Lawn tractors with failing or broken ignition switches cannot start the engine because no electrical connection is made between the solenoid and the flywheel in the starter. The ignition switch not only sends power to the starter which turns the engine over, it also makes an electrical connection that sends power to the lights. If you have a lawn tractor with a bad ignition switch, you can replace it yourself without having to take it to a small engine service repair shop.
Things You'll Need
Replacement ignition switch
Set your lawn tractor's parking brake to the "On" position and take the key out of the ignition, if you have not already done so.
Open the hood on your lawn tractor to expose the back of the ignition switch; there will be a harness connected to the back of the switch.
Unplug the wiring harness by hand or use pliers to gently disconnect the wiring harness from the back of the ignition switch.
Remove the retaining ring from the front of the ignition switch by twisting it off with pliers. The ignition switch should now be loose, but not free from the operation panel.
Push the retaining tabs on either side of the back of the ignition switch with a flat-head screwdriver, then push the ignition switch out through the front of the operation panel.
Insert the replacement switch through the front of the operation panel, popping the retaining tabs into place. Reconnect the retaining ring on the front of the switch and tighten it with pliers.
Plug the wiring harness back in to the back side of the replacement switch. Close the hood on your lawn tractor, insert the key and turn the ignition over.