210H engaging electric pto kills engine

[TC10284 111]

I have a 210H with an electric pto. As soon as I engage the electric pto switch, it kills the engine immediately. I can spin the blades by hand with ease. I've also tried temporarily bypassing the seat safety switch but no luck with that either. 

 

Anyone have any ideas? 

I'm only used to the manual pto. 

Edited July 20 by TC10284

[gwest_ca-(File Mod) 11,078]

One half of the pto switch in OFF supplies a ground for the starter solenoid.

It also supplies the ground for the pto clutch when ON.

 

The other half of the pto switch controls the ignition. When the pto is ON the seat switch controls the ignition. It grounds the magneto to kill the spark.

Make sure the seat switch opens with operator in seat.

 

In testing make sure you don't allow any voltage to the ignition wire. That would smoke the magneto. The ignition wire is simply grounded to kill the spark.

 

Download this file that has simple explanations for each circuit.

 

[squonk 41,209]

Bypassing the seat switch. (by connecting the wires together) makes the system think you are off of the seat. Leave the seat switch wires disconnected and try it. If the issue goes away, you've found the problem

[TC10284 111]

10 hours ago, squonk said:

Bypassing the seat switch. (by connecting the wires together) makes the system think you are off of the seat. Leave the seat switch wires disconnected and try it. If the issue goes away, you've found the problem

 

Just to make sure, on any of my other WH (300, 400, 500 series), if I jump the seat switch with a short wire, that allows me to engage the manual PTO. Is it the opposite on this model? 

[TC10284 111]

10 hours ago, squonk said:

Bypassing the seat switch. (by connecting the wires together) makes the system think you are off of the seat. Leave the seat switch wires disconnected and try it. If the issue goes away, you've found the problem

 

I'm gonna try that when I can, because from what I can read off the manual gwest posted, what you are saying looks correct. 

 

[John c 79]

I had a neighbor once with a big box cub cadet with a dying battery, he would jump start it and it ran fine, then die when he engaged the clutch, so what kinda shape is your battery in? Is it strong enough to crank/start the engine? Is the charging system on the engine working properly? 

[TC10284 111]

So I just tried this again without the jumper on the seat switch wires but same behavior. Engine dies immediately when engaging PTO. 

 

I am using a fully charged battery booster to start it. 

 

Could it be a bad ignition switch? 

[John c 79]

I am using a fully charged battery booster to start it.

 

????

[953 nut 55,461]

On 7/21/2024 at 2:20 PM, John c said:

I had a neighbor once with a big box cub cadet with a dying battery, he would jump start it and it ran fine, then die when he engaged the clutch, so what kinda shape is your battery in? Is it strong enough to crank/start the engine? Is the charging system on the engine working properly? 

With a Magneto ignition system the engine provide its own power for spark. A dead battery may prevent the PTO from working but would not stop the engine.

[Handy Don 12,310]

55 minutes ago, 953 nut said:

With a Magneto ignition system the engine provide its own power for spark. A dead battery may prevent the PTO from working but would not stop the engine.

The way to electrically stop a magneto engine is to ground the magneto. The PTO switch, in concert with the seat switch, does that.

 

The seat switch CLOSES (i.e. completes the circuit) when the operator is off the seat.

The orange-dark blue PTO switch CLOSES when the PTO is engaged. 

When both are closed, engine shuts off.

 

A short to ground in the orange wiring from the PTO switch to the seat switch, or a broken seat switch, is what I’d be looking for. 

Edited July 31 by Handy Don

[953 nut 55,461]

On 7/20/2024 at 6:00 PM, TC10284 said:

 

Just to make sure, on any of my other WH (300, 400, 500 series), if I jump the seat switch with a short wire, that allows me to engage the manual PTO. Is it the opposite on this model? 

Not all Wheel Horses are wired alike. IF your 300, 400, 500 series has a kill relay then this statement could be true depending on other factors.

 

Check the orange wire from the PTO switch to the seat switch, it could have become grounded out to your sheet metal.

 

Frequently we field questions about safety switches and many times the answers given may or may not be correct for the particular Wheel Horse we are talking about. For accurate information it is best to refer to the “Demystification Guide” or electrical drawings for the specific model and year tractor. There is no one size fits all answer, I will attempt to provide a little food for thought and some general information on the subject.

First, we need to understand how various switches receive their names. The switches used in safety systems are momentary switches, if no force is applied to them, they return to their “Normal” position. That would be the same condition (open or closed) that they had when they were on the shelf ready to be installed. Some will be NO (normally open) and some will be NC (normally closed). In the case of PTO switches there are two switches ganged together.

The seat switch and half of the PTO switch are used in the ignition circuit. The second half of the PTO switch is in the starter circuit.

As an example, the Seat and PTO safety switches for a Magneto or Trigger Ignition system are designed to ground out the magneto if the PTO is engaged and there is no driver in the seat. These switches are in series. The seat switch is a N.C. (normally closed) switch which opens when weight is placed on the seat. The half of the PTO switch that is in the ignition circuit is N.O. (normally open) which is open when disengaged and will close when engaged. With the PTO switch closed and no weight in the seat the magneto will be grounded and the engine will stop running. With the PTO disengaged the seat switch will have no effect.

If the tractor has a Battery Ignition system the PTO and Seat safety switches are wired to interrupt the power from the ignition switch to the ignition coil when the PTO is engaged and there is no driver in the seat. These switches are in parallel. The seat switch is a N.O. (normally open) switch and will close when weight is on the seat. The half of the PTO switch that is used for ignition is N.C. (normally closed) and opens when the PTO is engaged. Both of these switches receive power from the ignition switch “I” terminal and either one being closed will pass the power on to the ignition coil. If the PTO is engaged that switch will open, as long as there is weight in the seat the engine will continue to run because the Seat switch will be closed. If the weight is removed from the seat while the PTO is engaged the engine will stop. If the PTO is disengaged the seat switch has no effect.

Looking at the drawings below should clarify this muddy issue.

 

[John c 79]

With a Magneto ignition system the engine provide its own power for spark. A dead battery may prevent the PTO from working but would not stop the engine.

 

Oh I used to think the same thing until saw the cub cadet across the street do it

[squonk 41,209]

If a magneto tractor has a kill relay or other such device, I could see where you would need a battery to keep the device from grounding the magneto. Depending on how it works. Perhaps the kill device needs power to unground the mag. It would need to be a pretty dead battery to kill it though. The electric PTO can draw close to 20 amps. So a weak battery could cause an engine shutdown with the PTO engaged

Edited August 1 by squonk

[TC10284 111]

So I put a fully charged battery in the tractor earlier and tried the pto again, but same behavior. It immediately kills the engine. Although the pto does engage for a brief second before the engine is killed. Meaning the blades spin down a few rotations. 

Edited August 30 by TC10284

[TC10284 111]

I messed with it more today. I was able to actually get the deck engaged after messing with the carb some more. I'm pretty certain it is nothing more than the initial load put on the engine is what is/was killing it. I got it pretty decent and mowed the yard some, but the engine still sputters and surges. I've cleaned the carb a few times and still no luck. I don't think this is the correct carb, as it looks like a cheap aftermarket. I have to run the idle screw on top allll the way out until it is loose and shakes in its seat for it to idle even somewhat decent. And at full throttle, i can't ever get it to smooth out the surges no matter what adjustment I use on the bowl screw. 

 

I also swapped the ignition switch with a new one but I don't think that was the issue. 

 

I've been trying to find the correct Briggs part number for even an after market carb and doesn't seem like I can find one that isn't crazy expensive. 

 

Best I can tell, the correct carb part number is 491562 for my engine. 256707 0119 01 is the model and type of the engine. 

Edited September 2 by TC10284