John Deere 6400 PTO will not engage

[Moggytom]

Have John Deere 6400 4WD and have not used the PTO all winter. went to use it now and the PTO knob when lifted and turned to right does not start the PTO but the light comes on to say the PTO is engaged. it was working perfectly last time I used it. does anyone have any suggestions ( I am a novice with John Deere tractors). I have turned the tractor on and off as I read there was an auto cut out if the PTO was engaged when the tractor was turned off. But that did not work. wondered if there may be a relay or fust that might affect it?

 

[Suffolksucklers]

Stating the obvious here, but assume you have it in gear, i.e. 540/1000 etc

 

[Moggytom]

Yes it is in 540 but that gear lever will not move it has never gone into 1000 but I am sure it used to go into 540E but it won’t now. I may be wrong as I am a novice and never drive the tractor much it was my husbands tractor I only drove it on ocassions muck spreading but it is strange because I spread some muck in autumn and it was working fine then and I haven’t touched it since.

 

[Tractortech]

Now Then..
As a test, you can remove the coil from the differential lock solenoid (rhs of rear diff housing) and exchange it with the rear PTO coil (on top of the rear diff housing to the right of the top link bracket) see if it works then,,, 🛠
If yours are both the square type, use a 19mm spanner to undo the nut on the top and swap them over. If you have the newer round type, it won't swap..

 

[marco]

Does it have the mudguard switch? If so that could be full of moisture and be causing your issues

 

[jd6420s]

I had a very similar problem last year and Tractortech helped solve that problem using the advice given above. The PTO had never given any indication that it wasn't going to fail to engage. I had left it for a couple of months and came back to it only to find nothing happened when I tried to engage the PTO. The square coil (NO 2 in the first image) was on pretty tight and wouldn't move even when I removed the nut on top. I took it to the local dealer who separated it from the solenoid and cleaned it up to make a good contact. They connected it up to a battery and it worked just fine in the workshop. It just didn't work when I put it on the tractor. Changing it over with the Diff lock one proved that it was the coil that was to blame. I would try that first before looking under mudguards.
If the coil is to blame dealer prices are £150 for the coil or £450 for a complete new unit. Other places will be cheaper.

 

[Moggytom]

yes it does have mudguard switch for hydraulic arms, not sure about the PTO though. But Mud guards have been battered over the years and so you may well be right about moisture getting in if there is a PTO switch. I never use or have used the mudguard switches so will investigate that. How does the PTO work, is it on the hydraulic system or via the gearbox or what? .

Now Then..
As a test, you can remove the coil from the differential lock solenoid (rhs of rear diff housing) and exchange it with the rear PTO coil (on top of the rear diff housing to the right of the top link bracket) see if it works then,,, 🛠
If yours are both the square type, use a 19mm spanner to undo the nut on the top and swap them over. If you have the newer round type, it won't swap..
View attachment 1175931View attachment 1175932

I recognise the second diagram but not the first - does that mean I have the round type so can’t test it this way?

 

[jd6420s]

If it has a PTO switch it will be a bright yellow button on the rear mudguard. To get to the back of the switch you will need to remove the lining underneath. I think there are about 8 screws holding it in place. I would expect these to be badly corroded so could well be difficult to take off. If the mudguards have been battered then they could well be difficult to get the lining back on again.
The second image shows both types of solenoids. There is the all in one (newer) type at the top and the older two piece with the coil (square block) beneath.
Are you able to take a photo?

 

[celtis man]

yes it does have mudguard switch for hydraulic arms, not sure about the PTO though. But Mud guards have been battered over the years and so you may well be right about moisture getting in if there is a PTO switch. I never use or have used the mudguard switches so will investigate that. How does the PTO work, is it on the hydraulic system or via the gearbox or what? .

I recognise the second diagram but not the first - does that mean I have the round type so can’t test it this way?

I bet it's a poor earth connection try making a temporary one at the solenoid.

 

[Moggytom]

ok there appears to be no PTO switch on the mud guard. The design is as in second diagram with the round coil. I do not know how to make a temporary earth connection at the solenoid?, (told you I am a novice, but a capable one in truth with the help of friends like you). the tractor has been working in extremes of conditions with all the wet weather this winter as a very unscrupulous engineering company, who came out to just repair a burst hydraulic pipe, have sabotaged my telehandler transmission, seemingly to make work for themselves, and then when I told them I could not afford to go ahead with their £14,000 quote for the very unbelievable damage they had done to my machine and asked them to return it, have refused to return it unless I pay to have the work done, so have kept my machine in their yard and left me without a telehandler all winter and dependant on my husband's old J Deere. leaving me afraid to let my J Deere go into any Agricultural engineers yard at the moment, as it is now all I have to feed my livestock.
will take a photo today and post it later this evening. Meanwhile attached are photos from the tractor manual. Not sure if they will open or not ???

 

[Tractortech]

I wouldn't start cutting any wires and making temporary earths. I've never had an earthing issue with one of these. Do you have such a simple thing as a 12v test light??
It's very rare for a 6400 to have mudguard PTO switches, so let's not worry about that..
Can you put some pictures of the actual tractor on here, solenoid valve, overall picture of the back of the tractor and a side view, one of inside the cab too...

 

[Moggytom]

I wouldn't start cutting any wires and making temporary earths. I've never had an earthing issue with one of these. Do you have such a simple thing as a 12v test light??
It's very rare for a 6400 to have mudguard PTO switches, so let's not worry about that..
Can you put some pictures of the actual tractor on here, solenoid valve, overall picture of the back of the tractor and a side view, one of inside the cab too...

Pictures as requested plus When cleaning up a bit to take pictures found a wire unplugged from what I think must be the solenoid? Could this be my problem? However cannot get it to plug together securely and very difficult to get at behind hydraulic pipes. Plugged it back in but PTO did not work however as I said could not get it to snap right in tight so may be not connecting right. Plug photographed at end of my black gloved finger (incase your wondering what that black thing is )
also think I need to clean my tractor, said it has had a hard time this winter and dog in cab does not help matters

 

[Tractortech]

You have the older style square solenoid and if the wire isn't plugged in it won't work.... However,,,,,,,, is that just a trick of the light, or is your tractor a little dirty?? Seriously though the crap around the solenoid will enter the plug cavity and prevent a good connection.
I would start with the pressure washer (are there some Polish guys operating a car wash locally?).then some compressed air to blow it clean and dry, possibly some contact cleaner too....

 

[jd6420s]

You might struggle to clean the connector on the square coil because it is facing away from you. It will help if you could loosen the 19mm nut on top of the coil. The coil could then move around to a better position to clean it. Reconnect the wire and see if it works. If not you will have to try and remove the coil and do the trick that Tractortech said in his first post. It should just pop on and off if the nut is removed but after 30 years of hard work I doubt it. A bit of WD40 would help.

 

[Moggytom]

You have the older style square solenoid and if the wire isn't plugged in it won't work.... However,,,,,,,, is that just a trick of the light, or is your tractor a little dirty?? Seriously though the crap around the solenoid will enter the plug cavity and prevent a good connection.
I would start with the pressure washer (are there some Polish guys operating a car wash locally?).then some compressed air to blow it clean and dry, possibly some contact cleaner too....

Ashamedly, the tractor is Very dirty! I am an OAP lady, in my 70’s, farming alone, no help but plenty of hinderance and with all the months of wet weather on heavy clay the ground is water-logged and standing in water, so just back and fore to dung heap cleaning out cattle yards poor old JD has to roll through 18”-2’ deep mud daily but she has been a rock to be fair apart from hydraulic pipe and now this current problem which could well be the latest in a continuous ongoing saga of spite and sabotage - looking at photos now it looks like the hydraulic pipe over the top of the square solenoid, which was a brand new loader pipe replaced in about Dec or January this year has been attacked again, will have to check when I go up farm today appears to me like someone is putting some form of acid on various pipes to burn through the outer layers - this was a new hydraulic pipe on my telehandler back last year and had to have two sets of hydraulic boom pipes as well £££££££

anyway thanks guys, I will take your advice give it a good clean try and re-connect the solenoid wire and come back to you with progress - might take me a day or two as have more desperate jobs to get done first.

 

[celtis man]

Ashamedly, the tractor is Very dirty! I am an OAP lady, in my 70’s, farming alone, no help but plenty of hinderance and with all the months of wet weather on heavy clay the ground is water-logged and standing in water, so just back and fore to dung heap cleaning out cattle yards poor old JD has to roll through 18”-2’ deep mud daily but she has been a rock to be fair apart from hydraulic pipe and now this current problem which could well be the latest in a continuous ongoing saga of spite and sabotage - looking at photos now it looks like the hydraulic pipe over the top of the square solenoid, which was a brand new loader pipe replaced in about Dec or January this year has been attacked again, will have to check when I go up farm today appears to me like someone is putting some form of acid on various pipes to burn through the outer layers - this was a new hydraulic pipe on my telehandler back last year and had to have two sets of hydraulic boom pipes as well £££££££

anyway thanks guys, I will take your advice give it a good clean try and re-connect the solenoid wire and come back to you with progress - might take me a day or two as have more desperate jobs to get done first.

@Moggytom are you ok with all this going on? Can you get yourself some help? I know it's been a tough wet winter
Do you know of any other independent mechanic's who would sort your problem?
Your pipes look like they have rubbed especially the one by the orange frame.

 

[Beekeeper21]

Probably You have a problem with BCU (check that part of manual ). Isnt switch of PTO *going* to BCU unit and from that *signal* going to PTO Valve?

 

[Tractortech]

Probably You have a problem with BCU (check that part of manual ). Isnt switch of PTO *going* to BCU unit and from that *signal* going to PTO Valve?

A 6400 doesn't have a BCU ! ! !....

 

[celtis man]

A 6400 doesn't have a BCU ! ! !....

I thought that or a ECU does it?

 

[Tractortech]

I thought that or a ECU does it?

There are NO ECU'S involved. One fuse, o6ne switch, 2 relays and a solenoid valve with some wires in between..
As a side note.. all jd controllers have a 3 letter acronym (TLA)
BCU = Basic ontrol Unit
ECU = Engine Control Unit
EPC = Electronic Powrquad Control

So, the PTO can't be run through an ECU as it's an engine controller..