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John Deere 318 Electric Pto Problem


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#1 bbundy OFFLINE  

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Posted July 07, 2014 - 07:03 PM

My John Deere 318 mower deck is giving me trouble.  It dis-engages every 30 seconds or so.  I can't figure out why.  I tried running the engine faster, raising the deck, going really slow to avoid rocking the deck -- nothing seems to help keep the pto engaged.  Any ideas what could be wrong?


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#2 JD DANNELS OFFLINE  

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Posted July 07, 2014 - 08:47 PM

yes I have a pretty good idea where to start since this has happened to me as well. There is a relay on the front crossmember and I have had the connector vibrate loose causing intermeidate contact. Or you could have a loose wire on the PTO switch.
Then if those do not work check the safelty switches. But they should shut down the engine if your not on the seat and the PTO is switched on. I am assuming you have the air gap on the clutch set correctly?
I am working off memory but with the engine not running the air gap should be between .014 and .018. I usually split the difference and set mine at .016. CHECK THE SPECS BUT I AM PRETTY SURE THAT IS RIGHT. BTW welcome to the forum!!

Edited by JD DANNELS, July 07, 2014 - 08:49 PM.

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#3 JDBrian OFFLINE  

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Posted July 08, 2014 - 05:10 AM

Welcome to GTTalk. As said above, the connections on these older tractors can become dirty, loose or corroded and lead to electrical problems. Have a look at the wiring harness and remove each connector, looking for burnt or discoloured/melted wires, loose connectors and clean them with a good contact cleaner to rinse out dirt/ grease that tends to build up. I'd also check the battery voltage while running with the deck engaged. A low voltage to the coil could cause it to drop out. Hopefully it's not the clutch itself. They are an expensive part to replace.


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#4 bbundy OFFLINE  

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Posted July 08, 2014 - 03:14 PM

Thanks so much - these are great suggestions.  I will have some time tomorrow to follow through on these ideas.  I will definitely let you know which of these ideas solved the problem. 


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#5 bbundy OFFLINE  

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Posted July 09, 2014 - 06:03 PM

OK - checked the PTO plate gap, cleaned the plates, and checked voltage going to pto (12 volts).   After this I tried testing and got a completely different set of symptoms.  The engine started cutting out on me then it finally quit running.  I can start it with the brake on but a soon as I try to lift my foot of the brake it stops running.  So I thought it must be the safety switch under the seat so I bypassed it with a piece of wire but that didn't help.  I checked to see if I'm getting voltage  to the seat safety switch and I am.  So the only thing I can think of is that there is a loose wire on the return that isn't allowing the seat safety system to complete the loop.  

 

Does this sound like correct thinking?  If so,  where do I look for the loose or frayed wire?

 

Again thanks for any advice you can offer me.

 

Frustrated in WNY. 


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#6 JD DANNELS OFFLINE  

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Posted July 11, 2014 - 07:16 AM

I am not at all sure if this is your problem, but there is a micro switch behind the dash that assures that you can not start the machine in gear. I had that need adjusting once. The switch is square with an arm on it and the arm contacts the shift selector linkage.

The wiring for your seat safety switch along with the taillight wires are ran under the seat pan and on top of the gas tank. There are only 4 bolts that hold the seat pan on, but it is pretty awkward to lift it on and off by yourself. This i know because I had to replace all my fuel lines and the pickup in the tank a couple weeks ago.

Edited by JD DANNELS, July 11, 2014 - 07:21 AM.





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