Like many others, the 2015 John Deere D125 Lawn Tractor (aka ride-on mower or garden tractor) has two annoying safety switches. One stalls the engine if you mow in reverse without pressing a button. The other stalls the engine as soon as you get off the seat (or lean too much forward or to one side). This post is about disabling/bypassing the (newer) seat safety switches.
Unlike older models, the new seat safety switch now has four pins, and not just two wires, so things are a little bit more complicated than the ‘cut and short’ solution presented on many older YouTube videos. ‘Cut and short’ will not work on the newer safety switches.
I conducted some research and found out that the switch itself is JD Part Number GY20073. It is available for next to nothing to people in the US, but the price increases by a factor of about 500% when you try to get it in Australia. Further research reveals that the (alternately-branded) Rotary 14246 Plunger Safety Switch is identical and much cheaper to source in Oz.
Having thus acquired a seat safety switch, I then used a multimeter to test the electrical continuity between all possible combinations of pins. This was first done with the switch in its default ‘off’ position (spring-loaded pin all the way up) and then in its ‘on’ position (pin pressed down). Here are the results:
- switch ‘off’ (pin up)
- open circuit: 1-2, 1-3, 2-4, 3-4
- closed circuit: 1-4, 2-3
- switch ‘on’ (pin down)
- open circuit: 1-2, 1-3, 1-4, 2-3, 2-4, 3-4
- closed circuit: nothing
What this tells us is that when no-one is sitting on the seat, the outer pair of pins are connected and so are the inner pair of pins, but when a person sits on the seat all of the pins are disconnected. This is surprising, as what it means is that to simulate a person sitting on the seat (the pin being pressed down) all you need to do is make sure none of the wires are connected — and that would be as easy as just unplugging the connector from the safety switch!
This was such a surprise that I actually didn’t believe it. It doesn’t make sense to build a ‘safety’ switch that can just be unplugged by an end user.
Closer examination of the switch with a magnifying glass revealed some imprinting: 63DH, DELTA SYSTEMS INC, STREETSBORO OHIO, US PAT NO 6,207,910. Examining the patent online made for a couple of hours of painstakingly slow but interesting reading.
The patent for this switch describes it as a “low profile, two pole, plunger-type safety switch”. The electrical testing confirms two pole behaviour. What was really interesting, however, is that the patent also includes the design of the connector — and the interaction between the two is where some clever engineering magic happens.
As “it is desirable to prevent an operator from bypassing the operation of the safety functions provided by a seat mounted safety switch by simply disengaging the connector coupled to the switch housing” the engineers designed the connector to short-circuit the two middle wires in the connector itself when it was unplugged. Sneaky devils!
As can best be seen in FIG. 12, when the connector housing 202 is engaged with the switch housing 112, the beveled edges of the triangular nubs 127 a, 127 b extending outwardly from the forward edge of the bottom cover 117 contact and deflect downwardly the arcuate portions 264 of the forwardly extending arms 262 thereby permitting electrically connection or nonconnection between the socket assemblies 210 b, 210 c to be determined by the position of the actuator 130
So, what seems to be happening is that the two middle wires (2 and 3) are being used to make sure that the connector is actually connected to the switch and also sense the position of the pin. If 2-3 is closed circuit then either a) the connector has been unplugged, or b) the connector is plugged in but there is no-one on the seat (pin is up). In either of these cases the motor won’t run. If 2-3 is open then a) the connector must be plugged in and b) there should be someone on the seat (pin is down).
The outer two wires (1 and 4) only sense the position of the pin. If 1-4 is closed-circuit then there is no-one on the seat (pin is up). If 1-4 is open circuit then someone’s on the seat (pin is down).
It is thus almost certain that both 1-4 and 2-3 need to be open-circuit in order for the motor to run.
The utterly trivial conclusion to all of this is that, in order to bypass the seat safety switch in your lawn tractor all you need to do is cut the cable before the connector. Simply cutting the cable and then insulating the exposed ends will ensure that no circuits are ever closed and therefore that all of them remain open — thus mimicking the electrical behaviour of the connector being plugged into the switch and the pin being pressed down.
Wow, just wow.
So, having done my homework and testing, it was now time to put the theory into practice. I had a few hours of mowing to do and a bit of spare time up my sleeve, so I pushed the lawn tractor out of the shed, tilted the seat forward and unceremoniously cut the cable all the way through with some snips. Brought the seat back down, hopped on the seat, applied the brake, pushed the throttle up to the choke position and turned the ignition key — the starter turned a few times and then the engine roared to life. I let the engine warm up for a while and then, with the motor idling, just hopped off the seat… and… nothing changed! The engine kept on running. Success!
I then happily mowed for a few hours, hopping off frequently to open gates, move obstacles and pick up pieces of rubbish — and the engine kept running regardless of whether or not the mower deck was engaged or what revs it was pulling.
Brilliant, just brilliant. Makes mowing so much more efficient and enjoyable! 🙂
Side note: On the JD D125 the seat safety switch cable that you cut is enclosed in a springy plastic sheath that runs down into a hole in the chassis of the tractor. When you tilt the seat forward this stretches and is thus under tension. When you cut through the cable the bottom part will probably withdraw down through the hole and quickly disappear from view. Don’t bother trying to fish through the hole with your fingers, pliers, or a wire. Kneel down next to the right, rear wheel and look just above and forward of the wheel — you will see the cable/sheath clamped to the frame. The part protruding up from the clamp will be the loose end you just cut. Use cable ties to secure this loose end somewhere so it won’t rub against anything metal or collect water. If you are particularly paranoid, or often drive your tractor through puddles, consider even taping or plugging the end with something to seal it.
Remember that the wires in this loose end need to always remain open-circuit. If they are rubbing against metal parts or bridged with a droplet of muddy water, then they can close-circuit and — as far as the electronics of the engine are concerned — signal that the operator has left the seat and result in the engine stalling (or not starting). If the contact is intermittent (as it would be if vibrations were bouncing the wires against a metal part) then they could send conflicting signals multiple times per second to the engine which would result in erratic engine operation (symptoms similar to an engine being starved of fuel). Secure and/or seal the loose end to eliminate this problem from developing down the road.
According to greenpartstore.com the switch is used in (and thus this bypass will work for) all the following models:
- 102, 105, 115, 125, 135, 145
- D100, D105, D110, D120, D125, D130, D140, D150
- E180 (Thanks Jim!)
- L100, L105, L107, L108, L110, L111, L118, L120, L130
- LA100, LA105, LA110, LA115, LA120, LA125, LA130, LA135, LA145, LA155
- LT150 after serial number 040,259
- LT160 after serial numbers MOL160H035097, MO160C035447, MO160D415192
- LT170 after serial number 035,001
- LT180, LT190
- LTR180 after serial number 500,001
- G110
- X110, X125, X130R, X145, X155R
It is likely that many other brands of lawn tractors or garden tractors (e.g. Husqvarna, Sabre, Scotts) use a similar, if not identical switch and can be bypassed in the same way.
Disclaimer
I am neither young nor stupid. I’m never in a rush when I mow. I pay attention to where my feet are. My property is flat and the soil is sandy. The D125 comes to an automatic halt if you take your foot off the pedal. In my particular situation the negatives of a seat safety switch far outweigh the positives. Your circumstances are probably different. Use your brain. Safety switches exist to protect you in a variety of situations where things can go wrong. It is generally not a good idea to bypass them. If you are young and usually rushing to cut the grass on a sloping site with slippery clay soil with a mower that doesn’t automatically stop when you take your foot off, then you’d have to be insane to bypass the seat safety switch. Accept responsibility for your own actions and don’t blame others if you screw up.
Final Thoughts
The reason why such a safety switch design is so effective actually involves psychology. The average person, when faced with an annoying safety switch, may simply try to unplug it. In their mind all the ‘clever stuff’ is being done by the switch itself. They think that by just unplugging the ‘dumb cable’ from the ‘clever switch’ they can stop the ‘clever stuff’ from happening. When this doesn’t work, they are probably a little bit surprised, then plug it back in and are just relieved that the tractor still fires up. Nothing broken — whew!
The average person doesn’t have the technical knowledge or confidence to pursue the matter further. Based on a lifetime of prior experience, connectors are just dumb bits of plastic so there’s no way the connector could have anything to do with the tractor not starting up — they think that an unplugged cable behaves the same as a cut cable (i.e. no electricity goes anywhere). That means ‘the problem’ must be somewhere back in the engine bay itself and, well, that’s all just too hard. The simple strategy failed — give up. People with that mentality are probably the ones that designers are trying to protect from themselves — and rightly so.
Those that do a bit of research, however, find that in order to effectively bypass the switch, they need to actually damage the machine (i.e. cut wires or, alternatively, rip out the shorting member with pliers). A lot of folks won’t be willing to do that because the idea of inflicting permanent, irreversible (in their minds) damage to something they paid money for is a mental obstacle too high for them to overcome. Since this issue is likely to arise when the machine is newly purchased, that makes it even harder. Deliberately damage a brand new tractor — are you crazy?
By moving ‘intelligence’ from somewhere obvious (the switch) to somewhere obscure (the connector), the designers thwart the annoyed masses trying to bypass the seat safety switch. By making the only workaround one that causes damage, the designers further discourage those that are precious about their tractor. About the only folk left are the hackers who just don’t give a damn. If you’ve made it this far you’re probably one of those. I hope you found this post informative. Happy hacking!
- Update (2021-01-10): Disabling Lawn Tractor Safety Switches (Part 2)
tp69 
Actually you can fix the problem of the extra contact points by simply sticking two separate flat toothpicks in between the contact points below where the bottom two connectors plug into the switch. I did this to mine and it works great. Just leave it unplugged. This way you don’t need to cut the plug off and can return it to the functioning safety switch should you decide you need to or want to sell the tractor as originally designed. Thanks for all the “leg work” you did on this switch. You saved me a lot of time.
Rick
Yep, there are a few less-destructive ways to do it. I have no resale plans for the lawn tractor and will never have a need for the safety switch, so a clean cut made the most sense for me. (In fact, when I do the next service I’ll probably trace the cable back to the engine bay and remove it completely.) I’m happy that the details provided saved you some time in developing your own solution — that’s the main reason I posted them. I don’t see the logic in multiple people worldwide having to research the same information. Happy mowing!
You clipped all 4 wires?
Yep. I made sure the ignition was off and then just cut through the whole bundle. It was hard to believe that was all that needed to be done, but I’d conducted my research and testing and was 99.9% sure it would work… and it did.
I very much enjoyed your description of this annoying problem. You sound like you really do know what you are talking about, so I went ahead and cut the wires. I will know in a couple of hours if this solves my problem or not. Its 5 am and just too early to start it up and check it. I am almost positive the wife would be a little more than up set if I disturb her beauty sleep. (God knows she needs more than she gets now).
Anyway… again Thankyou
dave
Heh heh. Experiments can wait — the little lady is always more important. Let us know how things go.
Tim thanks for doing the research and sharing. And Rick, thanks for your response as well. I was simply trying to diagnose the problem so I could see if it indeed was the switch that was causing the issue. I could not find anything on the internet on how to test the switch itself. By using the toothpick approach, I can do just that.
No worries.
I used your remedy on my new D130 today and it worked perfect. Thank you so much for the information.
You’re welcome. Happy mowing!
Great article and it was very detailed. I also found everyone’s comment’s informative. Thanks, you saved me a lot of time. Do you have any other tips on your John Deere maintenance, give us a link or web page.
I’m glad it saved you some time. I’ll be disabling the other safety switch some time in the future, and making a cage for the 17P cart, so will make additional posts when they happen.
I currently have one other post about lawn tractor maintenance: Lawn Tractor Oil Filter Tips.
About the only other thing I can suggest right now, if you have a cart, is to replace your hitch pin with something like a John Deere Magnetic Hitch Pin or Good Vibrations King Pin Lawn Mower Quick Connect Hitch Pin — they let you disconnect the cart from the lawn tractor with a single hand without having to bend over double or get on your knees to pull out or push in a cotter pin. A serious quality of life improvement for older folk or those with back issues.
The Good Vibrations one is a bit long for the D125, so has a tendency to occasionally drag its tip and have it’s mechanism clogged up by long grass or dirt. I ran tape around the top of the shaft (near the handle) to act like a spacer, which increased the clearance between the tip of the pin and the ground, and greatly decreased the rate at which it clogs up. If you’re mowing your lawn on a regular basis, and keep the pin oiled, I think it’d be very, very reliable.
No need to cut any wires. Inside the plastic connector is a metal clip that touches 2-3. Small screwdriver to pop it off. Done. easily reenabled by putting it back in the connector housing.
Yep, I actually mentioned that approach in the Final Thoughts section. I personally prefer permanent solutions, and like ‘simplifying’ the machines I work with. Disabling “Nanny State” circuits is good, but completely removing them is better. I got a chance to do that on the last 50-hour service. 😉 Happy mowing!
Thanks for your hard work. I tried splicing #1 & #2 to # 3/4 per another post, but it didn’t work. Had I read further. I would have tried the toothpick…
Glad I could help. The important thing is that you’ve got a working solution and now own a more user-friendly lawn tractor. Enjoy!
I did the tooth pick fix and it worked, except for when I engage the mower deck it kills the engine.
I have a 2016 model D160 John Deere and I was wondering if it uses a different switch?
The D160 wasn’t on the model list I posted above. A quick search shows that the D160 (also the D170 and models upgraded with a High Back Lumbar Seat) use the AM130453 instead of the GY20073 so (at least at a product number level) they are different. Your experience would suggest that at least something has changed. How they are different electrically, I don’t know — I don’t have a D160 or an AM130453 to test.
You could use the same process I detailed above (i.e. buy a spare switch and then test electrical continuity with the pin up and down) to work out what needs to be cut or shorted to effectively bypass an AM130453. You could also examine your switch for a patent number and check the patent online to see if they’ve done something sneaky with the connector — like they did with the GY20073.
Thanks for the info. As I am electronically challenged, I’m not sure of my outcome.
When you refer to pin up and pin down, are you speaking of the button on the seat switch?
Correct — the pressure pin that is up when no-one is sitting on the seat, and down when someone is sitting on the seat.
Thanks for this DIY hack. This particular model (LA110) only had 3 wires to the seat switch connector (4th wire looped back). I simply cut the 3 wires, kept isolated, re-wrapped them.
The reverse switch bypass only req’d a loopback plug on 2 wire connector on the back of the dash-mounted push switch. Respect for safety first folks!
Thanks for the feedback and I’m glad the approach worked for you!
I haven’t yet been sufficiently annoyed by the Reverse Implement Option (RIO) switch to warrant bypassing it. My main mowing route is one that I can complete by simply doing a handful of clockwise loops. With each loop being ~1400m long and (now) clear of obstructions and dead-ends, there’s no real need for reverse — I just set the D125’s cruise control and then enjoy the ride for ~90 minutes. 🙂
Just bought new 130 mower thinking the previous by pass would work..PTO shuts engine down when turn on.. Sounds like check for new switch. Thanks
2017 D155: The tooth pick trick works for the seat problem. Make the middle two connectors NOT make contact with the mini-flap in there.
Thank you so much, I have a new d125 and will try the tooth pick method as described above before cutting wires, also the reverse switch bypass will be implemented. Enjoyed your style.
You’re welcome.
Yep, for folks that might (for whatever reason) want to re-enable the seat safety switch down the line, wedging the shorting member (imitating the interaction between 127a and 264 in Figures 11 and 12 above) and then zip-tying the loose cable somewhere is probably the best approach.
Cheers, and happy mowing!
Thanks !! To all of you above for sharing your acquired knowledge and experiences. Last night my 1 month old D125 failed to start. I shorted the solenoid but no fire to the plug. Personally I need the switch to work because I am hardheaded and insist on mowing a ditch with mine; the ditch is rather steep and with the center of gravity being so high I want the safety factor. Also, my mower is under warranty and I don’t want to void it prematurely; but the nearest servicing dealer is 45 miles away and I need a way to test the circuits myself. I can replace whatever sensor or part is causing the issue cheaper than I can make two trips to the dealer – plus I need to mow the damn yard … again … Thanks to you guys I now have a plan !!!!
Also, the annoying reverse over ride switch can simply be jumpered so you can mow in reverse. Did that before I ever engaged the blades the first time. It can be plugged back in should I need to take it to the dealer. My thoughts are that I’m a grown man who has been mowing grass without injury for 46 years. If I make a decision to over ride an idiot switch then that’s my prerogative and I bear the responsibility for the consequences – I don’t like strangulation by regulation !!
My property is pretty flat, but some parts of my main mowing loop had ‘rough’ areas on them which introduced a little more tilt for the mower than I was comfortable with. I made notes of the locations, then used spoil from a pond excavation to level them out. Now there’s nothing to worry about at all. If your ditch is relatively small, and you don’t need to retain it, you might consider filling it in?
I disconnected the plug on the switch, then with a pair of channel lock pliers squeezed the two plastic retainers on the switch and removed it from the seat. I zip tied the button in the down position. I positioned it down near the fuel filler and secure it another zip tie. Now I can reinstall it if needed.
Ken, once you’ve zip-tied the pin down, is it possible to just put it back into position? I’m 430km from the tractor right now, but figure that if you can lock the pin down in such a way that it doesn’t mess with clearances, you could just re-attach it.
the slot the switch sits in is a tight fit and there is not room for the zip ties. there is plenty of cable to just hide it in the fuel bay.besides if a problem would happen any distance away from your toolbox you can address it in the field.
I don’t see a metal clip connecting terminals 2 and 3, and I’m not sure how a toothpick would be inserted to separate the contacts. Please clarify.
Figure 15 (which you can see here) shows what the metal clip actually looks like. You can only see the curved ends of it (264) when it is viewed from the front. The location of part 262 on Figure 10 will show you where it is located if you look at the front of the connector.
I didn’t use the toothpick approach, and I’m too far away from the lawn tractor to verify this, but when folks say “use a toothpick” I’m pretty sure they mean “take a toothpick, break it in half, and poke one half into each of the slots”. They don’t mean “use a single, unbroken, toothpick”.
Looking at Figure 10, your goal is to stop part 262 from contacting the metal parts of 210b and 210c (i.e. the bottoms of the terminals marked as 212).
In Figures 11 and 12 look at how parts 127a and 264/262 interact. The toothpick will perform the function of 127a (an electrically non-conducting nub) and push 264/262 down by wedging into the space above it.
When the plug is disconnected, the arms of the clip (262) come into contact with the terminals (212) for both 210b and 210c — thereby closing the circuit between the middle pair of conductors and preventing operation of the engine. When the plug is connected, 127a pushes down on 264 so that 262 does not contact 212 — thereby opening the circuit between the middle pair of conductors and allowing the engine to operate normally (subject to the seat safety pin’s position, of course).
Final note: I think it’s worth mentioning that circuits can be broken (opened) at any point along their length, so technically you don’t need to prevent contact between 262 and 212 at both 210b and 210c, you could just do one or the other. Sticking a single toothpick into only one of the slots will work. Unless you’re using really, really short toothpicks, however, it also means you’ll have a fair bit of toothpick sticking out of the connector. I’m not a fan of ‘bits sticking out’ as they are a source of failure, so snapping off the protruding end makes sense to me. That means breaking the toothpick. If you’re going to do that anyway, may as well just break the toothpick in half in the first place, stick half into each slot, and build some redundancy into your solution. Even if one of the toothpicks manages to fall or work its way out, you’ll still have the other one in there as a backup. Less chance of you happily riding along one day and then having your lawn tractor stall and then refuse to restart for absolutely no apparent reason whatsoever.
I read all of this and was about to remove the jumper wire in the plug because it would do the same thing as cutting it. Just for giggles I tried starting it with it the switch unplugged and it worked. I didn’t have to cut anything or remove the jumper wire. I just left it unplugged. I have a 2017 John Deere D140.
Thanks for the clarification, Tim. I took another look at the connector (with a magnifying glass) and found the metal clip and pulled it out. Problem solved. The diagrams and your explanation do make sense. I just couldn’t see the metal clip the first time. Thanks again.
Since it takes only a couple of minutes to test, unplugging the seat safety switch is the very first thing everyone should try if they find themselves travelling down this path. It’s hard to believe that any decent safety switch can be bypassed by simply unplugging it, but you’ve got nothing to lose and aren’t going to cause any damage, so why not give it a go?
Assuming your 2017 D140 is not some sort of freak, maybe JD have rolled back to a simpler, cheaper safety switch design? Something that still allows them to tick the box saying they have a seat safety switch installed (thus warding off the lawyers), whilst not being encumbered by the additional cost of a tamper-resistant design?
Mine works by just unplugging. Not disproving your article, but just saying. D125, WA, USA
What year was your D125 built?
regarding pulling the plug, my l105 would stay running if i got off the seat, turn on the mower deck, it would shut off regardless if I was sitting on the seat or not… Btw, is the metal clip on the male or female end of the plug?, thanks
See Figure 11 above and look for the piece marked 264. It’s in the piece of plastic connected to the cable that goes to your engine. Given that the pins are on the seat safety switch, that technically means that the plug/connector is female.
Interesting behaviour on your L105. Behaves more like a RIO switch.
Hi …
My boyfriend just purchased a John Deere 130 series lawn tractor . I have just one question will the mower blades keep working ? He wants the blades to still keep engaged also .
Thank you .. Sue
Nanny-state legislation mandates that all lawn tractors/ride-on mowers have safety devices installed to shut down the engine if the ‘operator leaves the seat’ so yes, a new D130 will have that ‘feature’. He will need to find a way to bypass the seat safety switch if he doesn’t want the engine to stop.
Whether or not the mower deck is engaged or not doesn’t really matter — if the operator is not in the seat then legally there is no-one in control of the machine and (so the ‘logic’ goes) it should cease operation completely.
I have a LA120 and my mower behaves the same as Brian’s. Unplugged the switch, engine stays running regardless if on seat or not. When I try to engage PTO to run the mower, it kills. Tried the toothpick trick, and still kills when engaging mower
I wonder if your LA120 and Brian’s L105 actually have a different type of seat safety switch and/or connector? Does the one you have installed match the image at the top of this article?
Great article. Any help with three wire safety seat switch on older craftsman mower?
I’ve never had one of the three-wire seat safety switches, or a Craftsman, so I can’t give you any advice from direct, personal experience.
That said, the current generation (and all previous generations) of seat safety switches all implement simple electrical circuits. Thus they can all be bypassed relatively easily. The process described in this article can be used by anyone to work out a way to bypass a given switch — regardless of the number of pins or wires, or the cleverness of any connectors.
I advise following the same process: 1) Probe the switch with a multimeter to reveal the continuity states. 2) Track down the patent that applies to your switch and see if they’ve been sneaky with the connector. Based on the results you get from doing those two steps, one or more bypass solutions should present themselves.
Thanks so much for doing the hard work for me on this. I just took care of mine with a cut credit card stuck in the connector. I also did the mow in reverse button with a jumper.