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Discussion Starter #1 (Edited)
I was in a thread the other night about a John Deere STX38 mower. I have one of these and I guess a regular problem with them is the starting problem that develops after a few years. It was mentioned, and I have heard in the past, that John Deere markets a "fix" for this problem, which costs somewhere from $15 to $35. The answer to my post indicates that the product from JD actually bypasses some safety features for a split second to get the starter turning, at least that's how I interpretted it.

Well, being the cheapskate that I am, I did a few minutes of research and found a diagram that, to the best of my calculations, does not bypass any safety features and ended up costing me $4.27 plus about 2 feet of wire and some connectors.

I put this right by the starter, as indicated in the picture, and is activated by the electrical impulse that normally gets the solenoid kicking in, which means that all safety switches have to be working (blade off, in neutral, etc.)

Guess that the JD STX38 isn't the only machine that his this problem. Various brands and engines, according to my research, are plagued with the "clicking" of the solenoid, making it necessary to turn the key many times prior to getting things rolling.

The dangling wire connector, with a white and black wire running to it, has always been there. It's not a product of my genius. May have been for a light kit.

Oh, by the way, I think that it actually works as intended. Throws the starter in first time every time!

I am not going to post a schematic on here. If you would like one, please drop me a PM with your e-mail address and I'll send it out. I have to make one up yet, but should only take a few minutes.
 

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Cool...My STX38 doesn't have the solenoid on the starter like that.....it is a separate unit under the seat....must have changed designs in mid run maybe....Mine is a black deck, 13 hp.
 

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Brad, how dare you "bypass" the JD parts counter! Just kidding, of course.
Excellent job applying a little independent thought and effort into the matter.
And thanks for sharing it with us.
 

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I have that same wire hanging and I think you're correct that it's for a light bar you can install in the hood I've seen on eBay.
 

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BTW, the official JD part somehow permits power to bypass the safety switches, but still requires the safety devices to be active and in their proper safe operation positions. Them thar's some hefty wire you used, Brad. The JD set has twelve gauge or thereabout.
 

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Discussion Starter #6
Yes, it's pretty hefty, but it was all I had around at the time. Plus, the one had an inline fuse. It was from some radios I had laying around here.
 

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Brad,
Good job on the backyard "starter improvement kit" as JD calls it.
 
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Discussion Starter #8
Of the 5 or 6 folks that asked for the schematic, have any of you put one on your machine yet? Just curious how it worked out. Whenever I get on my STX38 and get ready to turn the key, I am still a bit apprehensive until I turn it and away she goes.
 

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Kawas. have long suffered from this problem and we long ago connected a cheap off the rack starter solenoid ahead of the regular solenoid and used it to "fire" the original solenoid on Dixon mowers back to 1987.

All safety features remain 100% operational and it only takes 2 small jumpers.

Walt Conner
 

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Discussion Starter #11
Now I could very well be wrong, but with the component that I installed on my STX38, I don't think I am putting more amps to the starter, as nothing has changed with the starter itself. The only difference might be more amps to the solenoid, correct? That might be what you meant and I mis-interpretted.

I understand what causes this no-start situation is corrosion on all the safety contacts and wiring connections that forms over time, and that causes a drop (maybe) in the voltage to the solenoid. With the part I installed, the relay will activate with as little as 9v, and the voltage comes from the original wire that did run to the solenoid, so all the safety switches have to be functioning in order for an impulse to be present in the original circuit.
 

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Like so many others, I have been having the starting problem with my STX 38. Sometimes I would have to turn the ignition key on and off up to ten times to get the engine cranked. I checked the individual cells of the battery, and the charge was okay.

My first step was to replace the starter. Shortly thereafter, the problem returned. I then removed the negative battery connection, cleaned where it connects to the frame, and bolted it back into place. The problem continued. I then concluded that the problem must lie with the starter solenoid.

Yesterday I went by the John Deere dealer to purchase a solenoid. I asked for part AM104036, which the Deere website indicates is the correct solenoid. The parts clerk told me that part had been replaced by AM138497. I purchased the solenoid and installed it yesterday afternoon. So far, the starter has worked perfectly. (Incidentally, the original solenoid lists as 19.88; the replacement is $17.32. Would you believe that?)

I am wondering if there is some inherent weakness in the original solenoid, and Deere has addressed this by going to another part.

The solenoid on my STX 38 (black deck) is behind the battery, and it is not easy to access. The rear bolt which holds the solenoid to the frame is very difficult to remove.
 

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Just a brief followup to my previous post concerning changing out the starter solenoid on my STX 38.

Today I took apart the old solenoid to attempt to see if there were any obvious problems inside it. There was. There is a spring-loaded piece of metal which apparently completes the connection between the battery power input and the output to the starter when the switch is turned to start. The battery side of this metal piece was bright and shiny in appearance. The other side was blackened. The connection point where this piece makes contact with the body of the solenoid was also blackened. I suspect that this deteriorated contact point is what causes all the clicking when one tries to start the mower.

The problem could possibly be corrected by cleaning off these contact points. I didn't try this since I had already installed a new solenoid.
 

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" I suspect that this deteriorated contact point is what causes all the clicking when one tries to start the mower.
"

I suspect you are right, burnt because it was not making a solid enough "hit" when energized because deteriorated safety switches were not passing enough amperage.

Walt Conner
 

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Hi all,

First post here, but I've been in communication with Brad about the starting problem on the STX38. He was nice enough to provide me a schematic of his solution, and today I made it to the auto parts store to buy a relay, for $4 and change.

Well, I finished the mod today, and wow, the results were immediate and excellent. I can't believe it. I used to have to turn the key 10-12 times to get it to turn over. Now, first time, every time. Even my wife can start it now, whereas she would get frustrated and give up. Now I just need to get some tie wraps to clean it up, and away we go. Even the relay fits perfectly under the hood when it's closed, almost like it was meant to be there.

So Brad, a huge THANK YOU for figuring this out and for saving me about $25 for that J-D kit. This was so simple with your instructions, anyone should be able to do it with ease.
 

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Discussion Starter #16
Welcome, Androoos! Glad you jumped in and made your first post. The next 4000 will come in rapid succession, I assure you.

Now, when you get the ties on, how about shooting a couple of pictures and posting them?

Thanks for posting your results. Don't be a stranger. Drop in to the introduction section and post a bit about yourself and your machines. Be sure to check out all the other sections that MTF has to offer.

Glad the part made your mowing experience much more enjoyable. Glad to have helped.
 

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When I made my previous posts on the STX38 solenoid problems, I failed to mention one thing I noticed when I replaced the solenoid.

The replacement solenoid I got at the Deere dealer came with a large washer (about 1 1/2 inches wide) which is supposed to rest between the mower frame and the bracket which holds the solenoid in place. One of the two screws which attach the solenoid to the frame goes through this washer. The old solenoid did not have a washer like this.

The only purpose that I can see for this washer is to improve the quality of the connection between the solenoid and the mower frame. The original solenoid may have had a grounding issue.
 

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Hey, where was Brad when I was wasting my money buying the kit from JD? :00000060: :D Actually, Brad's definitely been a positive for this site. :trink39:
 

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Brad, thanks for sending me the schematic of your wiring. I am in the process of installing your fix. The one question that I have on it, is which wire is the wire coming from the key switch. I've looked and I'm not sure where the wire coming from the relay would attach to. You say connect the #86 (wire) connector "To Original Wire Coming from Key Switch". Where is this and how do I connect it? Thanks again and I appoligize for not thanking you before now.
 

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Discussion Starter #20
Thanks for the kind words, guys.

Tony43--The "original wire coming from the key" is a small wire that goes to the tab on the bottom of the solenoid. On mine it was a purple color, I think. If you look at the pictures I posted, see the red wire that goes to the solenoid? That is where the original wire connects. You take it off, connect a wire to the original, and connect one of the wires from the relay to the tab.
 
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