John Deere L120 mower won't engage while sitting on seat, raise off seat mower starts. Replaced seat switch and pto switch. Need help, thanks.

I would remove the PTO switch and have a Deere dealer test it. Also on the 500 series the PTO operates through the ignition control module which is under the dash, you can see it when you raise the hood. It is black and about 2" wide x 3" long and 1" thick.

Just out of curiosity check your pigtail that plugs into the pot harness. I have ran into a broken wire inside that pigtail before.

This sounds like a seat micro switch problem, make sure the block connecter is fully home and the switch depresses when you sit in the seat, if all else fails replace the switch

Probably the pto switch. Find the 2 wire 'T' plug from the PTO clutch and disconnect. With a voltmeter across the the 2 spades on the tractor side of the plug you should get 12 volts DC with the PTO switch on ( you may need to sit in the seat ). If you get 12 volts at the plug its probably the PTO clutch. If no power then its a fuse or the PTO switch

you have a bad seat switch

Park brake switch is the most likely culprit,any other would cause the tractor to not turn over in the crank position.

Try a new seat switch,or the rio switch on the right rear of the trans-axle.

sounds like the seat switch is bad

CK THE SEAT SWICH OR THE BRAKE SWICH ONE OFEM IS BAD

have a john deere zero turn that will not turn all the way over