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tripleguy

sovereign Trans. Interlock switch

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tripleguy

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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Brettw

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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PhanDad

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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tripleguy

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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PhanDad

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.  

12 hours ago, 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):

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

 

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Brettw

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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PhanDad

@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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GWGAllisfan

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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PhanDad
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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tripleguy

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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