Jump to content
Woodsman

Tearing my hair (and the wires) out.

Recommended Posts

Hi Guys,

A few weeks ago, I had an electrical issue with my machine. The wiring at the switch was all melted,  along with the points themselves being a charred mess. One at a time, I rewired any suspicious wires and installed new points and condensor. Ignition goes to + on the coil, with points and condensor on the - side. After all this I still had a no-spark situation. I started to look at the ignition switch and ended up breaking it in the process. I replaced it with a 92-6785 and wired it to some instructions I found on this site. This is a points tractor and I used the M prong on the switch for this connection. My coil was loose at the top and leaking so I replaced it with a new one. So here's my problem: I'm still at a no spark and found that even when the breaker points are open, I have continuity between the two sides. Unplugging the lead to the coil resolves the continuity, but of course now I don't have voltage. This situation occurs with and without the positive terminal on the battery connected. 

 I now turn to the professionals and ask for guidance. Thanks in advance for any help!

John

  • Like 1

Share this post


Link to post
Share on other sites

Your new ignition switch is for "M"agnito ignition.  You have no power to the points.

You need switch for points ignition.

Share this post


Link to post
Share on other sites

If you have a battery ignition system you need a switch with a "B" terminal, not an "M". Have you downloaded the owner manual with a wiring diagram.

Share this post


Link to post
Share on other sites

Thanks for the replies. I had wondered about the M pole on the switch but had the same markings on the original switch. It turned out to be the one I broke off, as it was burned and corroded.

I've been unable to find the manual on this tractor and have been referencing a C-160 schematic instead. 

Share this post


Link to post
Share on other sites

What year and model are you working on?

Share this post


Link to post
Share on other sites

Most switches will have a "B" terminal for the Battery but what you need to be there for your battery ignition engine is an "I" for Ignition.

  • Like 1

Share this post


Link to post
Share on other sites

Thanks for the schematic. After looking deep in my files it was the one I was using. I'm still puzzled by the switch, though. The manual is missing the page with original part number for the cylinder and the 92-6785 I purchased has the exact same markings as the old ignition.

Share this post


Link to post
Share on other sites

Should be a 5 pin switch  Labels B=battery   I=Ignition  S=starter  R=regulator  A =accessory

 

You can get switches at Loews, Home Depot TSC  just make sure it has an I terminal

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, Woodsman said:

Thanks for the schematic. After looking deep in my files it was the one I was using. I'm still puzzled by the switch, though. The manual is missing the page with original part number for the cylinder and the 92-6785 I purchased has the exact same markings as the old ignition.

Did the tractor work with the "old" switch?

Share this post


Link to post
Share on other sites

Yes the old switch was original and worked well until I broke it. It had all the same markings on the polls as the new switch. 

This is on a 1973 16 Auto.

Share this post


Link to post
Share on other sites
7 minutes ago, Woodsman said:

Yes the old switch was original and worked well until I broke it. It had all the same markings on the polls as the new switch. 

This is on a 1973 16 Auto.

If that is absolutely true then something has been hacked over the years. Can you post a couple pictures of your motor?? and teh switches old an new??

Edited by pfrederi
  • Like 2

Share this post


Link to post
Share on other sites

I cannot see anything on teh old switch...however just because the pin pattern is the same doesn't mean it is the same switch. Are you  reading the letter stamped into the terminal or going by a diagram???

I note the upper right terminal on the old switch seems to be missing...That could have been a "I" terminal not an M.  Where di you get the new witch from??

  • Like 1

Share this post


Link to post
Share on other sites

The old switch did have an M on the missing blade. I'd marked the side of the cylinder with a sharpie for all blades before I broke the M off.  I picked up the new switch off eBay from a reputable Toro dealer. It came in a sealed Toro package.

My test light indicates I have it connected properly, yet I keep getting continuity between the open points when it's all together.

Im about ready to try a simple hotwire to see if the problem persists.

Share this post


Link to post
Share on other sites

Take an ohm meter or a continuity tester and see if the broken tab reads as a dead short to the body of the ignition switch. If it is a Mag. switch it will, that is how it shuts off the engine. I would guess it will not read to ground. However, if you turn the key it will probably have continuity to the "B" terminal.

  • Like 1

Share this post


Link to post
Share on other sites

you need the 3rd or 5th switch down from the top on this link. The difference between the two is the mounting hole size. 9/16 or 5/8.

http://www.psep.biz/store/toro_mower_electrical_parts.htm

 

The wires to the switch will need to be located to the correct terminals

 

That switch (part number 92-6785) you are using is definitely for Magneto type ignition.

 

So there has to be a reason the coil and wires fried to begin with. If that first switch did indeed have a "M", was there a separate toggle switch wired for the ignition? The symptoms you described in your first post are like the ignition switch was left on for a long period of time. Was there any previous owner wiring done to that old switch?

 

If you want to "jump it" run a wire from the + side of the battery directly to the + side of the coil and disconnect the old one from the coil. Turn the key to start it. Shut down by pulling the jump wire from the battery or use full choke.

 

 

Edited by wallfish

Share this post


Link to post
Share on other sites

The ignition on this tractor has the start, run, & run 2 position. When it's in Run 2, you can activate the PTO and lights with separate toggle switches. It's all stock with no modifications. The connections on the old cylinder were sketchy for some time.  I'd also had a problem when trying to crank from TDC and that may have heated things up. It's also possible I may have caused the melt down when I left the battery charger on for too long. I can't recall if I left the key on but I do know it will burn points so I have to wonder. I tried the suggested continuity test and none of the poles will ground out on the base on either cylinder. However, I did find a couple of differences between the two cylinders. In the run position, the old runs with A+B but the new cylinder runs A+B+M. Position 2 (PTO & lights) on the old is B+G and A+M but on the new one all four are continuous.

 You guys have all been great and I really appreciate all the assistance and time you've taken to reply!

I will post a follow-up when I figure it out.

Share this post


Link to post
Share on other sites

The only frustrating part of all this is yours, the rest of us trying to figure stuff like this out is why we enjoy this site. Eventually you'll get going but I'm worried about how much hair you'll still have! I wouldn't be surprised if you end up looking like a Chemo patient by the time it gets running.:ychain:

 

 

  • Like 1

Share this post


Link to post
Share on other sites

Woodsman,   All you need is the correct switch!   The "M" terminal goes to ground inside the switch.  There's no need for that on a tractor with points and coil.  Unless you want to start a fire!   Get the switch for points ignition.  So the old switch was for magneto ignition .... you don't have magneto ignition.  Just forget you ever saw that switch.  Get a switch with B, S, I, A, and R.    Simply put.....    

a wire from the battery "+" terminal to the "B" on the switch,

a wire from the "S" term on the sw to the small term on the solenoid,

a wire from the "I" term on the sw to the "+" on the ign coil,

a wire from the "A" term on the sw to the light switch,

a wire from the "R" term on the sw to the "B+" term on the regulator.

Turn the key and off you go!

You might want to add a few safety switches and fuses.

Here's a pic of the 2 switches.

IMG_0903 (800x600).jpg

Look at that... the switch on the left for magneto ignition has a terminal stamped "M" where the "G" terminal should be.

And the stamp on the terminal in the "M" position has a "G" stamped into it.   I guess you can't go by terminal markings!

BUT you do need a switch with an "I" terminal.

 

 

 

 

  • Like 2

Share this post


Link to post
Share on other sites

I just noticed something .... neither of your switches have a "ground" connection.

Look for markings on the terminal plate, not the terminals themselves.

I think you may have the correct switch!

See the left switch.

IMG_0903 (800x600).jpg

Share this post


Link to post
Share on other sites

So one reason I don't believe the 92-6785 switch Woodsman has is correct, from this Partstree page for the applications of that switch part number. http://www.partstree.com/parts/toro/parts/92-6785/

All of those tractors listed are magneto ignition engines. Guess there must be a typo somewhere?????

 

Another reason is the picture of the new 92-6785 switch posted by Woodsman does not match the switch terminals in the demystification link picture Gary posted, which does show the correct terminals the correct switch should have.

92-6785.jpg

 

Mystified!

 

 

For a quick solution until you can get a new correct switch, pry the edge of the lip up around the terminal plates to remove them. If the old switch needs cleaning, now is the time. Do the same to both switches and swap the terminal plates of the switches keeping the position of the terminals the same. Then tap the lip back down to hold it back together. Nothing to loose since you need a new switch anyway!. I have opened them up numerous times to clean contacts inside when a switch fails and there's really not much to it. Just go slow when opening them so the springs don't get lost. If successful, you won't need to buy another new switch and you are right back to using your original switch so there is no question about the right switch any more.

Share this post


Link to post
Share on other sites

The switch on the right N3PUY posted looks like the 103990 5-terminal 3-position key switch. The 2nd screen shot is the better picture.

 

I only looked at one of the wiring diagrams for a 2002 model 268-H that also uses the 92-6785 switch and it has magneto ignition as stated by Wallfish. But it also has a kill relay powered by the "I" terminal of the battery ignition switch which opens the relay contacts so the motor will run. Ignition turned OFF and the contacts close on a ground contact.

 

Garry

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×