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Hi all,

I was mowing today, and the engine stalled for no apparent reason. It started again just fine, but if I engage the blades, the motor shuts off instantly (no sputter, just stalls). Even if I just move the lever to engage the blades a tiny bit, the engine immediately dies.

I have read several posts on the internet which have stated that this is a problem with the safety switch on the seat. I suppose I should just order this and replace it, but first I wanted to ask:

This might be unrelated, but I have attached photos of a little box that has wires plugged into it. It has a piece of metal sticking out of the end that looks like it should be screwed into something. It just hangs loose in the engine. Could this cause an issue with the engine? If so, what trouble would it cause? I assume it is no problem, but I wanted to double check.

And back to the seat switch: a few posts mentioned about unplugging a wire in the engine that would prevent the switch from shutting off the engine (in order to confirm that the switch is indeed the problem). I couldn't seem to figure this out. There are several wires that come out from under the gas tank. I assume most of these wires are coming form the switch.

The engine is Briggs & Stratton 28N707, the mower is a John Deere Sabre 15.5/42 HYDR

Thanks for any pointers. I appreciate your time and efforts. I am not too familiar with repair, but I am willing to try to figure these things out.

The little box is a relay and the metal tab is the mounting bracket.
It should be bolted to the mower somewhere to keep it out of the way but the mounting bolt has fallen off.
It will not affect the mower in any way but should be tied up somewhere out of the way to prevent the wires chaffing through and causing a short circuit.

Your problem could be electric or fuel.
Start the mower then apply the brake. get off and manually increase the engine speed by moving the throttle to full open .
It is the butterfly at the back which should have a thin rod attached to it going to a long flat rod.
If the engine dies when the throttle is opened fully and please do not hold it open for more than 20 seconds or so to prevent over reving damage to your engine you have a fuel problem.
If it accelerates happily and will stay wide open for 20 seconds or so then the problem is with your electrics.
Check the seat switch by starting the engine then raising off the seat.
With the parking brake on the engine should stay running.
With the parking brake off the engine should cut out.
Do it both ways several times and try getting off then releasing the brake.
If it works properly every tie then the seat switch is OK.
The wiring between the seat switch and the PTO switch might be faulty but the switch is OK .

Hello, and thank you for your informative reply.

I just started my mower, put the emergency brake on, and the mower continues to run if I get off of the seat.

Also, with the emergency brake off, the mower shuts down if I get off of the seat, so the seat switch seems to be working in that regard.

While I had the engine mower running, I turned the throttle down to the lowest setting, and then back to the highest setting, and it seemed to react normally and run fine at all throttle settings.

My suspicion is that if there was a gas problem to the effect that there is not enough power to turn the blades, then the mower would not shut off so immediately when the lever to engage the blades is just barely moved. The mower shuts off in the same exact way when I touch the blade engage lever as if I were to rise off of the seat to cut the engine off. It doesn't seem that there is more of a load being put on the engine when the leaver is moved less than an inch, but the motor shuts off whenever it is moved just the slightest bit (and I mean not anywhere close enough to actually engage the blades).

You mentioned something about wiring between the seat switch and the PTO switch. Could this be something that got disconnected or corroded?

Also, I am not sure if I understood right about testing the full throttle. Did you want me to use the throttle lever to turn the throttle to full, or did you want met to actually hold open the butterfly flat metal piece on the engine further open than the throttle adjustment moves it?

Thanks again. If anyone has any tips to further diagnose the possibility of the switch causing this issue, please let me know. Otherwise, when I get a chance, I will try to continue researching other people with similar problems to see if I get get any other ideas before ordering a new seat switch.

Good good, we are getting somewhere.

Yes I want to to open up the throttle butterfly , slowly all the way.
When you engage the blades the engine slows and the butterfly opens up to compensated for the slow running engine.
If there is a fuel supply restriction or air leak when the throttle is fully open the engine starves out but from what you have said so far it really sounds electric
And the problem will be between the seat switch and PTO switch.
I will have a dig around to see if I have a wiring diagram for your mower.
JD like to use relays and it could be the relay you had in your hands that is the problem after all.

Hello,

I will attempt to find a wiring diagram at some point this week when I have time. If I find it, I will link it to this thread. Thank you so much for your advice.

Also, I will get back to you once I can test the throttle butterfly as you have suggested. Thanks again.

The best I have been able to come up with are some parts diagrams. I don't know if these will help at all...

The reason your mower shuts off when you start to engage the mower is that a wire under the mower some where has had the insulation rubbed off and either the lever or the linkage contacts the bare wire and grounds out the engine. You will have to look under the mower and move the lever and see what is rubbing any wires under the mower. Any wire that is contacted by the lever or linkage should be inspected. When you find the bare wire tape it and move it away from the lever or linkage. I view those "SAFETY SWITCHES" as a PITA and bypass them, my $.02.
Good luck

Dana

Thank you Dana for your input. I will try to follow some of the wires underneath to see if I can come up with anything.

If I had a better understanding of the wiring, I would bypass the safety switch altogether, but I do not want to cause more issues with the wiring than I already have.

I'd advise all of you to keep what you do in respect to Federal EPA required controls to your selves and hope you are never involved in a personal injury accident with your mower.

Walt Conner

Tinkerer200 said:

I'd advise all of you to keep what you do in respect to Federal EPA required controls to your selves and hope you are never involved in a personal injury accident with your mower.

Walt Conner

Click to expand...

Hi Walt

I have Toro riding mower and I was curious if you would know why they would make it so it slows to a crawl when you turn the steering wheel. It only goes 3 or 4 MPH when going straight and when turning the sharper you turn the slower it goes. It only goes about 1/2 MPH in a sharp turn. 3 or 4 MPH isn't fast enough to upset even in a sharp turn. When mowing I turn a lot and it was so annoying I got rid of that feature too.

Dana

dana a said:

Hi Walt

I have Toro riding mower and I was curious if you would know why they would make it so it slows to a crawl when you turn the steering wheel. It only goes 3 or 4 MPH when going straight and when turning the sharper you turn the slower it goes. It only goes about 1/2 MPH in a sharp turn. 3 or 4 MPH isn't fast enough to upset even in a sharp turn. When mowing I turn a lot and it was so annoying I got rid of that feature too.

Dana

Click to expand...

I have no idea but sounds very annoying.

Walt Conner

dana a said:

Hi Walt
I have Toro riding mower and I was curious if you would know why they would make it so it slows to a crawl when you turn the steering wheel. It only goes 3 or 4 MPH when going straight and when turning the sharper you turn the slower it goes. It only goes about 1/2 MPH in a sharp turn. 3 or 4 MPH isn't fast enough to upset even in a sharp turn. When mowing I turn a lot and it was so annoying I got rid of that feature too.
Dana

Click to expand...

Easy one to answer.
When used in a dangerious mannar contry to the instructions in the operators manuals some mowers can tip over when turning too sharply at too high a speed.
Mr Idiot Moron gets new mower charges strait into the yard, tips the mower over and severs his spinal column so he can no longer work, pay the mortage feed the family.
Mr Smarty Pants lawer mounts a case against Toro and bumps it around court rooms till he gets a creationist judge who awards a massive damages claim against Toro who are then forced to modify their mowers so no brain dead idiot moron can possibily hurt himself.
We got thousands of Rider Pro's down here after the courts banned them in the USA because if you turn too tight on a slope larger than he maximim allowable mowing slope the mower flips over.
A little latter Husqvarna modified the design and you got the USA only Pro Riders.

Blade cut offs became manditory because of all the idiot morons who shove their hands in the discharge chute to clear a blockage but if you go to your local casulty you will find they still get loads of hand injuries due to operators clearing out the discharge chute with their hand. Then ask them how many brain dead come in missing a finger because they tried to "flip" a belt back onto a moving pulley. All of these clots dissabled the seat switch following the instructions of all the You Tube experts then found out why it is there.
Mowers are very price sensitive so no mower makers goes around looking for expensive safety features to fit to their products.
As for me I would be happy for all safety features to be removed from all mowers then hopefully a lot more idiots would kill themselves hopefully before they had time to breed more idiot morons.

Down here when you take delivery of a new mower, the delivery man takes the key with him.
Your keys are inside a sealed envelope with the message "Read Operators Manual before using mower- serious injuries can result from improper use "
The envelope is stapled inside the instruction book with all of the other paper work inside a sealed plastic bag with a similar warning printed on it.

I think I've found the problem, which is a broken wire under the seat. I cannot find the corresponding end of the wire. The wires go between metal portions of the mower body and seem inaccessible. I will look into this further when I have a chance.

pajohn said:

I think I've found the problem, which is a broken wire under the seat. I cannot find the corresponding end of the wire. The wires go between metal portions of the mower body and seem inaccessible. I will look into this further when I have a chance.

View attachment 29941

View attachment 29942

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Black on white and white on black are the colours used by JD for the ignition cut out.
One is before a switch and the other is after the switch.
If that bare wire is grounding it might cut out the engine.
For the time being just tape it over .
Good chance it was for the RIO ( rear mowing cut out ) switch and disconnected but not tied up out of the way.
The most important safety switch is the seat kill which is working on your mower.
Tape it over then try to mow.
If you can mow while going backwards it is the RIO switch connection and you can forget about it provided you don't mow with live power wires on the lawn or todlers behind you.
If you can turn on the blades , apply the parking brake then get off the seat without the engine stopping it is a wire from the PTO safety switch to the engine.
All of the engine cut out safetys work in parallel so if any wire grounds out anywhere the engine stops.

Thank you so much for providing this valuable information.

I regularly mow backwards when I get in the rough and overgrown stuff, as it takes 2 to 3 passes to cut it all down (realistically I should be using a brushhog, but that isn't going to happen any time soon). I had no idea that it was supposed to cut off when I did so, but I am the only person on the land when I am mowing, and the worst I could run over is a garden hose or dead branch, both of which I have done, but usually not in reverse.

I will report back after I put some electrical tape on the exposed wire. It sounds like the exposed wires just became pressed against the mower body and caused the engine to ground out when engaging blades.

I taped up the exposed end of the wire and made sure it wasn't touching any metal. I started the mower and tried to engage the blades with no success (same results as before). I was still able to apply the parking brake and get off of the seat while the motor runs, and without the parking brake, the motor shuts off if I get off of the seat.

One thing I noticed is that the drive belt seems to be making extra noise on the back pulley. It is hard to see in there, but I didn't notice anything jammed in the belt or anything. I will try to further inspect it and the wiring when I have time.

Some where on the inside of the PTO lever will be the PTO cut out switch.
It will be connected to the seat switch so you can follow the seat switch wires to find it.
The cut outs are wired
Seat + Brake
and
Seat + PTO

We know the seat + brake s good so that leaves the seat + PTO.
We know the seat switch is working so that leaves you with the PTO switch or the wire between the PTO switch & the seat Switch.

Usually the seat switch will have 1 if not both terminals double wired and it will be one of those wires.
IF it is a 4 terminal seat switch, check that both pairs are open circuit when the switch plunger is depressed as would be when you are on it.

Tinkerer200 said:

I'd advise all of you to keep what you do in respect to Federal EPA required controls to your selves and hope you are never involved in a personal injury accident with your mower.

Walt Conner

Click to expand...

"Federal EPA"? When I see Federal anything I head the other way, especially the EPA! I don't trust them, I don't like them! I understand what you're trying to convey Walt but we're on different wavelengths here. Glad to know another JD fan anyway!

Eric Haulenbeek

I have a Toro lx500 circa 2006. The engine starts and runs fine until I engage the mower blades. The motor shuts down immediately. THERE IS A BLINKING SYMBOL on the display panel that is not in the manual. I suspect it is signaling the problem. WHAT IS a rectangle with two opposing triangles ? The TORO dealer doesn't know or won't say. I recently replaced the battery, starter solenoid, and starter. Mower ran fine first use afterward....don't want to spend $2k on new mower or TORO repair bill. HELP !