OPC CB blows. Operator Protection Circuit

KauaiJohn

Member

Equipment
B3030HST
Apr 25, 2011
33
0
6
Kalaheo HI
Yeah, only 2. That's why I'm so baffled.

And why I'm so concerned with a short in between.

Thanks tooljunkie

I've tested the wires with an ohm-meter for that circuit in as many ways as I can think of, which is probably only a fraction of the possibilities (sigh), things work like they're suppose to.

If you can think of some way-outside-the-ordinary reason for a short when none of the testing I've done even hints at such, please share.

We'll bestow the "Tesla" award on you. Maybe even get you a ride on a SpaceX capsule. (Just trying a little levity since I think I'm asking a dumb question. But if someone has a smart answer, that's fine with me. I just want it to work.)
 

North Idaho Wolfman

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Jun 9, 2013
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A couple of things could be happening.
One: The input and/or output of the switch is shorting to the case of the switch, this may only be happening very randomly.
Second: There may be bad contacts in the switch that are causing the circuit to rise to high in resistance thus overloading the circuit thus blowing the fuse. ;)
 

Grouse Feathers

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All I have is a BX tractor and schematic so this may or may not help. Going back to your original post you said one time you got off with the PTO engaged and it did not shutdown. I am not sure it is supposed to shutdown with the PTO engaged unless you get off the seat and the tractor is moving.
My BX schematic shows two contacts for the PTO switch one for shutdown if the tractor is moving and the PTO is engaged, and the second to prevent starting if the PTO is engaged. If the fuse blows when you turn the key on I would suspect the seat / PTO shutdown circuit, if it blows when trying to start I would suspect the PTO starting circuit. If it is the starting circuit it could be the wiring or the starter solenoid.
I hope this helps.
 

Daren Todd

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Does someone have the wiring diagram that they can post for the op's tractor?
 

Jim L.

Active member
Jun 18, 2014
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Texas
Just to be clear, with the switch removed, I would make a jumper to go into the connector. Then see if the fuse blows. If it does, then the problem is downstream or in the connector.

If you don't have pins to fab a jumper, then fold the bare end of the jumper wire until it stays in the female pin of the connector.
 

KauaiJohn

Member

Equipment
B3030HST
Apr 25, 2011
33
0
6
Kalaheo HI
SUCCESS!

It was the independent PTO lever switch. (not the PTO select switch although the part number for both is the same.)

It took so long to fix because I kind of wanted to support the local business. I paid for 2 day shipping $36 for a $20 switch and it still took two weeks to arrive. Guess I won't be supporting the local business any longer.

It is necessary to remove the seat and the sheet metal holding the seat. The electrical connector on the top of the switch rotated freely. It has a unique latch system that took a while to figure out because dirt prevented it from working correctly. The switch was not seated either.

I was able to determine that was the broken switch by finding the correct leads from the OPC controller and using an ohm meter. The circuit was always closed whether the PTO lever was engaged or not. (There was brief point halfway between engaged and not where the circuit would open.)

After I removed the switch I used the ohm meter again to the switch leads and confirmed that no matter what the position of the ballbearing, the circuit was always closed. While this is obviously broken, it still is not clear how this could cause the OPC fuse to blow. All it should do is keep the engine running when the operator gets off the seat and the PTO is still engaged. I checked the wiring and was unable to get a completed circuit no matter what I did, which could mean I just didn't to the "right" thing.

I had to purchase a 15/16" deep socket to screw it in tight. I realize it should have been mm, but the mm sockets did not fit. I could not get an open wrench into the area.

If you don't hear anything else from me, I guess it means its fixed for now. ;-)