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316 (Onan) PTO. No power?

5551 Views 28 Replies 7 Participants Last post by  CaptainPete
Recently replaced field coil in my (new to me) John Deere 316. The previous coil was completely ruined when I bought it. When I went to test it the PTO light didn't come on and it didn't send power to the PTO itself. I was able to get the light to flicker, and it engaged for a second. I tested the switch and if I would wiggle it it would flicker. So, I put a new switch in it and now it cant get the light to flicker at all. Is there anything specific I should check? (Fuses, grounds, etc?)
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You may want to get under and check wire connections to the clutch
also.....Did you check the gap on the electric pto?...do you hear any clicking at all when you flick the switch with the key in on ( not running) position?
this video may help
I do not hear any clicking, however, when I had the old switch in, I could get it to click if I would wiggle the switch, hence why I replaced it. The gap is set correctly, and it is plugged in with the one blue wire to the harness and the ground wire ran behind the mounting plate. Perhaps the ground behind the plate is bad?
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That is the next thing to check, or if you have a DVOM (digital volt ohm meter) you can check for voltage at the front plug with the key on and the PTO switch on. If you have 12 Volts DC then it most likely a ground problem. Plus check your fuses too.
All fuses are ok. Checking if there is power to the PTO in front now.
I am getting power to the front. Now would it the ground from the PTO plate
You can go there or to the engine mounting bolts down in the front there. Mine is using the engine mounting bolt to the plate steel. I've used a star washer to help make sure it makes good contact also.
Just tested again to make sure and...lone behold...no power to the front. I dont understand. Loose wire, bad time module?
Loose connection before the switch somewhere? Check everything to include grounds.
Safety switches installed and working correctly? Use the wiring diagram for your tractor along with your multi-meter to determine what's causing the problem.
May not be the same or even close but on my 332 the front electric PTO would not engage by the switch once things were hot. I figured the temp made a wire break somewhere in the winding show up. If I used a screw driver and pushed on the plate with the switch on then the PTO would engage and work.

Bought a new PTO setup and after reading the install directions, which described setting the gap, I decided to try adjusting the gap on the current PTO before changing it and what do you know 鈥 Now that the gap is set correctly it has worked without issue for several summers.

I now have a spare PTO!
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When you had a flicker to the PTO light before and now nothing would suggest that there's a loose connection (or broken wire) somewhere in the circuit, so if you check out each wire for continuity (or voltage) with your multimeter, you should be able to find your problem. I would start at the PTO switch to see if you get 12 volts as input to the PTO portion of that switch (use the wiring diagram for all this, it'll show you the wires and the color coding so you can follow them). If you have power at the switch, turn it on and check the output, then follow each wire leading to the PTO to check for power and this should lead you to where things stop. If you can't figure out the issue, let us know what your results were (using the wiring diagram as reference) and we can give some suggestions.
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So I found an unconnected ground. So I regrounded it and now there is some witchcraft going on. If I turn the key on, PTO comes on no matter what, switch on or off, but only oil and battery light come on. If I disconnect the main battery terminal and ground the wires I found right to the battery, only the PTO light and battery light come on...no oil light.
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Keep checking all the connections and grounds until you've gotten them all cleaned and tight. Strange things happen in electrical circuits if good connections are not in place.
There is usually one loose wire in the pedestal near the PTO switch for daisy chaining over to the rear PTO switch.
As Russ said that wire that was unconnected is probably for the rear PTO and may not be a ground. Disconnect it and see if you get back to your original symptoms.

Try running a jumper from the battery to the PTO clutch and see if it energizes. That will eliminate part of the potential problem. Are you sure you wired the new switch properly. Seems strange that wiggling the old switch got it work and the new one does nothing.


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To be specific that ground I was talking about was 3 black wires running to one single ring terminal. I believe when I repainted the tractor, it was around one if the mounting bolts on the starter solenoid, and I just forgot to put it back on. It did influence the PTO, and I'm slowly narrowing down problems.
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Disconnected that wire got nothing now. I did jump right to the pto and it does click. Also, the switch only goes on one way correct?
Disconnected that wire got nothing now. I did jump right to the pto and it does click. Also, the switch only goes on one way correct?
The switch only goes one way, but internally it has two parts, one part is a standard single pole single throw switch that turns the power to the clutch on and off. The second part is also single pole single throw, but when you turn on the power on to the clutch, you turn this section off - it's part of the safety circuitry and stops you from starting the engine with the clutch engaged. If the wiring has all the factory connector ends on it, it shouldn't be possible to switch the functionality, but if the connectors have been changed, you may have things connected improperly, that's why I strongly recommend that you use your wiring diagram along with your multi-meter, it saves a lot of guessing and burned wires.
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Everything is plugged in on all of the switches with all of the factory connectors. I just cant seem to figure out where those three black wires go to, even with the schematic.
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