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Hot wiring tractor

hot wiring

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#1 BrokenTractor OFFLINE  

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Posted April 14, 2015 - 01:10 AM

Hello,

 

I have an older tractor about 15HP maybe a 1990 MTD. But the main thing is there are so many wires even with a new battery the tractor refuses to even make a clicking noise upon turning the key.

 

But having said that I wish to just get rid of those wires. And do a simple hot wire for now to see what is what.

 

I have watched some videos on hot wiring including a push button starter and kill switch toggle as a new modification to eliminate all those wires. I don't care about the lights working or not, just want the engine to turn over.

 

The thing that my tractor has that might be an issue is some sort of ground wire with a mini molex connector that plugs directly under the carb bowl. When the tractor did run when you unplugged this wire, the engine shut down.

 

These are some things I have noted that I need to account for:

1. The coil has the spark plug wire and a thin black wire( ground I am guessing )

2. If you look at the starter side of the engine,you see the hot lead ( from  battery ) going to the starter, another red wire for going back to battery ( to charge it ) and then some other wires. The other wires concern me, not knowing what they do.

 

But if I do a simple a very simple connection where I connect say a black 12 gauge 15 amp wire to the new battery (- side ) and on to ground, and then a brand new red 12 gauge wire 15 amp wire (+ side ) to battery going to the starter with all the other wires removed except the spark plug wire, will the starter engage? I don't care about back feeding current right now to re-charge the battery, just whatever the minimum configuration is needed to figure what the problem is. In 2014 I had to take the kill switch out which sits under the seat because this was a problem then. After that it worked fine for a while. But it seems there are so many safety features, gauges, lights etc which I don't need is messing up all the electrical to the point where nothing works.

 

So will this work?

 

Thanks,

James P.



#2 MH81 ONLINE  

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Posted April 14, 2015 - 07:10 AM

Due to the liability issues, most guys are hesitant to give instructions on removing/bypassing safety switches.

Just for testing purposes, My first steps would be to take off the mower belt, block the rear end up, disconnect the spark plug wire and then build a short momentary test jumper on the solenoid from the wire from the battery to the activating post.
There are a couple configurations of solenoid, so either a picture of yours or do a search for what the pin out on yours would be.
If the engine rolls over, you know the starter and solenoid at least work.
Then I would do this again and check for spark. Use a spark checker. Be prepared to pull the plug wire or pull the choke to shut down the engine if it should start
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#3 BrokenTractor OFFLINE  

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Posted April 14, 2015 - 07:35 AM

Thanks for the reply. That is the other thing, I believe my tractor does not have a traditional looking where you have 2 posts and merely bridging those posts would turn the starter. I could not find that, It seems like it has some sort of intregrated circuit where a

bunch of wires plug into a large molex connector. I will look again for the older type of solenoid, but if I am right about the intregrated circuit then that is way beyond my skill level. Not sure how to proceed.

 

Thanks,

James



#4 KennyP ONLINE  

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Posted April 14, 2015 - 07:49 AM

:wave: Welcome to the forum! Some pics here would be of great help. There is a link in my signature that will show how easy it is to upload them.

On the tractor, this sounds like it may be similar to a mower I had till the rear end locked up. Look under the seat for a long model #. I might be able to find you a wiring diagram with that.



#5 jms180 ONLINE  

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Posted April 14, 2015 - 09:30 AM

:wave: Welcome to the forum! Some pics here would be of great help. There is a link in my signature that will show how easy it is to upload them.

On the tractor, this sounds like it may be similar to a mower I had till the rear end locked up. Look under the seat for a long model #. I might be able to find you a wiring diagram with that.

Kenny is correct. If you could post model number of engine and model of mower someone will find an electrical drawing and help you out with trouble shooting problem.



#6 tater195 ONLINE  

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Posted April 14, 2015 - 10:08 AM

If I remember right, and I probably dont, (I might be thinking early 90's murray) ...they hid the solenoid under the fuel tank. There is a removable panel on one side of the dash tower to access the solenoid.



#7 JDBrian OFFLINE  

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Posted April 14, 2015 - 10:29 AM

If you can find the wiring diagram, you can learn about the tractor by troubleshooting the problem and fixing it. That way you get to keep all the safety features that were designed to protect you.



#8 MH81 ONLINE  

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Posted April 14, 2015 - 10:42 AM

Often times, they hide them down low on the tractor for some reason.
I had one that was buried behind the dash tower on the frame. You should be able to follow the wire from the starter back to it.

#9 KennyP ONLINE  

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Posted April 15, 2015 - 07:26 AM

You will need both Model & Serial to find a manual for it.



#10 WNYTractorTinkerer ONLINE  

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Posted April 15, 2015 - 08:17 AM

The Tractor Model # and Engine Make and Model # are essential for anyone anywhere to give you any useful help BT.  Google the tractor make & Model # and check Tractordata.com and it will usually give you the type/make of engine they used.  Sometimes the engines vary as the years go by so check on the engine's Flywheel shroud for the Model #..  Sometimes stamped into it, sometimes a label..  As Kenny said..  Pictures help a lot too.  Fire back if you need help there since you are a new member..  

 

Ohh-  and BTW-->  Welcome aboard!!


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#11 BrokenTractor OFFLINE  

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Posted April 16, 2015 - 12:48 PM

I was able to upload some pics of the MTD.

 

modelnum
frontright
frontleft

 

I am at the point where I can connect a hot lead right to the starter post and the starter engages BUT the engine only runs for a couple seconds then shuts down.  I can tell you for a fact when the tractor was running fine by merely disconnecting the molex directly underneath the carb would shut the engine down. All of the wires now go no place they are just sitting there.

 

What I need to know is if I disconnect the molex under the carb ( right now it goes no place ) will this make the engine shutdown?

 

I am getting good spark , flywheel turning, what I don't know right now is if the kill switch system is somehow still active or the engine simply refuses to run.

 

Thanks,

Jim



#12 mrmr56 OFFLINE  

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Posted April 16, 2015 - 01:39 PM

You will have to get 12 volts and a ground to the solenoid on the bottom of the carburetor for it to run, otherwise, the fuel flow is interrupted in the carb. Get that accomplished and it SHOULD stay running if it starts otherwise.


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#13 BrokenTractor OFFLINE  

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Posted April 16, 2015 - 02:40 PM

mrmr56,

 

Thanks for the info. The way it is now when I touch the hot wire directly from the battery to the starter post and the engine starts, I then move the 'starter wire' away from the starter and the engine quits. Maybe this is one reason why it quits? My understanding is once the flywheel turns I do not need +12 volts going to the starter anymore. Once I can get it to run for a few minutes then I am going to build it back up to a config that has a key or push button ignition and a kill switch. I am just making sure that any further time spent on this si not a waste of time.

 

Also where you write,"You will have to get 12 volts and a ground to the solenoid on the bottom of the carburetor for it to run"

 

Can I do this. Connect a thin red wire from that molex connector and send it back to the battery and keep it attached for a while. Then take the ground from that molex connector and ground it. Then use the method of touching the starter post with the live wire (#6 gauge ) that originates at the + side of the battery?

 

Thanks,

Jim



#14 BrokenTractor OFFLINE  

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Posted April 16, 2015 - 04:38 PM

mrmr,

 

it worked thanks again!



#15 mrmr56 OFFLINE  

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Posted April 16, 2015 - 05:44 PM

I'm glad you have got it working. Now you can determine what else is wrong with it.
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