

[Achto 29,058]

 

You could put new terminals on the wires and install them back into the plug.

 

Check out our manuals section to get a wire diagram.

[Handy Don 13,507]

Welcome to the forum.

Glad to see you are trying to keep this tractor alive!

 

If you can get the model number off the tag on the fender next to the seat, we can help you find the diagram.

 

There should be two switches there, “stacked” side by side. One prevents starting the engine with the PTO engaged and one shuts off the engine if the operator gets off the seat while the PTO is engaged.

 

 

I can see the stubs of the purple, green, and brown wires sticking out of the plug that connect with the bundle at the top of the picture.

 

Some other hints while you are at this on a 40 year old machine that may have been through many hands and not always treated well.

- I can see a lot of rust around the black wires bolted to the frame. These are grounds and it’d be good to remove, clean, and reinstall to make sure they are making good electrical contact. Same goes for any other grounds.

- On the visible switch, the leftmost terminal (with the green stub of wire protruding) has a scorch mark adjacent to the switch body “NO3” label. That indicates heating from a poor connection inside the plug at the terminal on the switch--that’ll need cleaning as well.

- Do not totally rely absolutely on the color coding of the wires as seen in the wiring diagrams--double check by tracing the wires per the diagram. Even if a previous owner has not altered things, the factory was not always consistent!

- Its not at all uncommon to find that previous owners have tried to “improve” the wiring to suit their own desires. If you can, putting things back to original configurations is the safest.

[rjg854 11,967]

Some good starting points have been made already. Good luck with your repair.

[Brad520H 17]

1 hour ago, Achto said:

 

You could put new terminals on the wires and install them back into the plug.

 

Check out our manuals section to get a wire diagram.

Thank you!

[Brad520H 17]

1 hour ago, Handy Don said:

Welcome to the forum.

Glad to see you are trying to keep this tractor alive!

 

If you can get the model number off the tag on the fender next to the seat, we can help you find the diagram.

 

There should be two switches there, “stacked” side by side. One prevents starting the engine with the PTO engaged and one shuts off the engine if the operator gets off the seat while the PTO is engaged.

 

 

I can see the stubs of the purple, green, and brown wires sticking out of the plug that connect with the bundle at the top of the picture.

 

Some other hints while you are at this on a 40 year old machine that may have been through many hands and not always treated well.

- I can see a lot of rust around the black wires bolted to the frame. These are grounds and it’d be good to remove, clean, and reinstall to make sure they are making good electrical contact. Same goes for any other grounds.

- On the visible switch, the leftmost terminal (with the green stub of wire protruding) has a scorch mark adjacent to the switch body “NO3” label. That indicates heating from a poor connection inside the plug at the terminal on the switch--that’ll need cleaning as well.

- Do not totally rely absolutely on the color coding of the wires as seen in the wiring diagrams--double check by tracing the wires per the diagram. Even if a previous owner has not altered things, the factory was not always consistent!

- Its not at all uncommon to find that previous owners have tried to “improve” the wiring to suit their own desires. If you can, putting things back to original configurations is the safest.

Thank you for all the advice! I’m only seeing the 1 switch in that area. Possible the other one was removed? I don’t see any loose wiring that’d go to another one. Also, do you think it’s be easier and safer bet to find a replacement switch? I’ve noticed while looking for other parts some can be tough to find replacements. I’ll make sure to clean up those grounds there’s a few elsewhere needing some work but for the most part wiring seems to be ok other than this switch. I did find the model # 4120OE02. I tried finding the year through quite a bit of searching/reading, possibly a ‘91 but I’m sure you or others may be able to confirm/correct that. 

[Blasterdad 3,044]

1991  

to 

 

Edited January 4, 2023 by Blasterdad

[Blasterdad 3,044]

38 minutes ago, Brad520H said:

Also, do you think it’s be easier and safer bet to find a replacement switch?

I would only replace the switch if it doesn't work.

It's really easy to test with an ohm meter or test light...

[Handy Don 13,507]

59 minutes ago, Brad520H said:

Thank you for all the advice! I’m only seeing the 1 switch in that area. Possible the other one was removed? I don’t see any loose wiring that’d go to another one. Also, do you think it’s be easier and safer bet to find a replacement switch? I’ve noticed while looking for other parts some can be tough to find replacements. I’ll make sure to clean up those grounds there’s a few elsewhere needing some work but for the most part wiring seems to be ok other than this switch. I did find the model # 4120OE02. I tried finding the year through quite a bit of searching/reading, possibly a ‘91 but I’m sure you or others may be able to confirm/correct that. 

I'm pretty sure you have this your “E” is an “8":

41-20O802     A 1991 520-H (20hp Onan engine, hydrostatic transmission, hydraulic lift)

 

(click below to download the file)

Looking at the wiring diagram (which is in the above file) it is correct to have only one PTO switch on that model of tractor.

 

Unless the switch is failing, I wouldn’t bother trying to source a replacement, though they do exist. Since the most common issues are bad connections, @Blasterdad is on the money--test light or meter to be sure. Once I clean my connections, I lightly coat with dielectric grease to inhibit future corrosion.

 

[Achto 29,058]

@Brad520H

 

If you decide to replace the terminals you will need some like these.

https://www.amazon.com/Baomain-Female-Terminals-connector-insulated/dp/B01MFEDLM4/ref=sr_1_51?crid=N4RWAD7B0G9O&keywords=spade+terminal+connectors&qid=1672879674&sprefix=spade+%2Caps%2C120&sr=8-51

[oliver2-44 10,480]

Looks like the guys have you headed in the right direction.

When you have time, 

[Ed Kennell 40,962]

16 hours ago, Handy Don said:

There should be two switches there, “stacked” side by side

Here are a couple pics of the two PTO switches on my two 1988 520s.  The switches are actually stacked on each other.

 

Top view

 

Side view of one I am rebuilding.  I have the bottom switch temporally disconnected.

 

[Brad520H 17]

21 hours ago, Handy Don said:

I'm pretty sure you have this your “E” is an “8":

41-20O802     A 1991 520-H (20hp Onan engine, hydrostatic transmission, hydraulic lift)

 

(click below to download the file)

Looking at the wiring diagram (which is in the above file) it is correct to have only one PTO switch on that model of tractor.

 

Unless the switch is failing, I wouldn’t bother trying to source a replacement, though they do exist. Since the most common issues are bad connections, @Blasterdad is on the money--test light or meter to be sure. Once I clean my connections, I lightly coat with dielectric grease to inhibit future corrosion.

 

Thank you I’ll give it a test. The wiring diagram is appreciated it’s the first one I’ve seen in color so that’ll make it a little easier reference as long as the wires I have match up correctly.