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sovereign Trans. Interlock switch


tripleguy

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My Sovereign transmission interlock started acting up today (when I was about 1/2 done blowing snow). When I'd move the hydro lever forward or reverse, it would cause the engine to die. I needed to clear my car parked in the garage so I rocked it back and forth allowing me to creep ahead, albeit slowly. Is there any way to bypass this switch so I can move the tractor off the driveway until I can get another on installed? Switch is located on the right side of the frame, correct?  Incidentally, my ignition switch broke today too - it separated in half!! Not sure how that happened but I also need to get one of those.

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The transmission interlock should only affect the ability to start, not run.  Once running, that interlock should have no affect.  Your issue seems likely related to the ignition switch issue I would think.  Others with better knowledge may chime in and tell me I'm crazy.  (It would not be the first time I have been described as such)

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I'm guessing your Sovereign is a newer model with the "interlock module".  

It might be related to your ignition switch issue as Brett stated above, but I'd put my $$$ on the interlock module.  Or it could be the "operator present" switch.  If you're not "in the seat" the engine will die if the tranny lever isn't in neutral OR the PTO is engaged.    Might be as simple as the wire to the seat switch came loose.

2 hours ago, tripleguy said:

I needed to clear my car parked in the garage so I rocked it back and forth allowing me to creep ahead, albeit slowly.

The above statement is a bit confusing - were you still blowing snow while rocking back and forth, or just getting the tractor to move while the engine shutdown (and then moved the hydro lever back to neutral so the engine rev'd backup?

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Thanks for the replies. Yes, I wasn't blowing but rocked the hydro lever from forward back to neutral back to forward just to get it to move a few feet. What's weird is after I moved it to where I needed it seemed to clear up and run OK again. I'll check the operator present switch. It's been removed and there is a jumper in place. My Sovereign is newer - 1990 I believe. Do you know what part # the interlock module is and where it's located?

Edited by tripleguy
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Hopefully the operator present jumper is loose or not making good contact at all times.  Spray it with some CRC 2-26 electrical contact spray which should help clean the contact area and resist water.  

On 1/28/2019 at 10:04 PM, tripleguy said:

Do you know what part # the interlock module is and where it's located?

 The interlock module is part#  1707755 - and, IMO, way to expensive to buy new. 

It's located behind the battery, attached to the side of the dash tower (circled in white behind the circuit breaker):

IMG_8329b.thumb.JPG.819d95a7ae3ea96ca3221d260d297070.JPG

The module comes with a 6 connector pig tail; it can be seen here unconnected and bolted in a different location (I relocated it my Command installs):

IMG_8394b.thumb.JPG.d2966f73d80fe25841108cc3e8ba5af4.JPG

 

Edited by PhanDad
Added "behind the circuit breaker" for clarity
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Ya know, I've thought I am pretty familiar with the 7100 series tractors, down to just about the last nut and bolt.  I haven't had any that were the last of the models that had electrical issues.  I never knew there was an ignition module on these.  Must be very late in the run.  Learn something new every day.  Thanks Bill.

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@Brettw

Only the last 7100 series tractors had interlock modules as can be seen in these wiring diagrams from the Sovereign Repair Manual:

image.thumb.png.190dd0f3c2ba129d6caf92146b9d0fd8.png

image.thumb.png.6321aa8e8e57a3bfad401c79cfb002be.png

The 17GTH-L (which I consider a 7100 series tractor) also used the interlock module - same wiring as the 7117).

And since you plan to put the CH20 from the welder into a Sov18, you'll get some first hand experience. 

Enjoy! 666

 

 

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Ok, so how does this interlock module actually work? Does it require all the safety switch to "Say Yes" before it lets the starter run, or does it act as an ignition kill?

It looks like the safety switches set up to have to be closed by whatever they are on so current can flow to the solenoid. at least on the older ones.

 thew latest I've rewired was a B-212, and all it had was the gear shift safety switch, so the complexity of later ones I'm not familiar with.

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12 hours ago, GWGAllisfan said:

Ok, so how does this interlock module actually work? Does it require all the safety switch to "Say Yes" before it lets the starter run, or does it act as an ignition kill?

The simple answer is it depends - and what follows may be more than you want to know.  

For the first "generation" of tractors that incorporated the "operator present" feature (seat nanny), the tractor could be started (crank and ignition) just as the older tractors could as long as the tranny was in neutral and the PTO was off (you don't need to be in the seat).  BUT if either the PTO was engaged OR the tranny not in neutral AND the operator isn't in the seat, the engine would die.  From the 17GTH-L operators manual:

5c533655c7c79_17GTHLInterlockOp.thumb.JPG.73a36d98aa1d5d6dad16728e1c4d67bf.JPG

 

This was accomplished by moving the safety switches to the ground side of the starter solenoid control circuit (rather than interrupting +12v supply to the solenoid) AND adding a relay plus a diode for the Kohler engines.     

The "Kohler" wiring diagram from the 1991 Electrics Manual:

5c532d241e139_17GTHLSafetya.thumb.JPG.a082947bc23dee1dd4a535a3b6e502ce.JPG

The red line shows the "cranking" control circuit and the blue line the "operator present" circuit.  As you can see, there's a completed circuit without use of the "operator present" circuit.  

 

But to truly "start" the engine you also need ignition to enable the engine to run.  This is where it's more complicated.  

5c532d1f90d29_17GTHLIgnitiona.thumb.JPG.c0ff86de96d7b32113a591362c8a47c1.JPG

The Kohler engines of this era used a coil ignition so they needed +12 volts to the coil to supply spark.  A relay was introduced into the circuit from the ignition switch to the coil.  The relay is normally open, so it needs to close to allow the ignition coil to be powered.  The solid red line shows the path to ground for the relay control circuit when the operator is present (spark regardless of tranny or PTO switch position).  The dotted red line shows the path to ground if the operator ISN'T present (spark as long as both tranny and PTO switches are closed (safe positions)). 

The diode between the seat switch and the wire from the solenoid to the PTO switch (labeled "blue" on the diagram) prevents shorting of the "start" voltage to ground through the seat switch).

 

The second (and final) "generation" of tractors (Sov 18 and newer) that has the "operator present" feature (seat nanny), the operation is more restricted as described in the operators manual for these tractors:  

5c533b73aeddb_Sov18InterlockOp.thumb.JPG.201ace87c867a23fae9abf348599dd45.JPG

 This was accomplished by adding an interlock module where ground paths for cranking and ignition go through the module.  The wiring diagram:

Command_Igniioin_Kill_Wire.JPG.acf2ba4b4c523db004087c058f148cbd.JPG

PS - What I don't understand is "Test 4" in the above interlock description.  The Sovereign PTO is mechanical so once it's engaged, there's no way to electrically disengage it.  I know with my 75th, before I jumped the seat nanny, the engine would die if you got off the seat with the tranny in neutral and the PTO engaged.  I think the description is from the generic description of Simplicity's other tractors of that era - all use electric PTO's I believe.  The italics note indicates the PTO "disengages" because the engine stops.

 

Edited by PhanDad
added "control circuit" in a couple spots (clarity)
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Installed new ignition switch and checked safety switch jumper under the seat. The jumper did appear to have loosened from the switch wire so I pushed it back in and the tractor started right up. Seemed to run and drive just fine but time will tell. I only drove it back to the garage but it seems to be sorted out for now. Thanks everyone.

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  • 2 years later...

I seem to be having related issues on my agco allis 918h. Looking at all these wiring diagrams in this thread I havent found one that matches exactly. The nearest is the one labeled 1997 electrical info towards the end of thread. I have the safety interlock switch but my ignition switch is different. It has the kohler engine. On mine the ignition switch and harness plug matches the first set of diagrams that do not show an interlock switch. I do not believe anyone has hacked on this thing and the key still has the tag on it from the original dealer. I have removed and tested the seat switch the neutral switch and the pto switch. All of them work. Also the online fuse from positive cable to ammeter is good and I have power from there to the switch.  Im still not able to crank the starter. Now I have power to the starter as it goes straight there from the battery. Back to the ignition switch. With the key off I have power in the red and white wire to the switch. Turn key to run and I have power to the terminal with white/red and red/blue wires. Only those 2. Then in the start position I get power added to the violet wire. That leaves 2 terminals that never get power. So my issue here is being somewhat novice I'm unsure how to test the safety interlock switch itself and or how exactly my ignition switch is supposed to work to test it. I did look up the interlock switch and it is outrageously priced. If that is bad im looking at bypassing it but would prefer to at least have the seat switch operable as my yard has some steep terraces and it'd be nice to not chop my arm off in a rollover. Maybe a long winded thread here but im looking for some more knowledge on what each wire does 

20210323_174414.jpg

20210324_162139.jpg

20210324_162115.jpg

20210324_162109.jpg

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Not sure if my issue relates to the above issues but, I am having an issue on my late model Sovereigns, both now re-powered with Commands, where after I turn the key to start, I get a delayed start. I am told the Kohler starters are very touchy to minimum voltage drop in the safety circuit due to terminal corrosion. I had a similar issue on my Legacy XL and installed the Simplciity relay kit, P/N 1686945SM which is a plug and play. I have ordered two of these same relay kits to install on my Sovereigns.

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3 hours ago, John Belleville said:

I seem to be having related issues on my agco allis 918h. Looking at all these wiring diagrams in this thread I havent found one that matches exactly. The nearest is the one labeled 1997 electrical info towards the end of thread.

Based on the orange wire in the engine connection plug, I believe the wiring diagram at the end of the thread is for your tractor (FYI - if you click on it, it'll get bigger).  It's for an original Kohler Command powered Sovereign.  Another telling feature (as contrasted to the Triad powered Sovereign) is your main +12V battery cable runs directly to the Command mounted solenoid.  It has a pig tail lead that runs to the dash.  It looks like this:  

IMG_4803a.jpg.f7176d2840408384f4ab4a10a18d41bf.jpg

Note the pigtail lead in the above pic doesn't run to where yours does, this pigtail lead was modified for this originally Triad powered Sovereign.  And I suggest @Bill725 gets one of these cables to try before installing another relay - minimum connections - battery post and Command solenoid, nothing in between.   

Your ignition switch functions as it should - matches the ignition switch connection table in the wiring diagram.  The two terminals that don't get power are ground and the magneto "kill" terminals - when the tractor ignition switch is turned to off, the ground connection ( G) is connected to the mag kill terminal (M).  

3 hours ago, John Belleville said:

im looking for some more knowledge on what each wire does 

I recently made this marked up wiring diagram to help describe the interlock functions:

605bd1956f42b_Command_Interlock_Wirew_Keya.JPG.5be1b8aa6aba3b496473a1ded3e8a6b7.JPG

If the interlock module is "bad" it might not be allowing the dash mounted solenoid to close which powers the orange wire I spoke of before to energize the Command starter mounted solenoid (Orange wire becomes a blue wire (and a red wire to carb fuel solenoid) on the other side of the engine connector).  

PS - Your tractor has the older style ignition switch (metal) rather than the newer rubber (plastic?) that is shown in the pics above of my 75th Ann Sovereign.  They have the same functionality.  

 

Edited by PhanDad
Added PS
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1 hour ago, PhanDad said:

Based on the orange wire in the engine connection plug, I believe the wiring diagram at the end of the thread is for your tractor (FYI - if you click on it, it'll get bigger).  It's for an original Kohler Command powered Sovereign.  Another telling feature (as contrasted to the Triad powered Sovereign) is your main +12V battery cable runs directly to the Command mounted solenoid.  It has a pig tail lead that runs to the dash.  It looks like this:  

IMG_4803a.jpg.f7176d2840408384f4ab4a10a18d41bf.jpg

Note the pigtail lead in the above pic doesn't run to where yours does, this pigtail lead was modified for this originally Triad powered Sovereign.  And I suggest @Bill725 gets one of these cables to try before installing another relay - minimum connections - battery post and Command solenoid, nothing in between.   

Your ignition switch functions as it should - matches the ignition switch connection table in the wiring diagram.  The two terminals that don't get power are ground and the magneto "kill" terminals - when the tractor ignition switch is turned to off, the ground connection ( G) is connected to the mag kill terminal (M).  

I recently made this marked up wiring diagram to help describe the interlock functions:

605bd1956f42b_Command_Interlock_Wirew_Keya.JPG.5be1b8aa6aba3b496473a1ded3e8a6b7.JPG

If the interlock module is "bad" it might not be allowing the dash mounted solenoid to close which powers the orange wire I spoke of before to energize the Command starter mounted solenoid (Orange wire becomes a blue wire (and a red wire to carb fuel solenoid) on the other side of the engine connector).  

PhanDad, I have read through your reply a couple times. I think I have the jist of what you said but let me double check 1 thing. The ignition switch in your photo of the "super clean" tractor has a more rectangular plug on it like mine. The diagram shows a round looking plug. But with that said I did check the wire earlier going to the engine. So coming out of the plug on harness next to starter there is a red wire that lights up when I turn the key on. Also can hear something inside the engine click. However when I tested the orange wire or any of the wires on the solenoid none of them had power. So I have power from the 3 poles on ignition switch and power to the red wire going to the engine but none to the blue wire on starter. So at that plug that has red white and orange wire only the red gets power added by turning the key to run. Nothing changes at that location by turning it to start

 

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@PhanDad 

Also to add to my response. I guess it seems to me that it may be apparent that my safety interlock is not working. Odd that I was changing the hydro fluid put the first round of new fluid in and started it to let run a minute and I was going to raise the deck to check something then lowered it back down and shut the mower off. Added another quart of fluid to transmission and 5 minutes after shutting it off nothing. 

If it is in fact the interlock module could I for now just ground the solenoid at the wire you highlighted purple? 

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1 hour ago, John Belleville said:

The ignition switch in your photo of the "super clean" tractor has a more rectangular plug on it like mine. The diagram shows a round looking plug.

The plugs are the same, and the wiring basically the same.  Pics of both switches (mine dirty as received before my Command Re-Install and some rewiring:

605bf56c5982a_BellevillesIgnitionswitch.jpg.378a6c358a8b053f624b245b500a6a7e.jpgIMG_4682b.jpg.43a26a02fb46be0b13e4f101bad40644.jpg

Your plug is rotated slightly counterclockwise compared to mine.  Wire colors are almost the same and location/function are identical.  The diagram is schematic, not actual.  The above pics match the "back view of switch" schematic.  Top is the "start" wire, or in your case 2 wires (more on this later),  3 o'clock wire is the +12V from the battery, 4 o'clock wire the ground connection.  

My tractor has the older, single solenoid wiring since the Triad didn't need the main +12V power lead directly from the battery.  The Command does.  So Simplicities wiring solution was to keep all the safety switch wiring the same and "adjust" the "start" wiring.  So your tractor has two wires from the "S" terminal and they both go to the dash solenoid.  The green wire is the typical "energize" solenoid wire that delivers +12V to the coil of the solenoid; if the other side of the coil is grounded, the solenoid engages.  The yellow wire is what has to be connected to ground.  You can see from the wiring diagram diagram the path to ground is complicated, it goes through the PTO and Trans safety switches, then to the interlock module and if everything is OK, the dash solenoid energizes.  The second wire from the "S" terminal, the blue wire, is connected to the supply terminal of the load side of the dash solenoid (normally the main +12V battery cable is connected there).  When the dash solenoid coil energizes, it connects the load side terminals and the orange wire (load side out) has +12V to energize the starter mounted solenoid.  

So....

1 hour ago, John Belleville said:

So coming out of the plug on harness next to starter there is a red wire that lights up when I turn the key on. Also can hear something inside the engine click

This red wire at the engine connector is connected to the "L" ignition terminal in both the "start" and "run" positions.  In the "start" position it supplies battery voltage to the fuel solenoid in the carb.  This is the click your hear.

1 hour ago, John Belleville said:

However when I tested the orange wire or any of the wires on the solenoid none of them had power.

Since you only have accessible wiring to 2 terminals of the engine mounted solenoid, you must be describing the dash mounted solenoid.   

On the dash mounted solenoid, with the ignition switch in the "start" position, there should be +12V on both the control and load side supply terminals (green and blue wires respectively).  If there isn't, then there's a problem with the connector to the ignition switch "S" terminal or the wiring.  If your getting +12V on both, temporarily connect the control side output side (yellow wire) to ground.  This will bypass all the safeties and the tractor should turn over (orange wire energized).  

 

Edited by PhanDad
Revised last solenoid section
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17 minutes ago, John Belleville said:

If it is in fact the interlock module could I for now just ground the solenoid at the wire you highlighted purple? 

As I stated above, to bypass the interlock module for starting (cranking is a better description), you would ground the yellow wire side of the the dash solenoid (highlighted in blue, not purple) - it's a push on connector at the top of the dash solenoid, not the most convenient to get to.  Or if you want to keep the Trans and PTO safeties in the circuit,  temporarily ground the tan wire side of the PTO safety switch.  

But you need to get power to both "supply" side terminals of the dash solenoid in the "start" position.  That sounds like it's the problem based on your earlier comments.  

All the above is to get the engine to crank.  The interlock module is also connected to the mag kill circuit.  So if the modules bad, sometimes the engine will crank, but the ignition is grounded so it won't start.  Hopefully that's not the case.  

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Throw that pos interlock module out all together and wore it like a 7116. I had I had a different issue with my Agco1920 . Was interlock module. Based on cost of used one and new one I was like flip that pos. We do Command conversions on 7100 series all the time and don't need it. So I studied my wire diagram. Purchased new neutral switches cause I broke them and wired all the safety's in line with the ignition switch and got rid of the second solenoid on my Agco1920. Problem solved permanently. Yes it cost me about 100.00 but I made a few mistakes and didn't need the wiring I purchased which isn't cheap. My seat nanny is permanently gone and the seat light now functions as an ignition switch confirmation light which tells me I have a safety issue or solenoid starter problem. 

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@PhanDad 

Also to add to my response. I guess it seems to me that it may be apparent that my safety interlock is not working. Odd that I was changing the hydro fluid put the first round of new fluid in and started it to let run a minute and I was going to raise the deck to check something then lowered it back down and shut the mower off. Added another quart of fluid to transmission and 5 minutes after shutting it off nothing.     

Edit                     @PhanDad so I made a wire to connect the solenoid to a permanent ground. I reconnected the interlock module and it cranked over to start up. Upon further thought I tried it again sitting on the seat and it started right up. Got off the seat and it died even in neutral. But it will run as long as you are on the seat. And it will shut off with key. So does that mean only part of the interlock switch is bad? I'm not sure even with this wiring diagram how the ignition shuts off with a ground wire. Or more so how the ground makes it into the safety switch system as the only ground on the drawing goes from battery to the frame. But anyhow if this is not going to cause any self harm to any components I believe I may leave it this way for now and I at least have the seat switch working. I'll just have to get used to shutting it off every time I get off the seat regardless. 

 

 

Edited by John Belleville
Just a separation between steps
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16 hours ago, John Belleville said:

I'm not sure even with this wiring diagram how the ignition shuts off with a ground wire.

The magneto makes a spark when the points (or electronic module) open the primary mag circuit.  When you turn the ignition key to "off", the "G" and "M" terminals are connected and the points can no longer break the circuit.  The ignition switch functions as the "Stop Switch" in this MegaFire Ignition module instruction sheet:

MegaFire_Wiring4.jpg.9c7fbebd15144c0497ce549a7132a292.jpg

On your Command engine, there isn't an external module or points, everything is built into the ignition coils that are mounted above the flywheel: 

6060a4ceb1624_IgnModule2458445(CH18S).thumb.JPG.bdb9394ea49bdbbc153ab48464165ac2.JPG

The white wire is the "kill" wire; when it's grounded there's no spark.  

The interlock module does the same thing when "unsafe" conditions occur and the interlock module grounds the magneto and kills the engine.  In this version of the same wiring diagram, the thick, emphasized lines represent the ground wiring.  You can follow the path from the main engine ground (center right of diagram) to the interlock module and then to the ignition switch.  Note there's another emphasized wire from the interlock module to the ignition switch "M" terminal - when the safety logic isn't met, the interlock module grounds the "M" terminal just as turning the switch to "off" does. 

The good news is, I'm thinking your interlock module is OK, but there's an issue with the safety switch wiring based on your statement:

17 hours ago, John Belleville said:

I made a wire to connect the solenoid to a permanent ground. I reconnected the interlock module and it cranked over to start up. Upon further thought I tried it again sitting on the seat and it started right up. Got off the seat and it died even in neutral. But it will run as long as you are on the seat.

 

This describes how the safety system works on your tractor:

6060a963e17bf_Sov18InterlockOp.thumb.JPG.931638f222cf24cd255b191204c35d7f.JPG

Since you directly grounded the solenoid, the engine will crank.  BUT note in all tests, the seat switch is involved.  So the interlock module can no longer prevent the engine from cranking, but it can prevent it from firing - which it's doing.  

With the tranny in neutral and the PTO disengaged, you should be able to rise from the seat and the engine should still run (Test 4).  Since you tested both the PTO and tranny switches, I suspect there's a wiring issue.  Check the safety switch wiring for continuity and hopefully find the problem.  

 

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