1988 520H Electrial problem

[pgiro 36]

Hello,

 

My lights recently stopped working as well as the tach and a couple other gauges.

I suspect a grounding issue since they all seemed to stop working about the same time.

I checked the fuses that I can see and have looked for any loose wires or ground connections but haven't found anything.

Any common grounding or electrical issues with the 520H that someone can point me to to help resolve this?

 

thanks in advance.

[953 nut 59,281]

There is a pink wire from the "A" terminal of your ignition switch that feeds a 10 amp fuse and continues in to the gauges and your light switch. The fuse holder could have some corrosion in it or there could be a bad connection on the pink (could be black with a pink tracer line) wire.

[gwest_ca-(File Mod) 11,393]

 

[pgiro 36]

Thanks for the tips on this. I checked the pink wire from the ignition switch and checked the 10a fuse on the right side of the tractor.

Everything looks fine from what I can tell, so the search goes on for the problem. Will report back once I find the problem.

[Handy Don 13,695]

1 minute ago, pgiro said:

Thanks for the tips on this. I checked the pink wire from the ignition switch and checked the 10a fuse on the right side of the tractor.

Everything looks fine from what I can tell, so the search goes on for the problem. Will report back once I find the problem.

If you have a meter, start following the pink wire back from gauges to ignition switch looking for where the power stops!

[pgiro 36]

I have 12v getting to the light switch so it looks like it's the toggle light switch that is the problem.

Are there replacement switches available or has anyone seen a similar one on eBay, etc.?

 

thank you.

[lynnmor 7,723]

Take the switch to auto parts stores, they might be able to help.  Also measure the opening and check with Del City.

 

A faulty switch still doesn't explain the other items not functioning.

[pgiro 36]

Thanks for the info about a replacement switch. You are correct that it doesn't explain the other items not working.

 I believe I found the source of that as well, I just hadn't had a chance to report back on that yet..

 The electrical problem actually got worse than that the other day. I went to start it after the big snow storm we got in NE and it was completely dead.

 I noticed that there was a broken connection to a small component on the left side that has what looks like a vacuum tube that goes toward the carb.

 Maybe this is what's shown as the air cleaner sensor in the wiring diagram, not sure what it is. Anyways, one of the spade connectors was broken off.

 Once this was repaired, the tractor started and all the gauges work again as well.

 You wouldn't think that something like that would completely kill the tractor so I'm curious what that little sensor with the vacuum hose is for and why it's so critical to operation.

 

 

[lynnmor 7,723]

That vacuum hose goes to the inboard side of the air filter.  When the filter becomes clogged a vacuum is formed sufficient to operate the switch you found.  It is common for these expensive switches to break, I once had the original source where I could buy them at a fair price, but that is becoming difficult.  Search for this part number, maybe you can find a source: psf101-8111-150.  I have repaired the switches by dressing the nipple side flat and making an aluminum plate with a nipple that is sealed to the dressed surface.  Since your switch has additional issues there may be no way to repair it.  All the switch does is turn on the air filter warning lamp.  If you had an electrical problem there it was just a poor contact where the wires connect to each other.  Whatever you do, plug the vacuum hose if it is open to prevent dirt from being drawn into the engine.

[Handy Don 13,695]

3 minutes ago, lynnmor said:

dressing the nipple side flat and making an aluminum plate with a nipple that is sealed to the dressed surface

Hey @lynnmor, if not too much trouble, can you share a pic of this?  I've been trying to hack something like this but none have held up. (In between fails, I've been hooking the sensor end of the tube to the other side of the sensor, the pressure side, to keep it closed! So, if the air filter internal pressure rises above 20psi, it'll light up the indicator and I'll be in deep trouble.

BTW, you might enjoy a bit of inventive wiring.  Since I've merged the topside of a 518-H to the chassis of a 520-H, I discovered that I had a transmission temp sensor but no dashboard indicator light to wire it to.  Not wanting to let a good sensor go to waste, I ganged it with the air filter sensor output! So now if I see that light it'll either be the tranny or (once the sensor gets a working nipple) the air filter.

[953 nut 59,281]

22 hours ago, pgiro said:

one of the spade connectors was broken off.

 Once this was repaired, the tractor started and all the gauges work again as well.

You probably should inspect the other wiring connections on your tractor. Seldom do you see one failure and everything else is pristine.

[lynnmor 7,723]

1 hour ago, Handy Don said:

Hey @lynnmor, if not too much trouble, can you share a pic of this?

 

Here ya go:

 

[pgiro 36]

Thank you for the info about the air cleaner sensor. Like you mention, it should only turn on the air filter warning lamp so it should not prevent the tractor from running.

So I don't know if that is the actual problem or it was just a coincidence that I had a broken wire on the air cleaner sensor. So tonight I started up the tractor to clear more snow. It started right up. Like I mentioned earlier, I think the light switch is bad, so thinking that I would like to have lights while I was clearing snow, I figured I'd pull the wires off the light switch in the dash and put the connections onto another switch I had lying around. Not only did the lights not turn on but it killed the tractor completely. It shut off immediately and it is completely dead again. Very weird. I checked the 10a fuse and it is fine. Doesn't make any sense to me.

[953 nut 59,281]

The ten amp fuse and light switch have nothing to do with your tractor starting and running, Chances are there are wires near the light switch that need attention.

[lynnmor 7,723]

Did you inspect the white 9 pin engine connector, usually located near the battery? 

[pgiro 36]

I did not inspect the white 9 pin but I will take a look at that. Thank you.

[Handy Don 13,695]

14 hours ago, lynnmor said:

 

Here ya go:

 

Thanks.  I see you went big and covered the entire face. My attempts didn't go as far out and failed. Lesson learned.  

What did you decide to use for sealing the plate to the face and for securing the ⅛" tubing in the metal plate to form the nipple?

[lynnmor 7,723]

I made the aluminum part from a solid, the nipple is incorporated in that.

 

I put a groove in the block to hold a tiny o-ring.

[Handy Don 13,695]

24 minutes ago, lynnmor said:

I made the aluminum part from a solid, the nipple is incorporated in that.

 

I put a groove in the block to hold a tiny o-ring.

Ok, I did ask and you were gracious to answer.

Still, that is just plain superman stuff and way out of my realm of tooling and abilities! 

Last question: It looks like the sensor mounting screws are not holding the plate to the sensor body, so what keeps that o-ring in compression between them?

[lynnmor 7,723]

1 hour ago, Handy Don said:

Ok, I did ask and you were gracious to answer.

Still, that is just plain superman stuff and way out of my realm of tooling and abilities! 

Last question: It looks like the sensor mounting screws are not holding the plate to the sensor body, so what keeps that o-ring in compression between them?

There are small screws thru every thing where the rivets are, you can barely see the ends flush with the block.  The washers behind the switch is to allow for the screw heads.

Edited February 8, 2021 by lynnmor

[Handy Don 13,695]

38 minutes ago, lynnmor said:

There are small screws thru every thing where the rivets are, you can barely see the ends flush with the block.  The washers behind the switch is to allow for the screw heads.

Ah! Got it. So you took out the original rivets holding the sensor together and replaced with screws. Very surgical. I like it.   

Thanks for the insight.  I've got a plate I can cut down, drill and tap.  I'll send a pic of what I come up with once I get the nipple thing solved.

[lynnmor 7,723]

2 hours ago, Handy Don said:

Ah! Got it. So you took out the original rivets holding the sensor together and replaced with screws. Very surgical. I like it.   

Thanks for the insight.  I've got a plate I can cut down, drill and tap.  I'll send a pic of what I come up with once I get the nipple thing solved.

 

Its been a few years but I think that I used 2-56 screws that were small enough to go thru the holes in the rivets.

[pgiro 36]

For anyone interested and for future reference, looks like you can get the light switch for the 520 here:

https://wheelhorsepartsandmore.com/product/107-9238-headlight-switch-for-wheel-horse/

[pgiro 36]

It turns out that the problem seems to have been the PTO switch or the associated wiring. After I removed the connections and fiddled with the switch a bit, the tractor started up normally.  What confused things was the light switch was bad (which I knew) and it turns out the test switch for the status lights had gone bad too, which made it a bit confusing to troubleshoot since I was getting no signs of life whatsoever from the tractor. The broken wire to the air cleaner sensor was also a false positive since it  only powers a status light on the dash. The wiring diagram provided was very helpful.

So I'm back in business and ready to move some more snow tomorrow.

 

Thank you to everyone for your help.