JD 4100 1998 vintage

[parrot24]

Ok here goes I have a John Deere 4100.
Starts fine runs well does it's job. All is well until I stop with the tractor running put it in neutral
get off the tractor with it running get back on after a couple minutes go to put it in gear stall's starts back up put it in gear
it want's to stall forward or reverse. Check the idiot switches and all seem well it drives me nut's. If I keep working no problem
it's only if I stop get off to rake stuff into bucket get back on same problem.
What the hell do I look for? PTO also want's to cut out. Foot on clutch brake on. Ass in seat.
Please help I'm at my wit's end.
Tractor can be cold or hot don't matter all outside temp's.

 

[al3]

Said you checked the safety interlock switches----did you pull them off and test with an Ohm meter? Or what?

First thoughts reading your post is one of the various interlock switches slightly worn and/or out of adjustment. Seat would be the first thing I'd check. If the gear models have an interlock associated with the gear position, that'd be the second.

Does your model have a seat bypass switch that can be pulled? Designed so the pto can be operated without anyone in the seat.

 

[GaryM]

I have the same model one year newer. There is a switch under the seat. Fold the seat forward and pull up on the switch.

 

[parrot24]

Hi, I do have a gear drive and a switch under the seat. I have pushed it down pulled it up in the up position it seems to work but can't leave it up there is a bar that you can lift to keep the seat from tripping the switch when no operator is in the seat. I haven't tested the switches with an ohm meter there is one under on the left side of the trans. but you would have to take half the tractor apart to get to it. I have unplugged it and plugged it back in but its a b*&%$ to get at. There is a blue wire coming off the starter that at one time I traced and unplugged it plugged back in it seemed to work for awhile but then back to the same. This last time last week I pulled the under seat switch up and back down was alright for the rest of the day. But that doesn't alway's work. The switch I'm looking at is on the trans. under the shift mechanism's that's the one I've unplugged and plugged back in it doesn't help. I don't know if it is sticking or not.

Thanks for all the input I'll keep checking.

Please keep the input coming I'm alway's open to suggestions and ideas.

 

[al3]

I have the 4110/4115 shop manual. Assuming nothing changed between the 4100 and this, then the following might be of some use.

Read the logic description of the safety circuits. To rehash, there are several components (seat, transmission and PTO switches, safety module, a diode, a few relays, and then the fuel solenoid. A couple of pages of various test. Sorry I don’t have access to a scanner at the moment.


What stands out are your failure modes, When you get off/on you are weighting/unweighting the driver’s seat (switch 1) and shifting from neutral into gear (switch 2). Switch two is normally closed when in neutral, open when in gear. From the tech description, switch 2 only come into play only at start up. (It allows a secondary coil in the fuel solenoid to be active for 5 seconds enabling it to pull in. After 5 seconds, and the solenoid plunger has pulled, the primary coil stays active enabling the engine to run).

Description says that if all other components are operating correctly, it’s only the seat switch that interrupts the primary coil (via the control unit). You are supposed to have a 10 second grace period where the seat can become unloaded (with the tractor in gear or the PTO engaged) before voltage is cut to the primary fuel solenoid stopping the tractor.

The tractor running when you get off, but only quits once you get back on AND SHIFT INTO Gear points to the seat switch or the control unit (which is also physically located under the seat bracketry). Also believe, not sure, that you said the PTO cuts out from time to time, presumably with your tail in the seat. Manual states the same logic. Sensing no operator (seat switch) the control module stops the current flow to the fuel Solenoid.

You should be able to check the seat switch while it’s installed. Disconnect the plastic connectors. With no pressure on the switch, no continuity between any of the four spades. With the switch down, the red/yellow and red/white wires should have continuity. With the switch pulled up, continuity between the blue/black and white/black wires. I’d wiggle the switch when doing the test to see if you get a sporadic reading.

If the switch checks out, maybe examine the connectors/wiring for chaffs/shorts/loose bad connections. Dig a little deeper under the seat and you’ll find the control module. Check the connectors, see if the thing smells like burning brake shoes.

You could also rig up a temporary bypass switch to the fuel solenoid---I had one for awhile when my control module went south. Gets a little tricky, but a good way to try to isolate an error condition.

All guesses, I wish you luck.

 

[parrot24]

Hey Thanks I'll check it out. I think I have a service manual on disc.
I don't know if it's service or parts I'll have to look.
Thanx again.