Wheel Horse 520H Wiring Questions

[Ed729 57]

Hello,

 

I recently purchased a 94 520H that according to the last owner just needed a battery. Turns out it also has some electrical issues that also need addressed as well as many other issues which were not disclosed. I have studied the Wheel Horse wiring diagram for my model but unfortunately I’ve found someone has done some re-wiring and so my tractor doesn’t exactly match the diagram anymore. There’s a white wire at the front of the engine near the starter. I don’t see anything in the diagram that would be at the front of the engine with a white wire. I don’t think it’s for the starter relay because I already have a blue wire up there. I assume the starter is self grounding. Any idea what the white wire is for? Im basically just trying to get the tractor running for now and see if it’s worth saving or I should part it out. Picture shows the wire in question near the dipstick tube. Thanks in advance!

[cleat 4,987]

Likely for the engine overheat light.

The sensor is the same one used to ground the headlights.

 

[Achto 26,576]

The wires on the engine should go to a 9 pin connector and from there to the tractor dash, chassis, etc. If you can not rely on the wire colors, use an ohm meter to trace each wire out it see were it goes. Time consuming but it will tell you for certain which wires are which and what they go to. The wires should not be connected to anything on either end when you are tracing them out with an ohm meter. This avoids false readings do to coils, lights or switches.

[953 nut 51,798]

I cringe every time I read a post that involves previous owner wiring. First step should be to clean and tighten all electrical connections including grounds. Many of these connections are near the battery and have been subjected to acid fumes for three decades when the battery is charging.

Best bet is to use the diagram to verify what is correct and mark those wires with some masking tape so you know it doesn't need further study. Download the color copy of the wiring demassification guide for your tractor and look at each function identifying the wires that may be in question. @gwest_ca has the wiring diagram for each circuit color coded for us, thanks Garry.  Make some notes about the functions that are not working and study the page that covers that function.

Good luck and let us know what you find.

 

[Ed729 57]

Thanks all. I do have the wiring guide mentioned  I’m trying to cover my basics first such as getting power from battery to fuse blocks, regulator to battery, key to starter/coil, etc. I’m planning to bypass all safetys and relays for now. Basically I want to use the key to control the starter and ignition to see if the engine will run, check hydros etc. so I can decide if the tractor is a keeper or will be parted out. I’ve never heard it run so I don’t want to spend a bunch of time on wiring until I know it has good “bones”. 

[Ed729 57]

23 hours ago, cleat said:

Likely for the engine overheat light.

The sensor is the same one used to ground the headlights.

 

Ok so I’m guessing by how that looks in my picture the sensor broke off? Not sure what it should look like. 
 

Got it to start and run today by shorting the tan to blue wire and orange to yellow wire in the relay blocks. The key works without all the safety’s now. The hydro appeared dead for the first minute or so but after removing the cam and actuating it by hand back and forth it started working. So I might have a keeper here. 😀

[Wayne0 296]

On 3/9/2023 at 7:07 AM, 953 nut said:

I cringe every time I read a post that involves previous owner wiring. First step should be to clean and tighten all electrical connections including grounds. Many of these connections are near the battery and have been subjected to acid fumes for three decades when the battery is charging.

Best bet is to use the diagram to verify what is correct and mark those wires with some masking tape so you know it doesn't need further study. Download the color copy of the wiring demassification guide for your tractor and look at each function identifying the wires that may be in question. @gwest_ca has the wiring diagram for each circuit color coded for us, thanks Garry.  Make some notes about the functions that are not working and study the page that covers that function.

Good luck and let us know what you find.

 

Thanks for this info. On my 520H the PO ran it with a bad regulator and fried the 9 pin. Wires were cut and spliced to bypass it. Also one wire to the fuse block was cut and spliced with an inline fuse instead. It runs fine as is, but it would be nice to get it back to normal.

[Ed729 57]

41 minutes ago, Wayne0 said:

Thanks for this info. On my 520H the PO ran it with a bad regulator and fried the 9 pin. Wires were cut and spliced to bypass it. Also one wire to the fuse block was cut and spliced with an inline fuse instead. It runs fine as is, but it would be nice to get it back to normal.

Lol maybe we have the same previous owner. I think my 9 pin is missing and I found crimp connectors that had the regulator and battery wire mixed up. 

[cleat 4,987]

14 hours ago, Ed729 said:

Ok so I’m guessing by how that looks in my picture the sensor broke off? Not sure what it should look like. 
 

Got it to start and run today by shorting the tan to blue wire and orange to yellow wire in the relay blocks. The key works without all the safety’s now. The hydro appeared dead for the first minute or so but after removing the cam and actuating it by hand back and forth it started working. So I might have a keeper here. 😀

This is the best picture I could find on my computer of this sensor.

Picture shows a black wire connected to it but I know some of my 520's use a white wire for this.

 

 

Picture also shows the inline sealed fuse holder zip tied to the dipstick tube that connects the charge output

on voltage regulator directly to the battery connection on the starter solenoid taking the load off of the 9 pin engine connector.

 

[Ed729 57]

On 3/10/2023 at 1:16 PM, cleat said:

This is the best picture I could find on my computer of this sensor.

Picture shows a black wire connected to it but I know some of my 520's use a white wire for this.

 

 

Picture also shows the inline sealed fuse holder zip tied to the dipstick tube that connects the charge output

on voltage regulator directly to the battery connection on the starter solenoid taking the load off of the 9 pin engine connector.

 

Thanks for the sensor pic, that confirms my suspicion. 
 

Did you add the fuse or did it come from the factory on some years? My regulator is at the back of the engine and fused through the main fuse block so it’s a little hard imagining a fuse at the front on my setup…I also don’t see it in the 1994 wiring diagram.

[cleat 4,987]

Regulator is in the same place on all engines.

The early models (88 & 89) had a fuse like I show.

That is where I got the idea.

 

Here is the early wire diagram.

Wheel horse 520H wire diagram.pdf

 

Since I have converted all of mine this way, I have never had any issues with the 9 pin connector as most of the constant electrical load is removed from it.