Help!! JD1070 - Engine Dies When Engaging PTO in Gear

[tjstence]

Hello,
I recently bought a JD 1070 (2WD, FEL, 8B backhoe, finish mower, box blade). Runs and drives strong, and I've enjoyed using the loader to clean up my small property. Unfortunately, I discovered an issue when I went to cut my grass with the 3 pt finish mower for the first time.

The problem: the engine completely dies/shuts off when I try to engage the PTO with the tractor in gear. The PTO DOES operate fine while the gearbox is in neutral, but as soon as I put it in gear, the engine gets killed.

Am I doing something wrong?

This is my first compact tractor and I'm learning as I go. I believe it's some sort of electrical interlock that's causing the problem, but I'm just not sure where to start troubleshooting. The seat safety switch must have been bypassed by a previous owner because it continues to run fine if I dismount the seat with the PTO running. I can also stand up fine while the tractor is in motion/in gear.
The combination of the PTO engaged and a gear selected IMMEDIATELY kills the engine; it doesn't bog down or stumble. With the PTO running, I can push the clutch in, but as soon as I click it into gear, the engine cuts out even before I release the clutch pedal. With the PTO off, I can clutch in, select any gear any range, and cruise around without any issue.

Has anyone had this issue or have an idea of what could be causing this?
Thanks for any help!!

 

[TnAndy]

Possibly the PTO switch is bad, but probably not since you can run the PTO with the tractor out of gear.

Most likely the 'black box' part that the safety switches feed into, and it makes the decision to kill power to the fuel solenoid (killing the engine just like you turned the key off) if the switches are in the wrong position safety wise.

A wiring diagram would be extremely helpful in this situation.

 

[ptsg]

It sure looks like a safety switch is acting up and messing everything up.

Have you tried making the seat switch operational again to see if something changes?

 

[tjstence]

Possibly the PTO switch is bad, but probably not since you can run the PTO with the tractor out of gear.

Most likely the 'black box' part that the safety switches feed into, and it makes the decision to kill power to the fuel solenoid (killing the engine just like you turned the key off) if the switches are in the wrong position safety wise.

A wiring diagram would be extremely helpful in this situation.

Absolutely agree with the wiring diagram. Unfortunately one was not included with this old tractor when I bought it. I'm on the look out for a copy online though!

 

[tjstence]

It sure looks like a safety switch is acting up and messing everything up.

Have you tried making the seat switch operational again to see if something changes?

I have not tried that yet. Didn't really want to mess with that part of it because I like it being bypassed, but I understand your point.

 

[Fuddy1952]

This may help. Looks like switches interface so over-riding seat switch may foul things up.
Wonder if you ask previous owner about it?

 

[pmsmechanic]

Just glancing over the wiring diagram. The seat switch has three positions. On - Off - Defeat. Make sure the seat switch is in the on position instead of defeat.

 

[zzvyb6]

Raise the seat and pull up the black switch post. This is the defeat position. Push the clutch in and pull up the pto lever. The tractor should stay running or if you didn't start it, you should hear the clunk of the fuel shutoff solenoid.

If the seat switch tip is broken off or the tab on the seat doesn't engage it, then the motor should quit and the fuel solenoid should release. I put a new seat on my 1070 whose seat pan is a slightly different shape. Same problem. The OEM seats are black. If yours is yellow, it's definitely a newer seat and a candidate for causing your problem.

 

[tjstence]

Raise the seat and pull up the black switch post. This is the defeat position. Push the clutch in and pull up the pto lever. The tractor should stay running or if you didn't start it, you should hear the clunk of the fuel shutoff solenoid.

If the seat switch tip is broken off or the tab on the seat doesn't engage it, then the motor should quit and the fuel solenoid should release. I put a new seat on my 1070 whose seat pan is a slightly different shape. Same problem. The OEM seats are black. If yours is yellow, it's definitely a newer seat and a candidate for causing your problem.

I think you're on to something here. I do have a newer yellow seat that doesn't seem to fit the tractor quite right. Thanks for the idea, I'll try out what you suggested today!

 

[tjstence]

I assume you are engaging the rear PTO. Do you have the same problem if you try it with the mid PTO?

My hunch is that a wire near one of the switches is grounding out to the chassis. My other thought is that the transmission switch is faulty. These 3 switches are only used to engage the starter. However, I've seen some Jeeps that had a transfer case switch that would short out to ground. If that were the problem with you unit, that would mess up the logic in your time delay module.

It would also be good to have your serial number, as there are two different wiring diagrams for the 1070.

My serial number is M01070A001151. Didn't know there are two different wiring diagrams, but I believe my tractor is an early generation 1070. Good idea on isolating the issue by trying the mid PTO, but unfortunately my 1070 doesn't have one. I know others do but I'm guessing it wasn't on the early generation models or it was just an option.