JD LT155 Lawn tractor with Kohler engine wont turn off.

   / JD LT155 Lawn tractor with Kohler engine wont turn off. #1  

duggie

Member
Joined
Jun 4, 2012
Messages
39
Location
Queensland
Tractor
Ford 3000 McCormick A414
The LT155 I use here has been performing well and I have replaced the deck twice and needed to replace the key switch once.
I now wish to fix the current problem I have in that the engine wont turn off. I have to pull the plug lead.
Its the 3 position key model with the 3 amp charge.
I found a great manual on line with circuit diagrams etc and troubleshooting guide but it does not help much.
I have found a white wire that goes to the magneto that controls all the engine stop functions such as getting off the seat while the blades are going etc. It says both sides of the magneto are earthed to stop the engine. One side is earthed anyway and the other white wire if earthed by any of the several relays will stop the engine as well.
Well I turn off the key. Engine still runs. Run a jumper from the white wire at the engine cowl to earth. Still runs. I cut the bloody wire. Still runs.
I unplug the whole wiring loom going to the engine. Still runs.
How can this spark ignited engine keep running with no source of power?
What do I do next?
All help appreciated.
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off. #2  
If you are grounding the kill terminal at the coil and it doesn't die it needs a coil.
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off. #3  
The engine makes its own power thru the coil, does not need wire to ground. I bet if you ground out both sides of the cut white wire it will stop. The switch may be defective, so its not grounding out the wire to stop motor.
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off.
  • Thread Starter
#4  
OK you both seem to say it makes its own power. Must be true as I grounded both ends of the white lead. Still ran on. Disconnected the battery completely. Still ran on.
So to fix this I gather I have to pull the cover off the engine and look at the Magneto.
Is it all one part or is the coil I need to replace separate?
Thanks
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off. #5  
The coil is all self contained. SO if you are not dealing with a terminal issue or a broken wire, it would need a coil. Verify that the ignition switch does not send power to this terminal at any time.
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off. #6  
The coil produces spark each time flywheel magnet passes underneath the mag.
grounding this spark is the way to kill the motor. (Another way is a stop fuel solenoid, not sure if yours has that). So whatever means that unit has to ground this wire is the issue. I dont think the mag needs to be replaced. I think the issue is either key switch or wire that grounds out mag.
can you find a wiring schematic
 
   / JD LT155 Lawn tractor with Kohler engine wont turn off.
  • Thread Starter
#8  
Thanks. I have the same wiring diagram as the link. As indicated the white wire to the coil , if earthed should cut it off. I earthed it directly where it goes into the engine so bypassing all the relays and kill switches etc. It should have stopped the engine but did not. I wonder if the wire is broken under the engine cowl somewhere but not shorting out. If its broken then me earthing it wont have any affect. I guess its time to pull it to pieces.
 
 
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