STX38 electrical issues

tim2 · Apr 17, 2016

Yes I have jumped the solenoid, two large posts and got nothing. There is no power cgoing to the side of the solenoid that is wired to the starter. Yesterday I replaced the solenoid with a new one and got nothing when I tried to start the mower, then I replaced the key switch still nothing. I then jumped the seat and brake safety switches and again no power to the starter. I checked every wire for a fusible link or a fuse and have found none at all.
I am going to test to see if the key switch is getting power today, hopefully it is as it was working (cutting grass) about a week ago. If I find the key to have power CAN I unhook and jump the two wires going to the PTO Clutch and try to start the mower? Or will this damage the pto clutch.

bertsmobile1 · Apr 17, 2016

So you bridged the two large terminals and the starter did not turn.
OK, Now we are getting somewhere as we are understanding each other.
To test the solenoid, dissconnect the two control wires. Run power to one and earth out the other,
You should get a loud click.
If that is the case run your heavy jumper to the starter terminal post on the solenoid.
Motor turns = starter feed wire is OK motor does not turn, lead is faulty.
Move the heavy jumper to the battery side of the solenoid and use the small jumpers to energise the solenoid as per before.
Starter turns = solenoid OK and the main power wire from the battery to the solenoid is faulty.
Leave the heavy jumper on the battery side terminal, reconnect the two control wires to the solenoid and try the key.
Starter turns = wiring & safetys are OK
Starter doesn not turn = another problem in the wiring.
Naturally brake on PTO off.

tim2 · Apr 17, 2016

OKay I think I understand whate you are saying. The two control wires you refer to are the small wires on the bottom of the solenoid correct? It really has my mind spinning because the owner was cutting grass when the old PTO clutch burned up. Seems to me that it is the new clutch that is faulty and not making connection when I attempt to start the mower. Going to follow your last two post and once done I will connect 12v dirrectly to the clutch to see if if functions at all. Thanks for hanging in there with me. I will post results once the sun comes over the horizon.

tim2 · Apr 17, 2016

Bert, I just tested to see if there is power at the key switch, and yes there is power going to the switch. I then removed the two small wires on the solenoid and ran jumper wires to the terminals, one ground and one power. I did not get a loud click the motor actually turned over. I checked continuity of the positive wire from the battery to the solenoid and it gave a reading of 0.03 ohms which tells me it is okay. I then plugged the small purple wire back onto the solenoid and left the other hooked to a ground, reinstalled the key switch and got no noise from either the solenoid or the starter.

tim2 · Apr 17, 2016

I just thought of something else to test. The old PTO was liquid welded back togetrher and when it broke if locked the motor to the point it could not be turned over with an imp-act gun. What is the possiblity that it also burned one of the electrical wires running to it? HMMMMMM might have to get out the multimeter again.

tim2 · Apr 17, 2016

Continuity tested great. Back to square one, haven't anthing that is keeping it from turning over..........

NorthBama · Apr 17, 2016

haven't read all the post just jumping in. Please excuse me for just jumping in but you may want to check the PTO switch with an ohm meter and make sure the contacts open and close. I have had the pto clutch to go and it takes the pto switch with it.

tim2 · Apr 17, 2016

I tested the PTO switch and it is good. The mower was running when the old PTO clutch went out.

bertsmobile1 · Apr 17, 2016

Again for the purpose of clarity.
The control wires are purple and black.
If this is the case you should see 12V at the purple wire when you turn the key switch to start.
You should also get continuity to earth on the black wire when you turn the key switch to start.
If no 12V follow the purple wire back .
It should go to the brake switch then to the PTO switch then to the key switch.
Generally it changes colour at every switch just to confuse you.

If the black wire has no continuity to earth then you are looking at one of the relays

tim2 · Apr 18, 2016

I poked around for a little while on it yesterday and came up with nothing new. I will check your last tip today, I have an appointment this morning so it will be later today. I have not seen any signs of relays, it appears everything is just straight wired with no relays, fuses or fusible links. Anyone have a wiring diagram for this STX38 or ideas where the relays and fusible links are?
Bert, the purple wire from the solenoid goes directly to the PTO clutch and the other wire goes back to the PTO switch. I will post back what I find today.

STX38 electrical issues

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