JD4100 engine stalls after engaging PTO

henksoer · Jul 28, 2015

The engine of my JD4100 HST stalls after engaging the PTO switch in all 3 positions of the PTO selector handle, even without load.
Since the PTO-solonoid works OK I suppose the hydraulic PTO brake doesn't release.
After a week the problem resolved without any reason
Does anyone know what's the problem?

JD5210 · Jul 28, 2015

Do you have a wiring diagram? A quick read of the operators manual says the -PTO interface Engine shut-off solenoid de-energize in 1/2 second, causing the engine to stop if operator off the seat. - Granted there would be other problems if the seat switch was bad, but a wiring somewhere coming loose could be the problem.

henksoer · Jul 28, 2015

Thank you! I will check. I have a Technical Manual with a wiring diagram, so there's some homework to do.

JD5210 · Jul 28, 2015

If you need help with the wiring diagram, attach it as a .pdf and I maybe able to help you. Looking at JDparts, there is a relay part number M808087 the remarks say it is PTO INDICATOR LAMP (SAFETY RELAY). The word safety relay caught my attention, I would check this relay, your tech manual may have a write-up how to test the relay, if you think that could be the problem.

henksoer · Jul 30, 2015

I think there are 2 possibilities: The PTO brake doesn't release. In this case JD recommends to check the brake piston O-rings, or there is an electric shut off with a delay of 0.5 sec. caused by a faulty seat-switch or maybe a faulty control module. But in case of a faulty seat switch I think the engine would not even start. Because the engine-stalling sounds more like smother then a normal key-shut-off, I suspect the PTO-brake. But I gladly swap my opinion for a better one.
See the wiring diagram in attachment.View attachment JD4100HST wiring diagram.pdf
Diagnoses:
View attachment Tm1630 4100 TEST SEAT SWITCH.pdf
View attachment Tm1630 4100 CONTROL MODULE.pdf
View attachment Tm1630 4100 ENGINE SHUTTOFF.pdf
View attachment Tm1630 4100 TEST RELAY parkbrake safety PTO-light.pdf

JD5210 · Jul 30, 2015

I agree the seat switch most likely is NOT the problem as you would have other problems. You may be right that the PTO brake is the problem. I would think it would sound more like the engine is being dragged down like what you might hear when you put it under a load or going up hill.

One think you may consider is putting a voltmeter on the fuel shutoff solenoid to see, if you lose power to it, this may not be easy as there are 3 wires inside a plug and there is 2 coils most likely one is for the initial start coil and the other the hold coil after starting. I would think the tech manual might give some help here.