jd 870 pto question

   / jd 870 pto question #1  

bigkuhna99

New member
Joined
Jul 1, 2012
Messages
6
Location
Carlilse PA
Tractor
jd 870
Engine shuts off when I put pto in gear. Any idea were the PTO safety switch is?
 
   / jd 870 pto question #2  
bigkuhna99 said:
Engine shuts off when I put pto in gear. Any idea were the PTO safety switch is?

Are you asking about the rear or mid?
Shoot me your email at Ron@opfa.com and I'll scan a couple diagrams.
Ron
 
   / jd 870 pto question #4  
The PDF document is to large to upload and attach showing the PTO linkage etc. If you e-mail me I can send it directly to you. It may not be relevent because it does not show the switch specifically, but my guess is it is on the left side of transmission housing.

Howerver, looking at the electrical diagram which I was able to upload and based on the following thought process, my guess is the switch is working.
I beleive the PTO switch is closed when in neatral and open when PTO is engaged.
I am assuming you are sitting on the tractor seat with the tractor running, clutch depressed when you engage the PTO
If we assume every thing else was working
If the rear PTO switch was stuck open indicating the PTO was engaged the tractor should not start.
The fact that the tractor stops when you engage the PTO indicates - probably the PTO switch is changing states (going from closed to open). If the switch was stuck closed engaging the PTO would not make a difference.

I'm wondering if the seat safety switch is fauly or possibly the time delay control. which kills fuel to the engine depending on a couple different conditions.

I'll try a couple things on my tractor over the 4th and e-mail you. Note I will not have my computer at home so this will be by smart phone so I can not send diagrams.

Maybe you can give me some other specifics. I would suggest you try this with the seat safty swich pulled up. Also try it with the transmission in neutral.

Best wishes and happy 4th.
 

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   / jd 870 pto question #5  
BigKahna99

As I mentioned in our e-mail exchange I thought I should post the suggestions and results for the benefit of the other members and future searches. Here is the string in chronilogical orrder (with private e-mails deleted).

:confused: On Jul 3, 2012, at 6:24 PM, - BigKahna99 wrote:
I am new to this type of repair but willing to try anything. It runs fine until i try to engage the rear pto then it just shuts off. It's the same if I'm on or off the seat.


:2cents: Wednesday, July 04, 2012 9:10 AM JD 670 Wrote
Subject: Re: pto issue
I spent the evening looking over the schematic diagram and have three tests to try, but this is predicated on you having already conducted the periodic operation safety test already and that is normal. This also assumes you you have a Mid PTO and it is in neutral
Please be safe

#1 - with the transmission in neutral
Rear PTO in neutral
Not on seat (either standing to the side or raise seat and use seat support rod and sit down)
See if tractor will start.

#2 - with the transmission in neutral
Rear PTO engaged (no equipment attached to PTO)
Not on seat (either standing to the side or raise seat and use seat support rod and sit down)
See if tractor will start

#3 - with the transmission in neutral
PTO in neural
Start tractor you should be able to dismount the tractor,
raise seat, pull up the seat switch, use seat support rod and remount and sit down.
Now engage Rear PTO

It should start in # 1
It should not start in #2
My guess in #3 is the tractor will not die when you engage PTO

If this is true I think you have a bad time control module and more specifically the top left diode is shoot.

Let me know the results of your tests

Good luck

:confused: On Jul 4, 2012, at 12:05 PM, "BigKahuna99wrote:
getting close, here are the results
1- it started
2- did not start
3 - It stayed running. both tractor and PTO run

BUT when I put in into gear to move forward with the PTO running the engine shut off.
I really appreciate all the time you have spent working on this with me!


:2cents: Sent: Wednesday, July 04, 2012 3:53 PM
Subject: Re: pto issue
BigKahuna99 - Thanks for adding the additional info about putting it in gear. That pretty much confirms the transmission neutral switch and the PTO neutral (not engaged) switches are working.

Bad news it Almost certainly it is the Time delay control module. This is located under the gauges on the right side.

I can't find how an open connection, like a bad plug, would cause this. But I will keep looking

I'm guessing the TDC module is not inexpensive. A work around would be to jumper the following wires together at the seat switch connector. Yellow/Red wire to Blue/Black wire

Alternatively You could do this at the plug under the steering wheel (need to pull the panel cover with ignition switch -5 screws) but you won't have much room to work.

If you do this jumper do not try to operate with the seat switch pulled up. I don't think it would hurt anything but some of the safety interlock logic will not be working.

If you have access to a electronics supply and can find a diode that will handle 3 amps you could put this rather than a hard jumper in place. The positive side of the diode would go to Yellow/Red wire and the negative to Blue/Black wire.

I'd try the jumper first and see if it works then go for diode. With the diode installed the safety interlock logic should be intact. You could use heat shrink to cover the diode and junctions.

Thank you for the thanks. I used to be an electronics manufacturing eng. this keeps the grey matter working and I may needed it on my 670 one of these days.

Hope you have/had a great 4th. :cool2:

PS I might post the test and solution once we/you resolve this so your post/thread has a conclusion.

Sent by iPhone :thumbsup:
 
 
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