There will also be a safety switch on the brake pedal. I think you are on the right track with the safety switches...your symptoms sound just like a faulty safety switch. You can test your saftey switched with a multimeter set to test for continuity. The two blades on your switch should show zero continuity, or Open Line (OL) until you push the plunger and you should have continuity. If you don't have continuity at those two blades with that plunger pushed in, then your switch is bad. Check that brake pedal switch and let me know what you find.
Ok, take a look at this diagram. Ref # XXXXX in the diagram is identified as a brake switch and #54 is a brake switch connector. If you've bypassed both your seat switch and your neutral start switch(#33), then try testing for continuity, or bypassing the brake switch.
try that and let me know what you find.
The diagram does not provide that information, and I doubt if bubba or jim bob at the local dealership here in my town could tell me either. Your brake pedal arm is physically pushing that plunger in to engage the switch. See if you can follow the brake pedal arm to find it. You'll want to avoid doing this if possible, but removing the mower deck(if applied) may make finding that switch a little easier. Also, jacking the front end up in the air will make it easier as well. I think if you did have a color coding to work with, you'd find once you get to a connector, the corresponding wire would change colors on you anyway...not always the case, but often find that they;ll change wire coating colors that meet at a connector. Follow that brake arm and you'll find that switch.
I looked up the JD model you provided. The diagram in question is for your model 318 JD. Let me know, thanks,
My experience in the past with seat switches on JD mowers is that they are typically harder to bypass due to sometimes having more than two prongs and wires to deal with. You might try replacing that seat switch. Your problem is SO typical of a saftety switch that I am having a hard time thinking of anything else that would make it behave the way it is. Try a new seat switch, and if that doesn't work for you, let me know and I'll opt out of your question and open it up to other experts here on Justanswer that may be better educated on this than I. Let me know how it goes.
Ok, I follow you, but I am at a loss myself so I am going to opt out of your question and open it up for other experts to take a stab at...they will have access to all of the posts you and I have had up to now, so they'll be up to speed on what we've tried already. I'm sorry I couldn't help, and I hope one of the other experts here on Justanswer will be able to nail your issue down.
I am Still betting on a bad seat switch or a wire to the seat switch.
Humor me.. Test the seat switch with a meter. Is there current when the seat switch is pressed? IS there no current when the switch is not presses.
Correct me if I am wrong, but is the switch not supposed to be OPEN when pressed and shorted when the switch is not pressed. If this is the case, then shorting the wires to it would be mimicking having someone off the seat? Therefore making it not work?
I have not had much sleep, but could be backwards.
Unless I am very mistaken about your circuit configuration, it would do just the opposite. Closing the switch would complete the potential path to ground, so it would be the equivalent of never being in the seat. Once the blades are engaged, the ignition coil would ground out and cause the engine to die, which is what I understand is happening. You want to "open" the seat switch rather than "close" it to test it. You want to prevent the circuit from reaching ground through that path.
As I said, I may be wrong since I'm not a John Deere guy, and they're pretty protective about their info. The ones I'm familiar with use the seat switch to ground. Here's a schematic that will show what I'm talking about. Your's may be different. As I said, I'd sure like to see the schematic to know for sure.
You can see in this one that the seat switch normally is closed and provides a potential path to ground that is completed when the PTO is engaged (follow the path of the yellow wire from the armature). When the seat is occupied, the switch will open and break that path so the PTO can be engaged and the engine still run. Some wiring harnesses I've seen will be built with shorting clips that come together if the switch is removed to defeat the possibility of a user just pulling the switch out. If yours works like this you will need to open, not close it.
You are right the seat switch wires need to be wired together to bypass the switch. When did this problem start? With the tractor not running turn the key to the run position and engage the pto switch. Does the light go out? Can you hear the pto engage? What module did you replace (part number)? What is the serial number of the tractor and does it have single or dual pto.
Sorry i retired last night before you got back to me. The pto light being on and engine shutting off sound like to different problems. First lets try and fix the shutting off part. You should have to fuses one with pink wires and one with red wires. Check the one with red wires for bad fuse, melted holder, and corrosion. If that looks good turn the key to the on position and check these points for voltage with back wire of tester connected to a good ground. At key switch, red wire going to fuse. At module plug, prong with one red wire and one pink wire. Seat switch wires. At module plug, single pink wire. Let me know were you have voltage. And are all the connectors and plugs still original.
I will wait till i you get back to me.
Test results are a little odd since you have power at each end of the circuit but not in the middle. But maybe it can back feed through the module so unplug the module and redo tests. It looks like it might be a bad fuse box or the red wire that runs from the fuse box to the module plug (red and pink wire) is pinch off somewhere. If tests are the same except no power at pink wire take a safety pin or something and poke it through the wire about a inch or so back from the fuse box and check pin for power. Do it to both wires from fuse box if you do not have power on both wires the fuse box is bad. Let me know what you find.
Hope everything works for you. Let me know.
P.S. If you are satisfied with my help please hit the accept button so i get paid for my time. Thanks