1990 312-8 PTO/NEUTRAL SWITCH

["Manic-Mechanic" 1,195]

I have been looking at my Run circuit as the tractor should run while I’m off the seat.

There is a double set of pto switches isn’t one designed to maintain a run circuit while seat is empty? Regardless of the position of the seat switch?

[gwest_ca-(File Mod) 11,113]

Magneto ignitions are self-powered.

The single ignition wire is grounded to shut the ignition off.

With pto OFF the ignition wire to the pto is not connected to anything so the ignition wire can not get to ground - ignition works

With the pto ON the ignition wire is connected to the seat switch.

With operator in the seat the seat switch is open so the ignition wire can not get to ground - ignition works

With no operator in the seat the seat switch is closed which grounds the ignition - ignition is shut off

 

Garry

["Manic-Mechanic" 1,195]

So the seat switch cannot be effected by pto switch? Or should the engine stall if the seat switch trips?

Edited March 22, 2021 by oldman

[gwest_ca-(File Mod) 11,113]

38 minutes ago, oldman said:

No, the two switches at the pto, how does the engine run with nobody on the seat and pto off?

One pto switch controls the ignition.

The 2nd pto switch controls the starter circuit.

 

Copied from my previous post

With pto OFF the ignition wire to the pto switch is not connected to anything so the ignition wire can not get to ground - ignition works

Seat switch has no control over the ignition with pto OFF.

Adding

Seat switch has all the control over the ignition with the pto ON

 

Garry

["Manic-Mechanic" 1,195]

Ok, so no the brake/seat circuit cannot be effected by the two switches at the pto.

There leaves my pc board plug & harness, not the board just plug

Never had a circuit behave like this and it gets me pissed not having it correct! I have a thorough grasp on the pto set up and the principal of the brake/seat circuits, but why their crossed, “stumped”

Maybe someone local can help as well, Lincoln maybe?

Edited March 22, 2021 by oldman

["Manic-Mechanic" 1,195]

33 minutes ago, gwest_ca said:

One pto switch controls the ignition.

The 2nd pto switch controls the starter circuit.

 

Copied from my previous post

With pto OFF the ignition wire to the pto switch is not connected to anything so the ignition wire can not get to ground - ignition works

Seat switch has no control over the ignition with pto OFF.

Adding

Seat switch has all the control over the ignition with the pto ON

 

Garry

So , there-in lies my issue, the pto switch or maybe even in the ignition plug itself? Can you come to Chambersburg and fix this? Lol!

[gwest_ca-(File Mod) 11,113]

The brake has nothing to do with the ignition or start either. The brake switch just connects to turn the light on to tell the operator the parking brake is on.

 

The tractor should operate normally without idiot lights so leave the circuit board out of the circuit/connector and see if the pto and seat switches work correctly.

With pto OFF start and run tractor. It should work with or without operator in seat.

With tractor still running sit on seat and then engage pto.  Tractor should keep running.

Lift off the seat or fall out of the seat and engine should quit.

Let us know what you find.

 

With the circuit board removed it just may fix things. If there is a board failure I do not know how it would affect the tractor operation.

 

Garry

 

I added a line to my previous post.

["Manic-Mechanic" 1,195]

Everything functions correctly except the brake/seat, they appear reversed, don’t know how? Thing is, can I run it this way and just go with it or leave it unplugged?

The PTO feature is nice to have an indicator? I wonder now, the black from the brake switch, somehow got mixed up with the black from the seat switch?

Edited March 23, 2021 by oldman

[gwest_ca-(File Mod) 11,113]

20 minutes ago, oldman said:

Everything functions correctly except the brake/seat, they appear reversed, don’t know how?

 

Thing is, can I run it this way and just go with it or leave it unplugged?

Sure can. That is how they were before we had the lights.

 

 

Quote

The PTO feature is nice to have an indicator? I wonder now, the black from the brake switch, somehow got mixed up with the black from the seat switch?

Diagram shows a pink (12 volt with key in RUN) and a white going to the circuit board at the brake switch. No black. The circuit board is looking for 12 volts to turn the brake light on.

Toro has been very good at reserving black wires for ground circuits.

 

Garry

["Manic-Mechanic" 1,195]

I have been all through this schematic and trying to find a spot where the pink could have crossed a black energizing the seat circuit, rather than the brake as it should be.

Maybe one day it'll come to me? Can I safely run this light display as is? I mean it's been this way now probably decade or better! Or just simply unplug it? I won't keep "throwing parts at it!"

["Manic-Mechanic" 1,195]

Say,

  I found the guide for the 1986 312-8 and the pc board on it has 7 & 8 reversed. I could have an older pc board. I also picked up a replacement and now must check an see if there is a difference between the two boards, I believe there is.

 

 

 

 

1986-1988 board #110999 replaced by #115207

Used on 200-Series models YT-12A, 211-5 and 211-6

Used on 300 and 400-Series Kohler single cylinder models

 

1986-1987 board #111000 replaced by #115207

Used on 400-Series Kohler twin cylinder models

 

19?? board #111377 replaced by #115207

Can't find the application

 

1988 board #111390 replaced by #115207

Used on Kawasaki powered 200-Series

 

1989-1990 board #115207

Used on 300-Series Kohler single cylinder models

 

1989-1990 board #114825 replaced by #115207

Used on Kohler single cylinder and twin cylinder 300-Series export models

1991-1997 board #114825 replaced by #115207

Used on 300-Series Kohler single cylinder models

 

There is a huge difference in the pin locations for seat/brake on the 1986 vs 1990, exact opposite in fact.

Edited March 23, 2021 by oldman

[gwest_ca-(File Mod) 11,113]

Wiring is different because the 1986 312-8 used battery powered ignition. - 12 volts powers the ignition coil and the safety switches control the 12 volts.

1990 uses magneto ignition so the safety switches control the ignition ground.

 

At one time we determined all the circuit boards are interchangeable.

 

Garry

[KAA 1973 71]

I was having issues with the pto switches last month, searching here I ran across a  post explaining the two pto switches so I copied it for future reference.

 

 

 

The seat switch is there to shut down the engine if the half of the PTO Switch that connects to it is in the PTO ON position and no one is in the seat, if your PTO is OFF the seat switch will do nothing. The dark blue wire form the PTO switch will join the wire going to your magneto.

The other half of the PTO Switch will prevent the starter from operating if the PTO is ON, if your PTO is OFF the switch will do nothing. If you have a clutch switch the purple wire from this half of the PTO switch will go to the clutch switch, if you don't have a clutch switch it will go directly to the small terminal on the Solenoid. You don't have an engine low oil switch so the low oil relay is not going to be used.

The drawing below should be helpful. Both switches have wires that would go to the "idiot lights" for Seat and PTO (not shown on the 310 drawing) but you don't need them, just cut them off.

["Manic-Mechanic" 1,195]

All of this is really great and totally appreciated. However, there is no resolve to the ongoing issue. The pto switch that connects the dark blue to orange must be affecting the circuit as she will not keep running if you lift from the seat with pto off.

I tested both the micro switches at the pto and they function. So the why as to the error at the light panel is puzzling me.

["Manic-Mechanic" 1,195]

1 hour ago, gwest_ca said:

Wiring is different because the 1986 312-8 used battery powered ignition. - 12 volts powers the ignition coil and the safety switches control the 12 volts.

1990 uses magneto ignition so the safety switches control the ignition ground.

 

At one time we determined all the circuit boards are interchangeable.

 

Garry

I thought because 7 & 8 were reversed in the 1986 schematic, that I had found something! The way she won’t stay running off the seat with the pto off must have something to do with this issue.

However, I cannot spend more time on this as I am stabbing in the dark, neglecting other things greatly!

["Manic-Mechanic" 1,195]

2 hours ago, KAA 1973 said:

I was having issues with the pto switches last month, searching here I ran across a  post explaining the two pto switches so I copied it for future reference.

 

 

 

The seat switch is there to shut down the engine if the half of the PTO Switch that connects to it is in the PTO ON position and no one is in the seat, if your PTO is OFF the seat switch will do nothing. The dark blue wire form the PTO switch will join the wire going to your magneto.

The other half of the PTO Switch will prevent the starter from operating if the PTO is ON, if your PTO is OFF the switch will do nothing. If you have a clutch switch the purple wire from this half of the PTO switch will go to the clutch switch, if you don't have a clutch switch it will go directly to the small terminal on the Solenoid. You don't have an engine low oil switch so the low oil relay is not going to be used.

The drawing below should be helpful. Both switches have wires that would go to the "idiot lights" for Seat and PTO (not shown on the 310 drawing) but you don't need them, just cut them off.

Ok, so-if the two wires going to the clutch switch got reversed, could this be the issue? Secondly, there is an oil sensor, relay in an active circuit.

The two switches on the schematic show the transfers, on the brake circuit it shows both paths. On the seat it joins dark blue. So, NC/NO should be easy enough, if in doubt swap the plugs

Edited March 23, 2021 by oldman

["Manic-Mechanic" 1,195]

Ok, the two circuits at the pto, if the plugs had gotten switched around, stands to reason this could be an issue.

which circuit is on top in the pto two switch set up? Right now the dark blue and orange wires are landing on the top switch, may just swap them. I cannot see which goes on top in the schematic

[gwest_ca-(File Mod) 11,113]

Both switches are identical.

Orange and blue can be reversed and still be correct if circuit board is not used.

Same with purple and tan if circuit board is not used.

 

Garry 

["Manic-Mechanic" 1,195]

16 minutes ago, gwest_ca said:

Both switches are identical.

Orange and blue can be reversed and still be correct if circuit board is not used.

Same with purple and tan if circuit board is not used.

 

Garry 

I. Know the switches are identical but the plugs are not wired the same. This is using the board/light panel. I am going to just swap them and see.

Edited March 23, 2021 by oldman

[gwest_ca-(File Mod) 11,113]

Can you not see the illustration I posted?

 

Ignition pto switch - Orange goes to Common terminal - Blue goes to NC (Normally closed) terminal

 

Starter pto switch - Tan goes to Common terminal - Purple goes to NO (Normally open) terminal

 

Garry

 

Adding

It does not mater which connector goes on which switch because the switches are both the same.

The only way it can be messed up if someone removed the wires from the connector and did not put them back in the same locations.

 

When did the problem start?

Have you always owned the tractor?

["Manic-Mechanic" 1,195]

3 hours ago, gwest_ca said:

Can you not see the illustration I posted?

 

Ignition pto switch - Orange goes to Common terminal - Blue goes to NC (Normally closed) terminal

 

Starter pto switch - Tan goes to Common terminal - Purple goes to NO (Normally open) terminal

 

Garry

 

Adding

It does not mater which connector goes on which switch because the switches are both the same.

The only way it can be messed up if someone removed the wires from the connector and did not put them back in the same locations.

 

When did the problem start?

Have you always owned the tractor?

Say,

  If I rotate the pto switches the tractor will not start. Also my brake switch wires are red & white.

I’ve tried every configuration and it’ll run the way it is or totally unplug the pc and have no “bling”

”replace the harness”

Edited March 23, 2021 by oldman

[KAA 1973 71]

This is how my switches were wired after replacing them and the tractor runs with no issues

Don't forget about the clutch switch, the pink wire on one of the PTO switches comes from the clutch switch.

Also the PTO switches were confusing to me because no wiring diagram shows the 2 black wires on them or where they go.

 

Edited March 24, 2021 by KAA 1973

[gwest_ca-(File Mod) 11,113]

37 minutes ago, KAA 1973 said:

This is how my switches were wired after replacing them and the tractor runs with no issues

Don't forget about the clutch switch, the pink wire on one of the PTO switches comes from the clutch switch.

Also the PTO switches were confusing to me because no wiring diagram shows the 2 black wires on them or where they go.

 

What model and year is this tractor?

Looks like the black wires with white stripes are piggy-backed on the tan and a wire that is badly faded on the ignition pto switch. There are double wires on the models with battery ignition to control the circuit board.

 

Garry

[Damien Walker 246]

Just my two penneth for what it is worth.....but your story is very familiar. My relevant tractor here is a 518H that I have just completely rebuilt after the PO badly neglected it. I concur with all the advice about wire colours and the purpose of the two pto switches in conjunction with the seat switch etc and I had very similar problems.

 

I made progress by drawing out the specific parts of the interlock wiring into a more logical fashion (e.g draw out the ignition wiring showing one pto switch and the seat switch).  This helped confirm a number of intermittant gremlins: one minute the switches  were working, then they weren't. At one point I had only 3.7V and the list goes on!

 

Here's what fixed it for me:

1) Broken connectors in the main to engine harness plug. (Poor quality,  not corrosion). I replaced the whole connector.

2) Weird ignition switch action caused by historical water ingress. This was so bad, I was initially convinced I had swapped wires  in the main connector. New ignition switch.

3) Intermittents on the pto switches. (Poor quality again unfortunately, the 3/16"(?) blade terminals which are split down the middle, had collapsed and so were loose) I bought new switches with 1/4" blades (not WH parts) and fitted new females on the wiring loom without the unitary connector body. Whilst this connector body is good for maintaining the orientation during servicing, it was part of my problem....it kept pulling the common connector terminal off.

 

With those items improved, I then had stable performance which enabled me to trace a fault (my mistake) in the seat switch wiring. It's a new seat and it has the seat switch built into the seat. The original is a changeover switch to implement the dashboard warning light but the new switch is SPST so I used it to drive a changeover relay. I needed to use an ignition switched live to feed the relay coil but picked up on the accessory terminal by accident....which is switched off when you engage the starter motor! Needless to say that caused some odd effects with my interlock arrangement.

 

It sounds as though your pto switches were also part of your problem. Mine is all running fine now.....other than the fuel gauge which clearly has an intermittant connection internally.

 

 

[Handy Don 12,553]

7 minutes ago, Damien Walker said:

My relevant tractor here is a 518H

Big difference is that I believe Oldman's unit is magneto-fired while the P218 is battery driven. Fundamental difference is that on magneto you ground the coil to stop the motor and on battery, you open the circuit. Very different switching requirements.