Ryobi 40V Mower Cutout Fix

I’ve had my battery-powered 40V Ryobi mower (model #40108) for a year now and have been pretty happy with it.  However the last time I used it the damn thing would randomly shut off while mowing.  At the time there didn’t seem to be any rhyme or reason to the problem such as heavy grass or a weak battery which was reading 2/4 bars.  I threw the battery into the string trimmer and it worked great.

So I took the lovely slime-green plastic cover off to see if there was anything obviously wrong.  My hopes were low because I figured the mower would consist of a motor and control board.

Simple mower internals

Sure enough nothing looked wrong such as a leaking capacitor on the control board.  But while putting it back together I noticed a kill switch I had never noticed before!  It’s located by the handle hinge, ensuring that the mower will only run while the handle is in the folded-out position.

This little switch was flopping around in its hole because one of the spring clips on the backside was broken probably while I was removing that slime-green plastic cover.  When the handle is folded out the switch is depressed, closing the circuit allowing the mower to run.

If you take a close look at the interaction between the switch and handle, it is  not a precision operation.  Due to the position of where the switch happens to be, the handle bumps into it, hopefully depressing it.  Here’s the root cause of my problem: The mower’s frame had loosened up over time, allowing the frame to rack from side-to-side during turns.  This racking let that little switch spring back up, opening the circuit and stopping the mower.

And thankfully the solution was to tighten these two T25 frame bolts, located right above the rear wheels.

Keep these bolts tight

And as a footnote, I bypassed that dumb switch just to avoid this kind of nonsense in the future.  The connection was wrapped up with electrical tape after these photos were taken.

I hope this short article helps someone out!

10 thoughts on “Ryobi 40V Mower Cutout Fix

  1. This information helped me. The plastic handle clamps need to be securely fastened. I hope these plastic clips hold up over time

  2. Thanks for taking the time to write this! My mower was having the same intermittent issue. Yanked that switch out and hardwired it as well.

  3. After a few uses, my mower did the same thing. My Google searches all provided the same resolution you provided. I removed the cover of my mower and bypassed the switch. I went back to mowing and after a few minutes, the mower would cut off again so obviously the problem wasn’t the side handle switch. I opened the handle assembly where the bale and start lock switch are. I found that there is a small lever on the bale that engages the main power switch. The bale had enough play from side to side that the lever would not always press hard enough against the switch and the motor would shut off. With a lot of movement of the mower this would happen repeatedly. I tied a narrow cable tie around the end of the bale before it exits the handle casing and widens where the switch lever is to keep it from moving side to side. After reassembling the handle case it tested fine. No more spontaneous shut offs.

  4. I’m having the same problem with my Ryobi. No matter how many shims I put between the handle and the red button, it still quits.
    Can you tell me how you disabled that shutoff switch?

  5. Great info. I put a piece of cardboard between the handle and the button and it worked just fine. Next project will be to splice the circuit closed, until cardboard!

    Thanks for the assistance.

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