Weird sensor problem, any ideas? John Deere L120 riding lawn mower

[cjstroh]

Hi all, I have an old John Deere L120 riding lawn mower that I have been maintaining, but recently I have been stumped by a tricky issue, and I am hoping for some suggestions on what to try next. Thanks in advance for any help you can provide.



My mower runs fine, but the engine stalls out anytime I do two different things. Both problems appeared at the same time, after stopping the mower long enough to talk to my daughter.

1. Engaging the blades: when I pull the knob to engage the blades, the engine stall out like a safety sensor is killing it.
2. Reversing: I can reverse fine, but if I push the reverse RIO button while I’m reversing, it stalls out like a safety sensor is killing it. This is when the blades are *not*engaged, so it lets me reverse without pushing the safety button as usual. But, if I push the RIO button it stalls out as if I was reversing with the blades on, and not pushing the button. Weird.

Here’s what I have tried:

Replaced the seat sensor switch and brake safety switch. Both seem to be working properly.

Tested both the RIO (reverse safety) button and the PTO (blade engage) switch. Both show proper continuity when on and off.



It seems to be getting a signal to stall out even though I can’t figure out where the signal is coming from. Any suggestions for what to try next?

 

[StarTech]

You probably just unplugged the seat to test it. What I suspect is the seat switch connector has a failed shorting strip. If this is the case then the switch is being out as if no one is in the seat. Can be shorting just one of the two poles.

 

[cjstroh]

You probably just unplugged the seat to test it. What I suspect is the seat switch connector has a failed shorting strip. If this is the case then the switch is being out as if no one is in the seat.

Good thinking, but the seat sensor is tested and working properly, I have tested it manually before reinstalling and after installing as well.

 

[StarTech]