JD Z925A ignition switch problems

[KE4AVB]

Anyone been having the following problem?

Engine won't engage starter. If jumped at the starter solenoid trigger wire it starts. On board diagnostics indicates bad ignition switch. I had this a couple times with this ZTR. It been in the JD shop nurmerous time for the same problem. What I have found is switch is only partially shorting the start circuit (around 200Kohms or less) but the on board is thinking a completely shorted out. This is start contacts that is showing this resistance when when the switch is in the run position. If this resistance is more than 200K the computer no longer sees a problem.

Is there an additive that I can put in the switch to remove and keep the moisture out? The customer has already tried WD-40. The switch is somewhat weather resistance but apparently not completely. The switch installed is the one JD sells.

[bgsengine]

With your electronics background I would think you would have thought to wire in an extra resistor or two into the circuit?

[KE4AVB]

With your electronics background I would think you would have thought to wire in an extra resistor or two into the circuit?

Yes I have thought of that too but I was hoping someone have resolved this before I go through a lot experimentation. I could drag out that decade box but it still buried in those storage boxes from the move.

It would be nice if I had a circuit diagram to work from but those are harder to come by for the JDs. Maybe I see if Jay @ JD can provide me with one; I will go by in the morning and see.

I simply don't know how this JD computer is scanning the the switch; otherwords, is the circuit triggering via a pull-up or a pull down resistor. I have seen it done both ways over the years on other systems.

[KE4AVB]

I think I got this figured out in my head just got to get the mower back to try a couple things. I plenty resistors left over from years ago. I think they are using an AND or NAND gate circuit and they left the inputs floating.

[Arkie]

And good luck with locating your stuff after the move.

I was in same location for 40 years and recently moved and tried to store stuff in logical order, mechanical, electronics, electrical, wood working tools, small engine parts and pieces and spare and repair stuff (wife calls it all junk) in a 80x80 shop and a 36x24 shop and a garage and I took about year to move,labeling boxes and building storage shelves, storage pod 12x24, work tables, work benchs, pegboard hangers for tools, welding stuff, refrigeration tools, and few times I've had to simply give up looking for something, make myself a note to watch out for it, and sure enough might be couple weeks later I'll run across the misplaced item while looking for something else. Really is a head scratcher when you know it's around somewhere, but not where it was suppose to be.
In a previous move 40 years befoe the rear doors came open on a moving van and lots of stuff scattered along the road and later I would go buy a tool or parts thinking it was lost and then run across the stuff that was not lost on road later usually day or two after buying new stuff.
Moving is a pain especially when you need to keep in touch with your stuff.

Good luck to ya!

I've had to tell the owners of eq to cover their eq or store inside to keep outside elements from ruining stuff, especially key operated ignition switches. If they don't, pay me now and again later. Sometimes moisture even ruins the mating slip on ignition switch plug. I've found tractor transmissions frozen and full of water from being left outside.

[KE4AVB]

Wish I had the funds to build a 80 x 80 shop but the 24 x 24 shop will have to do for now but will add on to it later. I went from a 28 x28 workshop and a 24 x48 storage building so everything jammed up in that one shop now. A lots things had to be left behind that were not as important as the business stuff.

I do have storage building to repair. It had some tornado damage roof tin and who ever repair at it had no idea how to roof. They put the replacement tin on backwards and resulting water damage has destroyed roof supporting structure. I would be afraid to let anyone local to do repairs for me based what I have seen so far. It will need to be completely stripped down and rebuilt before I can store anything safely in it and it would make a nice radio shack. I did manage redo the roof on temporary basis and the inside as dried out but it too late to save the main upper structure as it was insulated.

I know how you feel about the misplaced tools and parts; just found a drill that I replaced last fall. Got stored in the wrong box during that 3 week move I had to do. I also still finding things that were misplaced before the move as I packed away things before the move as I expected I might need to move; brother was really showing his backside. Maybe I find of rest of the stuff as the rest gets unpack in a few months.

As for the JD I thinking is just poorly buffered electronics. It is the off season so maybe the owner is just dragging his feet about returning the equipment but you know we can't work on things if it not accessible. He was to bring it back in last week. It also been below freezing the past week. Boy I hate sudden temperature changes with the roller coaster we are on now 50-60 in the day and down to 20 or less at night. Afternoons is about the only time I can work outdoors without needing shock absorbers for my knees and teeth. Just can't get adjusted to the temperate swings. Boy I miss my heated shop.

I found my electronics test equipment just don't know if I put it all in two large boxes but I going to build a test circuit to see if my theory is valid.

[KE4AVB]

I am just going to close this thread out as the customer has not returned.

I did mange to build a test circuit testing the pull down resistor theory and it should work and had only a 6 mirco amp current draw when switch assuming a 200K ohm contact resistance leakage so that should not be any noticeable battery drain when not in use. Just depends on how JD is detecting the switch operation via the computer.