# New guy troubleshooting a Toro 5/24



## NRP (Dec 28, 2015)

Good morning! I have somewhat of a dumb question. I am troubleshooting a 1987 Toro 5/24 with a H50 Tecumseh. The machine starts and runs, but will not shut off with the key. I found and corrected some wiring issues, and cleaned a few connections so far. I made it to the engine and found this. I cannot find this piece in any parts diagrams, and I am not sure what it is, or what the wire should connect to if anything. It is located on the lower left of the engine. Can someone identify please? Thanks for whatever help you can give.


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## Shryp (Jan 1, 2011)

Looks like part of a safety system. Does your machine have an little lever that doesn't really do much? It is probably suppose to kill the engine if the auger is engaged and the drive isn't unless you are holding on to something.


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## unknown1 (Dec 13, 2015)

NRP said:


> Good morning! I have somewhat of a dumb question. I am troubleshooting a 1987 Toro 5/24 with a H50 Tecumseh. The machine starts and runs, but will not shut off with the key. I found and corrected some wiring issues, and cleaned a few connections so far. I made it to the engine and found this. I cannot find this piece in any parts diagrams, and I am not sure what it is, or what the wire should connect to if anything. It is located on the lower left of the engine. Can someone identify please? Thanks for whatever help you can give.


If that wire is NOT re-connected, you will probably be unable to shut off the engine. I notice you mentioned that.

In short, the dangling wire should probably be connected to the shared isolated kill terminal about one inch away from its location in your image.
It's almost certainly coming from a kill switch somewhere. Probably that key that you say is not working.

My thread over here describes in lots of details what that wiring is and how it works...

http://www.snowblowerforum.com/foru...heater-box-mtd-5-24-tecumseh-hs50-67324k.html

Especially this image and the descriptions leading up to it

http://www.snowblowerforum.com/foru...eh-hs50-67324k-2015-12-22-17-57-56-arrows-jpg

Different make and model but the concepts are the same


P.S. There are no dumb questions.... only dumb answers!


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## Kiss4aFrog (Nov 3, 2013)

Do you have the model and serial number ?? It would help to be able to look up the wiring schematic if it's available.

https://www.toro.com/en/parts


Not sure if this applies to your machine but you can try following the wires and see.

.


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## NRP (Dec 28, 2015)

Shryp said:


> Looks like part of a safety system. Does your machine have an little lever that doesn't really do much? It is probably suppose to kill the engine if the auger is engaged and the drive isn't unless you are holding on to something.


The only lever is on the right handle bar for the auger safety switch I believe.



Kiss4aFrog said:


> Do you have the model and serial number ?? It would help to be able to look up the wiring schematic if it's available.
> 
> https://www.toro.com/en/parts
> 
> ...


Thanks! It's a model 38040 S/N 7001012



stuart80112 said:


> If that wire is NOT re-connected, you will probably be unable to shut off the engine. I notice you mentioned that.
> 
> In short, the dangling wire should probably be connected to the shared isolated kill terminal about one inch away from its location in your image.
> It's almost certainly coming from a kill switch somewhere. Probably that key that you say is not working.
> ...


Thank you! I knew I came to the right place. I was thinking the same thing about the shared isolated kill terminal you mentioned. I looked for any witness marks that would indicate it had been connected there in the past, but I could not see anything obvious. This machine is one that I rescued when a family member was going to send it to the scrap yard. I have no idea what work was done to it in the past, or by who. I will report back again.


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## unknown1 (Dec 13, 2015)

NRP said:


> The only lever is on the right handle bar for the auger safety switch I believe.


Guessing and reading between the lines.... I have no knowledge of your model... it sounds like you may have two distinct ways of (supposedly) shutting off the engine.

1) The start key (that you say isn't working)
2) A dead-man switch on the handle bars (designed to shut down if you fall or let go)

As described in the thread I pointed you to, they should all work the same way I think... basically they ground out the "kill terminal" on the ignition "coil".

If that's what you think you have... there should be one more wire somewhere that needs to hook onto that "isolated kill terminal" 

....just guessing.


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## unknown1 (Dec 13, 2015)

stuart80112 said:


> Guessing and reading between the lines.... I have no knowledge of your model... it sounds like you may have two distinct ways of (supposedly) shutting off the engine.
> 
> 1) The start key (that you say isn't working)
> 2) A dead-man switch on the handle bars (designed to shut down if you fall or let go)
> ...


just looked up your model....
It's all here..
that's a lot of switches!

http://www.ereplacementparts.com/toro-38040-700000179999991987-snowthrower-parts-c-121776_121777_123476.html

All schematics here: (see Page H)
http://www.ereplacementparts.com/to...snowthrower-parts-c-121776_121777_123476.html


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## classiccat (Mar 1, 2014)

Interlock module is a pretty common fail on toros. It processes the handlebar & auger/traction limit switches to determine if the ignition should be grounded.

I ended up disconnecting mine (noone but me uses the machine) due to intermittent functionality. Our problem is that all of the limit switches are the opposite condition (NC) to simply ground the ignition when either the tractor or auger is engaged & the handlebar switch (NO) is not. The throttle control on the engine itself will still ground the ignition when you throttle down.

So if you have a source of power, we should be able to ground the ignition using a relay. You just won't be able to dummy-proof it against starting the machine with the auger &/or traction engaged.


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## NRP (Dec 28, 2015)

stuart80112 said:


> just looked up your model....
> It's all here..
> that's a lot of switches!
> 
> ...


Thanks again for the help and information. The thread you linked to was a huge help. Unfortunately work has been hectic this week and haven't had time to get out into the garage. In the next day or so I should get out there. I will report back with my findings.



classiccat said:


> Interlock module is a pretty common fail on toros. It processes the handlebar & auger/traction limit switches to determine if the ignition should be grounded.
> 
> I ended up disconnecting mine (noone but me uses the machine) due to intermittent functionality. Our problem is that all of the limit switches are the opposite condition (NC) to simply ground the ignition when either the tractor or auger is engaged & the handlebar switch (NO) is not. The throttle control on the engine itself will still ground the ignition when you throttle down.
> 
> So if you have a source of power, we should be able to ground the ignition using a relay. You just won't be able to dummy-proof it against starting the machine with the auger &/or traction engaged.


I didn't know it was that common to fail, but it makes sense. I am in the same situation you are, in that I am the only one using the machine. The relay idea is very good, and I may have to copy your fix. Thanks for the information, and direction.


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## Rolf Zetterberg (Dec 15, 2012)

We have a small problem here.The interlock module does not work in the usual fashion by grounding(everything to the left of the module is "floating" at an unknown voltage and cannot and should not be grounded.).Instead there's a small current robbed from the ignition coil that is being monitored by the switches and that tells the transistorized module what's going on.If it receives a signal meaning wrong handling by the operator,it shorts the kill wire to ground.
Source:
Toro wheelhorse Demystification Electical wiring diagrams for all WheelHorse tractors


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## unknown1 (Dec 13, 2015)

I took the liberty of redrawing that circuit diagram with fewer crossing wires.
My brain can see it better

I read it this way..

1) If the Key is ON and the handle is PUSHED you are good to run (auger and traction don't matter). Signal transmitted on the top circuit.
2) If the Key is ON and the auger is NOT engaged, and the traction is NOT engaged you are good to run (handle doesn't matter). Signal transmitted on the bottom circuit.

In which case I'm guessing that the place I've been calling the "isolated kill terminal" might be one of the two locations where 3 wires come together in this modified wiring diagram.
There's one to the left of "traction" and one to the right of "auger".
Looking at the initial posting I think I already see 2 wires on that terminal post coming from on high and the dangling wire could be the third.

Obviously would need to trace the wires carefully to be certain. This is a guess. 
Speaking to Rolf's comment about "should not be grounded"... that isolated terminal is indeed not grounded by default...it's made of nylon or plastic.


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## NRP (Dec 28, 2015)

stuart80112 said:


> I took the liberty of redrawing that circuit diagram with fewer crossing wires.
> My brain can see it better
> 
> I read it this way..
> ...


I like your idea of the conventional toggle switch. I would eliminate a lot of items that are no longer available. You are also correct in noticing the two wires going to the isolated terminal that is indeed made if nylon. I have added more detailed pictures. Adding the kill toggle switch would only need the two wires already at that terminal pictured?


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## unknown1 (Dec 13, 2015)

NRP said:


> I like your idea of the conventional toggle switch. I would eliminate a lot of items that are no longer available. You are also correct in noticing the two wires going to the isolated terminal that is indeed made if nylon. I have added more detailed pictures. Adding the kill toggle switch would only need the two wires already at that terminal pictured?


I wasn't actually proposing you add a toggle switch, I was just explaining how I think everything works hoping someone would confirm or correct me.

It's not even necessary because I now see with the new photos that you have a throttle kill switch. That's sufficient to kill the engine by pushing it down fully. That should kill the engine in the way described on my other thread. When you push the throttle "off" the metal part of the throttle should connect with that second wire on the right creating a grounded state. Does it? Conversely, when you throttle up... the connection should be broken and therefore "un-ground" that second wire. Does it?

So as I understand it.. you have a switch that is NOT killing the engine and you wish it did. Just go ahead and hook up that dangling wire to the "isolated kill terminal" so that there will then be a total of three wires.
There's no risk... if it's the correct solution... you're done!
If it somehow stops the engine from starting, let us know and unhook it again in the interim. Cross that bridge later.

When you DO hook it up.... I'd also like to know if all the other safety mechanisms are working as expected.... in other words...

1) If you let go of the handlle... does the engine die when either the auger or the traction is engaged? I believe it should.
2) If you let go of the handle when neither are engaged... does it keep running? I believe it should.
3) when you turn the key off... does it unconditionally die? I believe it should.
4) When you push the throttle all the way off... does it unconditionally die? I believe it should.


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## bad69cat (Nov 30, 2015)

:dizzy:Thank goodness they didint' get convoluted on the wiring in that thing!


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## unknown1 (Dec 13, 2015)

bad69cat said:


> :dizzy:Thank goodness they didint' get convoluted on the wiring in that thing!


Haha.. I'm enjoying trying to figure it all out though.. learning a lot!


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## nt40lanman (Dec 31, 2012)

I've never been a fan of all that "safety wiring". I much prefer the dead-man handles we have now.


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## unknown1 (Dec 13, 2015)

stuart80112 said:


> There's no risk... if it's the correct solution... you're done!
> If it somehow stops the engine from starting, let us know and unhook it again in the interim. Cross that bridge later.


Until you hook that wire back up and test we won't know.... however.... if it somehow prevents the engine from starting then it might mean you have a broken interlock module. We haven't crossed that bridge yet though.

Here's a link for possible future reference.

Interlock Module approx $40:
New Genuine Toro Interlock Module 41 8601 | eBay

Part #12 on Page D
http://www.ereplacementparts.com/to...snowthrower-parts-c-121776_121777_123476.html

If that DOES end up being your problem, at least you'll know why that wire was left dangling in the first place..... someone decided it wasn't worth fixing the module and just disconnected the whole shooting match like Classiccat did earlier in this thread.

You'll then have two options..

1) Order the module to bring things back up to factory specs
2) Just disconnect the darn thing! (got to make your own value judgement)

If you did the latter, you'd be back where you started, but at least you'd know WHY. Ironic if that happens.


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## NRP (Dec 28, 2015)

Time for another update. To answer a question from an earlier post, yes the throttle kill switch does work. I hooked up the interlock module and the third wire to the isolated terminal. No start. I then took apart the back cover of the engine and disconnected the small wire from the magneto. Engine started. Reconnected small wire to magneto and reassembled the engine, and went back to wiring. Upon closer examination I found a damaged terminal and connector for the auger safety switch. Now to back up for a minute to review. When I received this machine it was given to me with an explanation that the engine started fine, but would not shut off with the key. After proving that the auger safety switch was garbage, it dawned on me what happened. Auger safety switch went bad, owner disconnected the entire safety switch system at the interlock module, and started and stopped the machine by using the throttle kill switch. The same owner kept turning the key in the RUN position thinking it had to be that way for the machine to run even though the ignition switch had been disconnected along with the safety system at the interlock module. So, that leaves me with the result of having to make a decision to leave everything disconnected at the interlock module, or find another auger safety switch and replace and reconnect, thereby restoring all safety switches and wiring to working order (in theory). Yes I am right back where I started, but now I know WHY it is this way. :banghead:


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## unknown1 (Dec 13, 2015)

NRP said:


> ...... So, that leaves me with the result of having to make a decision to leave everything disconnected at the interlock module, or find another auger safety switch and replace and reconnect, thereby restoring all safety switches and wiring to working order (in theory). Yes I am right back where I started, but now I know WHY it is this way. :banghead:


Nice work Sherlock. It's all downhill from here. Interesting set of issues... I learned a lot. 

Don't want to complicate things further but.... since the auger switch is "NC normally closed"... you could just short it out, keep the interlock, keep the traction switch, reactivate the key and it would cost nothing to get "half" a solution. Everything back to factory spec except auger detection.

EDIT: That would also be a good way of testing all the OTHER components before bothering to order the auger switch.... could keep it wired that way in the interim (or forever).


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## NRP (Dec 28, 2015)

I learned a lot as well Stuart. I can't thank you enough for all your help. I think you talked me into trying to bypass that auger switch. That would prove all the other safety switches and prove if the auger switch was the only problem this whole time. So far I'm about $150 into this machine. I hope I can get a few years out of it. Thanks again for all your help. I hope a time comes when I can return the favor.


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## unknown1 (Dec 13, 2015)

NRP said:


> I learned a lot as well Stuart. I can't thank you enough for all your help. I think you talked me into trying to bypass that auger switch. That would prove all the other safety switches and prove if the auger switch was the only problem this whole time. So far I'm about $150 into this machine. I hope I can get a few years out of it. Thanks again for all your help. I hope a time comes when I can return the favor.


You are welcome. It was interesting and gave me a reason to put off cracking open two engines that I keep threatening to rebuild. 

Yes you WILL be able to return the favor... I reckon that little trip down the kill switch rabbit hole now qualifies you as one of the Kill-Switch-Safety-Switch Gurus. BTW I cross referenced this thread on my other thread for the next Alice who comes along.

Let us know how the auger bypass works out.


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## bad69cat (Nov 30, 2015)

Yeah - seems a reasonable way to tackle that mess. If you don't mind simplifiying things, I think as long as your careful and have common sense there is no call for all the safety stuff like this? I'd opt for a little permanent by-pass personally. Should be a a nice machine for under $200 no matter how you slice it...... can't complain about that!


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## NRP (Dec 28, 2015)

I took advantage of the mild weather today and finished up my project. The bypass for the auger switch worked as you said Stuart. I reconnected the interlock module and away it went, with all other safety's and key switch apparently working fine.. I decided to leave it as-is after that. If another safety switch goes bad, I'm just going to disconnect the interlock module again. I will be the only user of this machine, and as bad69cat mentioned, a little common sense goes a long way. After the wiring was done, I tuned the new carburetor, changed the oil, and put it back into service! Now I just need snow. :smiley-gen125:


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## unknown1 (Dec 13, 2015)

NRP said:


> I took advantage of the mild weather today and finished up my project. The bypass for the auger switch worked as you said Stuart. I reconnected the interlock module and away it went, with all other safety's and key switch apparently working fine.. I decided to leave it as-is after that. If another safety switch goes bad, I'm just going to disconnect the interlock module again. I will be the only user of this machine, and as bad69cat mentioned, a little common sense goes a long way. After the wiring was done, I tuned the new carburetor, changed the oil, and put it back into service! Now I just need snow. :smiley-gen125:


All's well that ends well.... and for zero dollars... nice!


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