JD STX38 does nothing when I turn the key!

Lawnboy-man

Forum Newbie
Joined
Apr 20, 2020
Threads
2
Messages
8
Hello Fellow listers,
I own a 26 year old JD STX38. Up until last Thursday it started and ran great like it always does. Today I went to use it and when I inserted the key it did nothing. I usually get a click from the starter solinoid or the engine starts to spin right way. I have no idea why this would be happening any help will be greatly appreciated! Thank you all in advance.
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
55
Messages
14,681
Check the battery voltage first. Then check battery connections on the battery and where it grounds to the tractor. All must be clean and tight. Post back with results and we will give you more help.
 

Lawnboy-man

Forum Newbie
Joined
Apr 20, 2020
Threads
2
Messages
8
Check the battery voltage first. Then check battery connections on the battery and where it grounds to the tractor. All must be clean and tight. Post back with results and we will give you more help.
13.8 Volts coming off the battery. All connections at the battery are good and clean. The ground is tight.
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
55
Messages
14,681
Ok, then I would be using this troubleshooting procedure to identify the problem.

Electrical* problems can be very easy or very difficult, depending on four things.
1. * How well you understand basic electricity.
2. *What tools you have and know how to use.
3. *How well you follow directions.
4. *You don't overlook or assume anything and verify everything.

Remember we cannot see what you are doing. *You are our eyes, ears and fingers in solving this problem. *You must be as accurate as you can when you report back. *The two basic tools we will ask you to use are a test light and a multi-meter. *If you have an assistant when going through these tests it would be very helpful. *These steps work the best when done in order, so please don't jump around. *Now let's solve this problem.

First, check the fuse(s), check battery connections for corrosion (clean if necessary) and *voltage - above 12.5 volts should be good.*

Second, check for power from the battery to one of the large terminals on the solenoid. *One of the wires is connected directly to the battery and has power all the time so one of the large terminals should light a test light or show 12 volts on a meter at all times.*

Third, *check for power at the small terminal of the solenoid while depressing the clutch/brake pedal and holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. *If your solenoid is a three wire solenoid, make sure the solenoid body is not corroded where it bolts to the chassis of the mower as this is your ground path back to the battery. *If in doubt, remove the solenoid and clean the mounting area down to bare metal. *If there is no power to the small terminal then your problem is most likely a safety switch, ignition switch or in the wiring.*

Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position q(you may need an assistant to sit in the seat to override the safety switch).*

Fifth, check for power at the starter while holding the key in the start position (assistant again).*

Sixth, check your ground circuit back to the battery.

After you have gone through each of the above steps, let us know what happened when you did each step. *At that point we will have great info to tell you how to proceed. *Remember you are our eyes, ears, and fingers, so please be as accurate as possible.

Be as specific as possible with voltage readings as this will help diagnose your problem quicker. *If you do not know how to perform the above checks, just ask and I will try to guide you through it. *Youtube also has some videos and as you know a picture is worth a thousand words.
 

Lawnboy-man

Forum Newbie
Joined
Apr 20, 2020
Threads
2
Messages
8
Rivets, I went through your troubleshooting procedure in order only to find that the relay that I added to the starting circuit corroded and went bad. It really oxidized and I guess the internal workings went bad. I took all the wiring part and put it all back the way it can from JD. I sat in the seat and it started right up. The reason I put the relay in the starting circuit is because I have a clicking problem when I go to start the tractor sometimes. I put the key in the ignition, press in the brake/clutch and all I get is clicking from the solinoid. The relay lessened the clicking but did not get rid of the clicking all together. From what I understand from articles I have read on the internet that the clicking in these old tractors is cause by poor electricity due to old wiring. I have inspected all my wires and I did not find frayed wires or wire insulation that is rubbing off due to vibration. Do you have a solution for the clicking problem? As I have removed the battery and looked for a servicing hole for the transmission. Do you know if the transmission on this tractor can be serviced with gear oil? Anyway. Thank you for all your help and for your troubleshooting guide. It was most helpful.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
The prime culprit I find with old mowers is the battery leads.
None of them are sealed and they use interiour grade plain wire so water wicks down between the individual strands & corrodes through the wires.
When you ohm them they show no resistance but when required to take heavy current loads they fail.
And lets not forget bad ground connections as most solenoids ground through the case so the solenoid has to ground properly & the ground wire itself has to be good.
When I replace battery cables I paint each end liberally with stuff called "liquid electrical tape" after leaving them in the sun for several hours to heat up.
 

Richandtd

Member
Joined
Apr 5, 2018
Threads
8
Messages
34
On my STX38 same thing happened and the ignition key switch was at fault
 

Lawnboy-man

Forum Newbie
Joined
Apr 20, 2020
Threads
2
Messages
8
Thank you guys for the replies. The ignition switch is a few months old. I think I am going to replace the battery cables clean the attachment points at the solinoid and clean where the solinoid attaches to the body of the tractor and ground the solinoid well. I’ll let y’all know how it goes. Thanks again.
 

pooterguy

Forum Newbie
Joined
Aug 22, 2020
Threads
0
Messages
1
Both of my STX38 starter solenoids require an attitude adjustment with a rubber mallet while holding the key in the start position. I keep a mallet stowed on each mower and dedicated for this purpose.
 

Rivets

Lawn Royalty
Joined
Mar 11, 2012
Threads
55
Messages
14,681
Pooterguy, I would like you to do two things before offering advice on how to proceed. First, go through the troubleshooting procedure I posted. Second, after you have the results, start a new thread with the results and your units model and serial numbers, plus the engines model and serial numbers. With that information we will be able to make a better decision as to the direction you should go. Hyjacking another thread is frowned upon and will only get confusing for everyone.
 
Top