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mikeeyre74

Hour meter to oil sensor to pulling my hair out...

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I think I'd rather stick my face in a bear trap than have to take Onan twin engine sheetmetal off ever again. Gah. Maybe I'm just not doing it right, but I'll be damned if that's not a really complicated hard to remove mess. 

 

Situation: Hour meter doesn't work

 

I understand the hour meter listed to the oil pressure sensor to ground it and start the meter running. I noticed my meter isn't working, so I turned the key on and jumped the ground to battery with a test lead and she fires right up and clicks, so I know it's just not grounded. This led me to trying to find the oil pressure switch and then wanting to harm myself by hassling with that damned sheetmetal that was in the way. 

 

I did find a dead mouse behind the cover, so it was, all in all, a good thing. 

 

Anyway, I can't figure out how to test the system now before I put it back together? I can't run the engine to get the pressure to build because I have all the wires and fuel stuff disconnected and moved out of the way to get the shroud off. Is there a way to test the oil pressure sensor without it running? Is there a way to test the whole system then, without it running? I'd have thought jumping the two spade connectors on the pressure switch would have made the hour meter start running, but it doesn't... what gives? 

 

Mike

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I had the same problem  1 1/2 years ago on my 520H. I had to put it back together  In  order to see if the  hour meter  worked.

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The blue wire at the oil pressure switch grounds the oil light when the pressure is low or 0.

The black wire at the oil pressure switch grounds the hour meter when there is oil pressure.

 

Two totally separate circuits controlled by two circuits in a single pressure switch.

 

Garry

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You could cut the ground wire and just run a new one to the chassis or battery ground. It won't be correct and will add hours if you leave the key on but at least it will work. 

 

I have a different problem with mine. The meter works when it wants to and it's not losing power or ground. Bad meter. :(

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All of my 520's came with non functional hour meters so I do not know for sure how many hours are on any of them.

 

3 of them now have electronic digital hour meters and one has a new Hobbs replacement.

 

All of them are wired with their own ground so will work even if engine is no running but I don't know why I would leave the key on without engine running.

 

 

 

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5 hours ago, gwest_ca said:

The blue wire at the oil pressure switch grounds the oil light when the pressure is low or 0.

The black wire at the oil pressure switch grounds the hour meter when there is oil pressure.

 

Two totally separate circuits controlled by two circuits in a single pressure switch.

 

Garry

 

 Any idea of an easy way to test this set of circuits without having the engine running? 

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You would need to remove the switch and come up with source of applying a controlled pressure to the switch. The easiest may be a hand tire pump connected to a low pressure gauge and the switch.

Garry

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 If I'm reading this wiring diagram correctly,  if I hook a test light from the positive terminal of my battery and touch one of the switches probes with the engine off, one of them should light the lamp and the other one should not.  Then, if the engine is spinning, that same terminal should turn the light off, but should be  lit up on the other terminal, is that correct? 

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:text-yeahthat:           Sounds right to me.

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And failure! I went and pulled the switch out and tested it in hand and under pressure. NO function at all, no matter what I do. It's internally mucked up. I can't seem to find a good replacement part number.. this ones listed as NLA. Onanparts.com is "gone fishing" until november.. Anyone got a lead on a replacement?

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Lots of Onan low oil pressure switches on ebay.

 

No Wheel Horse specific ones right now but there usually is.

 

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So then... if the original part isn't available anymore, but you can still get the one terminal ones, if I installed that (connection made at 5psi style), I could line that back up with my hourmeter and make that circuit run again... but my idiot light for the low pressure would be DOA. That's the magic of the two circuit switch, correct?

 

OR:

 

Does it make more sense to wire the hour meter up with its own ground off of the oil pressure circuit (have to go with Key ON action and try and remember not to just leave it on..)  and use a different oil pressure switch which would be mormally CLOSED at 0psi and open at pressure above that and have that wired in with the idiot light? That would be safer I guess?

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The older 520's came with a single contact pressure switch.

That controlled the flashing oil light only.

The hour meter ran when key on irregardless of engine running or not.

 

Wheel horse 520H wire diagram.pdf

 

Cleat

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What years would that be on so I can get a pressure switch like that, then? Or, better yet, if you have the part number in your head that's fine too...

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After a little research, it looks like this PS122 switch from Wells would work, yes? It has three terminals on it, but looks like it's a NC/NO action like the two position original equipment, but the third terminal works in mirror to the 1st teminal. If I ignore that extra terminal, it will function as I need it to. And at $6, it's not a bad deal!

 

http://www.wellsve.com/showall_ds_oil.php

 

Can anyone confirm? Its NC at 0psi, and opens at 2.5 to 12 psi on the other terminal, according to their site that  linked above.

 

Mike

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I answered my own question. For anyone following this thread, read this:

 

 

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