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First of all, it's with the blessing of the moderators that are assigned to this section that I am posting and sticking this thread.

I have a John Deere STX38 that has been plagued with the starting problem that seems to be inherent to that machine. You turn the key, and you get the good old "click" from the solenoid. A small smack on the starter with a nearby tool (screwdriver handle, hammer, spade, etc.) would generally make the starter engage and turn over. I tore the starter apart several times, cleaning, lubing, etc. trying to find/fix the problem, to no avail. Then, somewhere, I read a post about the availability of a "Starter Assist Relay" that was sold by John Deere to fix this problem. Price was somewhere in the neighborhood of $25. Well, that was a bit steep for me so I went about searching for a less expensive alternative. I found a post on another forum telling of fabricating a similar item for Volkswagon automobiles with the same issue. I decided to try and build my own. Subsequent to my original post in the John Deere section, others have approached me for a copy of my schematic for different models of John Deere and different brands of machines. The cause of this situation is that over time the different safety relays get corroded, connections get corroded, batteries are still good but put out less than optimal voltage. This alteration does not in any way bypass any of the safety switches on your machine. If you could not start your tractor because of a safety issue prior to installation of this relay, you still will not be able to start it.

Well, the first thing in this project that I needed was a relay. Plain, old relay. The kind that every auto on the road has 6 or 8 of. I went to a name brand auto parts store, with the design of the relay drawn out on a sticky note, so I could tell them what I needed. When I walked in and told them what I was looking for, so I could build a project for my lawn mower, I got the old "Deer (not Deere) in the headlights look".

"I don't think we carry lawnmower parts like that."

No, I said, I need an auto relay, it's for a project I am building for my lawnmower.

"Here's all our lawnmower parts. See, we just carry spark plugs."

No, let's start over. Do you sell auto relays, like for horns, lights, fog lamps, etc?

"What kind of vehicle?"

It doesn't matter!

"Well, we sell trailer light kits for about $25 over here."

We go over there and he shows me the light kits. Right next to it was a relay just like what I wanted for $3.95ish. I'll take this. It's just what I need.

"Do you think that will work in a lawnmower?"

Anyway, I take my purchase home and begin my assembly. First thing I notice is my shortage of different colors of wire. I thought about going back to the auto store, but I am pretty sure they didn't sell "Lawnmower wire" there, so I compromised. I cut 4 lengths of wire about a foot long each. Put some female spade connectors on 1 end of each wire, attached them to the relay. Then, I read my directions and compared them to the info on the back of the relay package and figured out my next step. I labeled all the wires (ground, 12v, key, solenoid) and started my installation.

I don't know about you, but whenever I work on something and it's time to give it the old "college try", I am a bit nervous about the outcome. I always dread that my work was for naught, and when I prepare to see if I made any difference in my machines operation I always fear the worst. Well, I plop myself right down on the seat, make sure that the PTO switch is off--check, in neutral--check, turn the key--NOTHING. Oh, I forgot to re-attach the battery. Fixed that, let's try it again. Sweaty hand reaches down to the key turn it to the "START" position, and bingo! Turns right over! Oh, well, that had to be a fluke. It was just luck. Gotta try it again, just to be safe. Sure enough, turn the key and away she goes. Oh, boy. I gotta get some pictures of this and post 'em on MTF. This is really gonna be a hit! And, it appears, it was a hit. I have had many requests for this schematic since the original post and about everyone reported a success after installation except 1 fellow, and I think that he did figure out the problem. So, here is the schematic for the starter relay, along with a link to my original post, in case you have any questions. If you click on the relay, you'll get a larger image that you can print out. If you have any problems or need further info, just PM me or drop an e-mail and I'll see what I can do to help you out. Have fun, and be sure to report your results!

Thanks to member Wayhaw, I have a .doc file that will help a few folks with better descriptions and explanations. Let me know if you need a copy of this. Please include your e-mail address.

Original Post--Click Here
 

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I get the same looks and reactions from needing "dirt bike parts". I now just say I need so and so part and don't even say what it's for.
BUT most bearing shops will not do this to you. You can tell them it's for a dirt bike and as long as you know what bearing you want(or have the old one in-hand) they will hand a new one to you in a matter of seconds.
Good work.
Wonder if that will work on a Murray lawn tractor? They do the same thing.
 

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Discussion Starter #3
Wonder if that will work on a Murray lawn tractor? They do the same thing.
Should be just fine, Diesel_Nut. Here is the concept of the relay:

When you turn the key on your ignition, the current needs to go thru, generally, a couple of pressure switches, some terminal blocks, wire connections, etc. By the time the voltage gets to the solenoid, it has dropped from the optimum 13.5v or so down to maybe 10-11, enough to make to solenoid "click" but not engage.

After you install the relay, when you turn the ignition it does the same thing, but when the 10-11v hits the relay, it gets activated, which in turn makes a complete circuit from where you tap into the heavy 12V line that runs to the solenoid, then gives the solenoid a good solid voltage into the small terminal, thus making a good circuit to activate the solenoid and subsequently the starter. It only takes about 6-9v running into the relay to activate it.
 

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I used the same relays for my lights and PTO clutch. Originally the ignition switch had to carry the whole load and would overheat the terminal at the switch, now the switch stays cool.
 

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That's a good idea, Butchs Hobby. Any chance you could post some pictures and tell how you did it?
 

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Same relay, wired the same as your pic except the wire you say to key switch goes to the switch of whatever you want turned on and the wire you have labeled to solenoid goes to what you're turning on. For my 12 volt source I used the factory circuit breaker, that way everything is still protected.
 

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I performed a similar modification that I documented on the Cub Cadet forum. There are pics there as well as a part number for a Dorman relay (under $8.00) that is available from most any auto parts store. See http://www.mytractorforum.com/showthread.php?t=105727. HINT: apparently a lot of guys that install power sucking amplifiers in their trunks use them to power their boom box vehicles.

This concept makes so much sense that you would think that the manufacturers would incorporate it in their new models. Then again, it would cost them a couple of bucks and they never have to screw around with their tractors once they have left the shiny new condition of the show room so they probably don't even know or care that this problem exists.

JN
 

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Discussion Starter #8
I looked at your original post. Nice job of describing and fixing the issue. Thanks!
 

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It made a big difference for me. I Have talked to a number of people that have encountered similar starting issues with their tractors so I know it is a very common problem. Hard to imagine that the manufactures have not addressed this situation on new models - especially since it does not in any way defeat the safety features built into the tractor(s). It is clearly a problem that spans many makes and models.

JN
 

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I had an issue with my JD Hydro 185 a few months after getting a new starter solenoid. It worked for a few months, then it worked sometimes, then not at all. Instead of replacing the solenoid again, I just use a screwdriver to jump it....works great!
 

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I just replaced a solenoid on my generator yesterday, couldn't believe it when I went to start it and it wouldn't fire up....

I couldn't resist taking it apart to see what inside goes bad... On mine one of the coils soldered leads had broken free.

Inside there is a springed copper strap about 3/8 X 3/4 long that has a plastic insulating rod fastened to it's middle.... it slips into the coil's metal plunger.

When the coil is energised the plunger comes out and forces the copper strap downward making contact with the two 10 MM studs that carry the volts and amps to the starter.

I'm guessing it's high resiantace at the solonoids contact points caused by a small amount of arching each time the starter is used. There are no condensers to help with arching.
 

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Brad--that's very informative--and do-able for A lot of folks..

Thanks for the imput, and I have a good friend that I work around stuff like this on--he's really a soundingh board and quick to point out faults..

Glad to see ur tech exchange badge by your name....:thThumbsU

glenn
 

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thanks brad and bosox now time to get serious. hope i don't fry anything. going to try new selenoid and ignition module first. i can jump accross selenoid and get it running. put key in run position and runs but stalls after a couple of minutes. hmmm is that related? oh well parts come in today keep posted kw
 
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