12-38 dies when engaging blades

[Carver 9]

This mower is new to me and the young man I bought it from said his father had the deck off for many years using it to pull the grandkids around in wagons.   He acquired from dad it and re-installed the deck along with new belts and blades.   (Blades were pretty bright green and installed upside down).

 

He told me it runs ( turns out it runs great ! ) but when you start to engage the PTO the engine dies.  I have a TORO Bronco that will not allow you to engage the blades if in reverse. When the engine dies, it sounds like it is losing spark at the moment you move the lever up at all. I am suspecting this mower has the same shut-off switch and it is faulty.  The gearshift says neutral but the mower dies just as quick even if I put the gearshift in forward.

 

If this is in fact the case, can anyone give me a hint of where the reverse lockout switch might be located? 

 

I would also appreciate any alternative possible causes that might cause the motor to shut down so quickly when the PTO is engaged.

Thanks in advance, Phill

 

 

 

 

[gwest_ca-(File Mod) 11,241]

Welcome to Red Square.

Could possibly be a seat switch. Operator falls out of seat and everything shuts down.

Post the model and serial number of the tractor so we can locate the correct wiring diagrams.

[Blasterdad 3,033]

Not sure of the year of your  but this should get you started, on mine the MIR switch is located in front of the seat just below it. 

 

 

[953 nut 57,833]

 

I also would suspect the sear switch or the wiring to it being the cause of your shut down. The attached Owner Manual has a wiring diagram on page 20. The Demystification Guide breaks the wiring down by function. on page 8 it shows the "Spark Circuit Ignition Switch In RUN" which is where you are experiencing the problem. When you activate the PTO and the seat switch is not made up the ignition will shut off.

Check the seat switch and wiring going to it. The switch may be in the seat padding itself.

 

 

[Ed Kennell 40,453]

Most likely the seat switch or wiring to it.    It could also be a faulty ignition switch or wiring to it.

[Carver 9]

Thanks so VERY much to everyone. 

On my Toro Bronco the engine will not start if the seat switch circuit is not open.  I actually had to put a small piece of a snap tie in it temporarily to hold it open when I am working on it and need to start the mower. since this one started OK I assumed that the missing switch was normally open. There is no padding on the seat and the connector under the seat is not connected to anything.  I will try closing the circuit between these two wires and see what that does.

 

 I'll post up when I get this tested this morning but in the mean time, here are the specs on the mower.

Model    # 71184   

Serial    # 5913019   does the serial give a hint of the year of manufacture?

[Carver 9]

Nothing ever goes as simple as it appears..

I installed a new connector on the two leads that would have gone to the seat switch. I never got to test the effect as the mower simply is dead now.  I messed a bit with the switch that contacts the PTO lever yesterday and probably messed it up somehow.  I can see it but cannot get to it at all.  My intention is to replace any and all switches that are suspect but have some personal physical limitations and cannot really waste any physical effort. 
 I am stumped now on how to remove the gas tank. It is quite secure as though it is bolted down. If I get it out I think I can access all the switches and most of the parts that desperately need cleaning. I have introduced the end of a power washer into the cavity and there is still at least an inch of hardened " crud" in places. I won't power wash or even degrease until I am sure of what I am hitting with the stream.

[gwest_ca-(File Mod) 11,241]

The tractor is a 1995 model - the first 2 digits of the serial reversed.

This wiring diagram can be a head scratcher. Not what I expected to see.

 

 

 

 

 

[Ed Kennell 40,453]

55 minutes ago, gwest_ca said:

 

This wiring diagram can be a head scratcher.

I bet the electrical engineer that designed this was really surprised it even worked.

[gwest_ca-(File Mod) 11,241]

Toro shows 4 switches and they are all on this diagram

https://www.partstree.com/models/71184-12-38-xl-toro-lawn-tractor-sn-059010001-059999999-1995/electrical-assembly-3/

 

The detailed diagrams show a "Brake switch" but no brake switch on the above wiring diagram. Perhaps it should be a "Neutral switch"?

[gwest_ca-(File Mod) 11,241]

The seat switch can not be working to power the ignition switch X terminal which passes the voltage to the Y terminal with the ignition in the RUN position. Why? - because the other power source through the pto switch must be working or it would not start. The relay is OK because the tractor runs.

It is possible the ignition switch has failed to make the XY connection in the RUN position.

In any case that yellow wire needs voltage to open the relay contacts so the magneto is not grounded.

 

Switch function is described in the XL service manual starting on page 5-4. There is a link to it farther up.

 

I made some minor changes to the colored wiring diagram above.

[953 nut 57,833]

On 3/18/2025 at 12:10 PM, Carver said:

I never got to test the effect as the mower simply is dead now.

[Carver 9]

With all the gracious help of this group, my $50 bargain is running and the blades will spin up now.    
 My Old 42"Bronco is running again and will remain my main mower, but I am going to keep going on this one. 
I printed the manual and the electrical schematic and they have proven invaluable.

As you can see from the pics, I have more than a little cosmetic work to do as well as a battery and tires ( the ties hold air fine, but are ancient and thoroughly dry-rotted ). 

Now that I know the basics are workable, I will surely find a lot of parts that I will need to replace as the budget and time allows.

As I am an extreme newbie in this repair/restoration effort I am just shooting in the dark trying to locate various parts for this. Any advice on potential suppliers would certainly be appreciated.

I am located near Dallas, Texas for reference, but not at all adverse to online purchases.

I moved the deck questions to the restoration forum.

 

Thanks again for all the help ,  Phill
 

Edited March 20 by Carver
moved deck question to teh restoration forum

[Blasterdad 3,033]

1 hour ago, Carver said:

With all the gracious help of this group, my $50 bargain is running and the blades will spin up now.    

 

I'm glad you got it fixed, what turned out to be the problem?

[Ed Kennell 40,453]

2 hours ago, Blasterdad said:

what turned out to be the problem?

                            We need to know.

[Carver 9]

13 hours ago, Blasterdad said:

 

I'm glad you got it fixed, what turned out to be the problem?

Seat switch was the initial problem, but I created another when I was trying to see if the PTO switch was bad. I had no idea of how things were laid out and pushed and pulled on the slim lever that the PTO shaft triggers. I had bent it badly so that it would not trigger the switch.  Once I got the gas tank out of the way I could clearly see the switch and test it. I just bent the lever back and while it works fine right now, I will need to replace the switch or jury rig a stiffener on the thin flexible arm that I bent. The actual switch is crisp and works fine.
This was the first time I used one of the " lever lock" wire nuts and I am in love with them. One now lives permanently where the seat switch wires connected to the now missing switch.

 

This has turned out to be a blessing since I now know how to get my Bronco to reverse and keep the blade spinning. The lake house is just under 2 acres with 24 very large pecan trees and many smaller shrubs. I bought the bronco new 15 years ago and the only thing I disliked was having to disengage the blade to back up a foot or two just to navigate the yard.  It typically gets used 4 or 5 times a year and is still like new other than it is time to replace the original tires. I am on battery #3.

 

 

Edited March 20 by Carver

[953 nut 57,833]

On 3/19/2025 at 7:32 PM, Carver said:

As I am an extreme newbie in this repair/restoration effort I am just shooting in the dark trying to locate various parts for this. Any advice on potential suppliers would certainly be appreciated.

I am located near Dallas, Texas for reference, but not at all adverse to online purchases

Tractor Supply or Rural King would be two good local sources for most stuff. A couple of good Wheel Horse specific parts are A-Z Tractor https://www.a-ztractor.com/ and Wheel Horse Parts and More https://wheelhorsepartsandmore.com/shop-now/.   In both cases it is best to call them to get their suggestions on parts availability.

[Carver 9]

Thanks 953 nut. 

I have a Tractor Supply not far from me, but have not heard of Wheel horse parts before.

I'll have some time online this evening and do some scouting around.

Getting this thing going has been a bit of fun actually, so I am guessing getting looking good will be also.