Riding Mower Repair Uncovers Miniature Culprit

Most people would be pretty upset it the lawn mower they spent $4,000 USD on had a major failure within the first year of owning it. But for [xxbiohazrdxx], it was an excuse to take a peek under the hood and figure out what brought down this state-of-the-art piece of landscaping gear.

It should be said that, at least technically, the Husqvarna TS 348XD in question was still working. It’s just that [xxbiohazrdxx] noticed the locking differential, which is key to maintaining traction on hilly terrain, didn’t seem to be doing anything when the switch was pressed. Since manually moving the engagement lever on the transmission locked up the differential as expected, the culprit was likely in the electronics.

Testing the dead actuator.

As [xxbiohazrdxx] explains, the switch on the dash is connected to a linear actuator that moves the lever on the transmission. The wiring and switch tested fine with a multimeter, but when the actuator was hooked up to a bench power supply, it didn’t move. Even more telling, it wasn’t drawing any power. Definitely not a good sign. Installing a new actuator would have solved the problem, but it was an expensive part that would take time to arrive.

Repairing the dead actuator seemed worth a shot at least, so [xxbiohazrdxx] cracked it open. The PCB looked good, and there were no obviously toasted components. But when one of the internal microswitches used to limit the travel of the actuator was found to be jammed in, everything started to make sense. With the switch locked in the closed position, the actuator believed it was already fully extended and wouldn’t move. After opening the switch itself and bending the contacts back into their appropriate position, everything worked as expected.

A tiny piece of bent metal kept this $4,000 machine from operating correctly.

As interesting as this step-by-step repair process was, what struck us the most is [xxbiohazrdxx]’s determination to fix rather than replace. At several points it would have been much easier to just swap out a broken part for a new one, but instead, the suspect part was carefully examined and coaxed back to life with the tools and materials on-hand.

While there’s plenty of folks who wouldn’t mind taking a few days off from lawn work while they wait for their replacement parts to arrive, not everyone can afford the luxury. Expedient repairs are critical when your livelihood depends on your equipment, which is why manufacturers making it harder and more expensive for farmers to fix their tractors has become such a major issue in right to repair battles all over the globe.

57 thoughts on “Riding Mower Repair Uncovers Miniature Culprit

    1. I was checking out a craftsman rider that my son-in-law got free . I think is was a 2007 model but looked like new . Previous owner couldn’t start it so it sat in garage for many years . He bought a new one . First I found it had hydro lock too muck oil in it . Drained oil and turned over motor with spark plug out . Then of course it needed a new battery . I got it running he mowed lawn . But next day battery was dead . To shorten story I put new ignition switch in it . That soled problem
      . But I examined old switch and there was a line of organic material which I assume was spider crap between contacts on switch . Cleaned it and it worked fine . That spider crap was shorting that charging circuit ain’t that a bunch of crap but true

  1. It’s also a testament to how something mechanical can always be fixed, whereas something solid state electronic usually means ordering a new part.

    Suppose for example that the dead microswitch was a dead Hall sensor.

    1. …but is a hall sensor as likely to be dead as a microswitch is? The answer of course is “it depends”, but in general, there’s a reason why fewer moving parts is often lauded as a reason for reliability. Signed -A Wise Guy. :-D

    2. I’ve had at least 4 mowers of that class that were not economically repairable. They get fancier every year but they’re designed for a price and for appearance. They’re basically disposable. But, they have cup holders.

      1. That’s the main reason I refuse to give up my reel mower. Fuel shortage? I’ll still cut my grass. EMP from airburst thermonuclear devices? I’ll still cut my grass. DRM lockout preventing right-to-repair? I’ll still cut my grass. Blades dulling? I’ll wipe on some sharpening paste and… cut my grass. Plus, it’s good exercise!

        1. Here in the mountains, you certainly would be up the creek. Pushing that mower up the hills would be impossible without at least a pony to pull it. (They are too steep to walk across the hill). However you then have vet bills, ferrier costs, and feed/shelter costs! Even my walk behind is four wheel drive, and at times that doesn’t work. After mowing two acres, it’s a better workout than going to the gym. At 70, I definitely get a workout every week.

    3. As is so often the case. Fixing works out far cheaper than replacing. It wouldn’t be the first time an inexpensive part has been the culprit. Be it a microswitch in a lawnmower or an internal fuse in a flat screen tv. For those willing to investigate, it can be a great money saver, or at the very least, a good educational experience.

  2. “within first year of owning it” … wasn’t the infernal machina under “warranty” ? (which is probably certainly void by now since he dared to DIY the fix).

    1. Midway through the Imgur album, [xxbiohazrdxx] comments that while it was warrantied he would need to rent a trailer, haul it to the dealer, and be without a mower while they repaired it.

  3. Respect!! This is the epitome of what it means to be a hacker! Looking at the whole item and finding out how each and every part works. Also, being able to determine what needs to be fixed and how to fix it. I find it much more fulfilling to spend the time to find out exactly what is wrong with something and see if I can fix it. 95% of the time, it is doable and the money that is saved is worth the effort.

  4. I’ve repaired small engines and mowers for a living in the past and the #1 problem people have with their riding mowers is crappy safety switches and poor electrical switches in general. They’re really pathetic and are treated like an after-thought. The units themselves cut grass well, but the lack of quality switches renders them often no better than a pile of junk metal.

      1. That’s why I only burn non ethanol in my lawn tractor, I got tired of rebuilding them, I also found on the B&S 23hp intek the abs manifolds that bolt up to it warp so I fit it to get rid of air gaps..

    1. When I look back on life and wonder why I didn’t become an engineer I think about what happens to the engineers that earned that degree making “C’s” ……. And then I discovered the riding lawn mower is this. C student Engineers become Lawn equipment engineers.

  5. If you need a locking diff to cut your grass, you either need a strimmer, or to rethink your gardening design.

    Good work finding and replacing the micro switch though.

    1. I once drove through a village where owners had to tie there lawn mowers to stakes and cut the lawn is circular sections because of the lawn angle. A rideon with a locking diff seams perfectly reasonable.

  6. I went through this with the door lock switch on my washing machine. I tore it open and had to redo a solder joint that had caused the magnet wire to break. It was dark thirty and the replacement part was over a week away. Sometimes it is way easier to fix it, and if you have the skills why not fix it yourself.

    1. Had a washer that was boot cycling. Smelled like dead caps in the psu. Looked like dead caps. Was dead caps. $1.50 worth of bits and she was off again. Close enough to the original values. Bit of hot snot. Hasn’t quit since :-)

      1. Oh right, the point. Miele wanted $250 for a new board. 2 weeks before anyone could fix it. Moral: always have a nosey – especially if whatevers crapped out is out of warranty. Worst case scenario, you learn something :-)

  7. That’s why when i bought my kubota tractor i stayed at 25hp to avoid def. All mechanical common rail diesel, no programming needed if an issue ever arises. Same reason i still have my 16 sierra, i can tune. After 18 gm locked the ecu down like Chrysler. Right to repair needs more attention.

  8. I think the description of how the actuator and switch works was a bit off. You can see the wiring on the back of the motor. The black wire goes directly to one motor lead, while the red wire goes through the diodes and switching circuity.

    The switches are normally closed. Each one is in parallel across a diode. When powered, the actuator will move until it hits a switch, causing it to open. The diode in parallel with the switch is reverse-biased for current in that direction, so therefore the motor stops.

    When you want to make the actuator move the other way, you flip the current polarity. The diode with the open switch is now forward biased. Since the other switch is closed, the motor can spin and the actuator can move until it hits that switch. Again, it will stop because the corresponding diode is reverse biased.

    In the micro-switch, you can see there are two springs balanced against each other. There’s the black coil spring and the piece of thin springy metal that it’s attached to. Normally, the black spring pulls the springy metal into contact with the right-side contact. When you push on the button (not shown), it pushes on the black spring, and the lateral displacement will cause it to pop the end of the springy metal downward and away from the contact. Releasing the button should let it pull the metal piece back toward the contact. However, if the right end can move too far, it can reach a bistable position and not return back up. Or if the left end of the spring got displaced somehow, that can also cause it to get stuck.

  9. I had a similar problem with a push-mover, where a switch on the throttle killed the ignition on 0% setting – USUALLY. that was stuck too… i replaced it with an usual spst switch mounted accessible from outside – with the benefit that i could keep it idling while emtying the grass container. i kept that “zombie” alive for 25+ years. the only original part i had to change was the ignition once (pretty expensive for what it is…)

  10. I have an 80’s riding mower in good condition. It is extremely primitive and mechanical. The good thing about that is that it is very easy to fix whatever breaks. I can often continue mowing an hour later. With some of the newer models the machine would have to be hauled back to the dealers workshop. And there it would sit for at least two months (which is the entire length of the summer where i live).

    It is replaced now by a robotic mower. I love it. But when that breaks I’ll still have my old riding mower as backup :)

  11. ring ring ring
    Yello?
    The Warranty on your lawn mower has expired… press 1 to talk to a consultant, or 2 to have your number removed
    pressed 1
    so how many miles are on your mower?
    dunno it don’t have an odometer…..
    we have 3 payment plans to cover the engine and transmission…..
    I have a very boring life, and run those idiots around in circles

  12. You think this is bad…? Farmers can’t fix their own tractors because of manufacturers designs that make self repairs next to impossible due to high tech. Give me a Farmall, Massy Harris, or an Allis Chalmers…. those were the days of self repaired tractors.

  13. And what better way to start them learning than by sparking an interest and making it seem awesome? And what better way to reach those who “need to stop playing games on your PC” than to present it on a website frequented by those kind of people?

  14. I bought a new Husqvarna from Lowes 4 years ago shortly after the warranty expired I noticed grease on the inside of the rear wheels, I thought wheel seal bad not so transmission seals leaking ok I’ll put new ones in not so have to replace transmission cost around 1000.00 tried to contact Husqvarna no reply from them contacted Lowes sorry it out of warranty will not buy another Husqvarna nor will I purchase another one from Lowes so my advise is you are looking at a Husqvarna don’t

    1. I’ve got a Craftsman YT4000 version of Husqvarna’s smallish lawn tractor that is about ten years old. They do make it about as cheap as inhumanly possible. The biggest annoyance is the stupid drag link steering doesn’t have a good way to adjust the toe-in of the front wheels. The way to fix it is to cut the rod and install a clamp intended for cars – check YouTube for example (or you can bend the rod with a sledgehammer). The other dumb thing is greasing the mower deck blade spindles is useless because the grease shoots into a large void in the casting. I’ve got one spindle getting noisy. There is a fix for the spindle lubrication issue out on the interwebs too. Oh while I am at it – it is kind of annoying that there is a height adjuster on only one side of the mower deck. At least the B&S motor and hydrostatic tranny have behaved well so far.

      All those safety interlocks are a nuisance, but Husqvarna can’t be faulted for being mandated to implement them.

  15. 12 years ago I bought a husky yth2348 lawn tractor after 600 hours it burned 1/2 a qt of oil every mowing. Going backwards sloshed oil to the front of engine and past the rings. I replaced the rings after honing the cylinders took me 2 days but I refuse to buy a new mower over this. This is all because I burned ethanol fuel (I now only burn non ethanol fuel) the ethanol burns hotter due to the water in it.. I am real tired of fixing small engines with carb problems due to this garbage the government makes us buy..

  16. I don’t know what you guys are doing wrong but I got a 1965 John Deere 110 I still mow an acre to this day you just got to know how to work on it older stuff is a lot simpler it lasts longer

  17. One of the contact points is upside-down if you look very closely you can see it. In the third picture that is on that shows the jammed unit look to the right side. You will see the metal connection point that goes to the top and from the left side you can see the other connection connected to a spring. The small round contact is faced down and should be faced upwards to meet up with the upper small contact point. See if you can let the person that shared their fix know if you can.

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