Manage My Life

John Deere L120 Lawn Mower will not engage blades.

by Manage My Life Last activity date:
May 15th, 2012

Was cutting grass and then noticed that blades were not turning and cutting grass. The lawn mower blades will not engage when PTO switch is pulled up. I bought a new switch for the seat and replaced it, but that did not resolve the problem. I disconnected the PTO switch and checked resistence on the pins. The pins are in three rows labeled Com A, Com B, and Com C. When I checked these pins Com A and Com B was reading around 1.0 ohms. Com C has been getting very erattic readings 22.0 ohms and higher at times. Thinking it may possibly be the PTO switch. Another thing that is unusual, is after replacing the seat switch, I tested the seat switch to see if mower would turn off if I got off of the seat. The mower kept running after I got of the seat, and I did not have the parking brake engaged. The mower should have shut down if I am not mistaken. Not sure what to do right now.

Lawn Mowers
Be the first to comment
Ask your friends
Answers (5)
Jerry C
Hello Michael,

First of all, I appreciate the troubleshooting that you have already performed. I can verify that you should not be seeing erratic ohm readings on any of the connections at the pto switch. The switches in the circuit are either open or closed and the solenoids should show a steady ohm reading. The 22 ohms that you read would be typical of this type of solenoid.


is a link that I was able to find to the actual wiring diagram for your tractor.

If you would determine what color wiring is at the contacts that you mentioned as A, B and C, I would be happy to assist you in determining where the fault is. I would say at this point it is a connection issue of some sort, wiring or internal to a switch or solenoid.

The seat safety switch is a good indicator that there is probably a damaged area in the wiring harness itself or one of the switches in the circuit has failed. However, you may want to check to be certain that the switch hasn't been inadvertently depressed in it's housing.

I look forward to assisting you with this problem.

Jerry C
by Jerry C
May 15th, 2012
| Be the first to comment
0 votes
To view more answers
Join Now
Add your own answer
Sign in to answer a question
Didn't find what you are looking for? Ask a question