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Femmefisher

Simplicity sunstar electrical issue, desperatly needing help

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Femmefisher

Hi All, i am new here, and I am here for a reason. I have an old simplicity sun star lawn tractor. i am not sure of a model numer, but it has a 16 hp kohler, with a 44" deck, hydrostatic, Front and rear pto available.

Heres what happened. I had jumpered the seat switch so it didnt shut off the engine while off of the machine, and replaced the key ignition. When I went to start it up, smoke started coming out of the interlock module. It melted. I bought a new IM ($170 cdn!), put it in now I get nothing when i turn the key. No headlights, no sounds.

Also, when i go to start it, i put it into neutral and it goes from 12v down to 8. I had it running when i jump started it across the solenoid, now its not turning over anymore either.

I am quite handy i do own a voltmeter and know how to use it. But this has me stumped.

Any help would be appreciated. Thanks

 

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SmilinSam

Is the keyswitch you put in the correct keyswitch?

I ask because I knew a guy that stuck the wrong type of keyswitch in his tractor and cooked the wiring when he turned ithe key on..

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CTD01

agreed with sam! That key switch has to be the correct one!! If I was you I would download the repair manual for the sunstar. There is a nice troubleshooting guide in there. You may have fries the ignition coil also if that keyswitch is incorrect. https://simpletractors.com/files/file/123-sunstar-repair-manual-early-version/

 

 

Edited by CTD01

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PhanDad

I also agree with the above posters.  

  I believe this is the wiring diagram for your tractor (16HP MFG #1691357):

 

5b48c02df2c98_CrackingCircuit16HP.thumb.JPG.50c50abe85251563b2563905c5528a13.JPG

The "cranking" circuit is highlighted by darker lines.  I was surprised to see the Kohler engines used were magneto ignition models (ground to kill).  Most Kohler single cylinder engines used in Simplicity tractors were coil ignition models, if you bought the "regular" or "most common" replacement "Simplicity Kohler ignition switch" you got one that supplies +12v to the mag in the "start" and "run" positions.  

Here's what a Briggs mag coil looks like when a wrong ignition switch is installed:

Coil_New_Fried2.thumb.jpg.8dc069399caa7b48caeb46e48d4a5730.jpg

Hopefully you didn't fry your new ignition module also.  

 

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Femmefisher

Thanks guys. I did notice that the new ignition swition was missing one position, yet the wiring pins were the same. that could be it indeed. How do I test the ignition coil? Also I, it wont allow me to down load that manual. Can someone email it to me? Not sure if i can post my email address here. Thanks

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puttputt

Doesn't matter if the new switch has the terminals in the same position because that doesn't mean the terminals are going to the same items in the circuit as the old switch. I had the exact same problem. I bought a new switch that had an extra terminal like yours but the rest of the terminals were in the correct orientation so I assumed it was correct. I hooked it up and fried a wire in the same amount of time it took to turn the key on. Thank goodness it was only one wire. Anyhow, I finally got a hold of a proper wiring diagram and discovered that the various items in the circuit were not correct for the terminals on the new switch. Bottom line, get the correct switch from Slimplicity.

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SmilinSam

On the keyswitch. Most all of the keyswitches in lawn & garden tractors anymore are 5 prong switches. Not all 5 prong switches route the power to the same prongs in the different key positions.

There are basically 2 types of 5 prong switches. One is Battery ignition( used on Konhler engines with external coils- K series engines) The other type is magneto ignition( used on most all Briggs engines as well as Kohler M series engines).

Among the Magneto ignition keyswitches, there are a multitude of types among that group- all with 5 prongs..and occasionally a 6th prong. Each of that mutitude routes the power to different prongs in the diffeent key positions.  So...you can see how easy it would be to get the wrong switch if you didnt buy it with the tractor model number from a dealer, or went to install a new switch into a tractor that a previous owner had repowered with a different type of engine.

 

The thing that concerns me is that you put the new module in and tried to start the tractor. If so, you may have already ruined that new expensive module if the keyswitch is wrong.

Edited by SmilinSam

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Femmefisher

Oh no.....well i didnt see smoke, and nothing happened. i take it the interlock module is like a bunch of relay's incased. So to test so I just go top pin to bottom pin all the way down to see if they are open or closed? If I am incorrect please let me know how to test the interlock. Thanks 

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PhanDad
24 minutes ago, Femmefisher said:

i take it the interlock module is like a bunch of relay's incased.

I don't believe so.  It's a mini-circuit board that reads inputs (position of safety switches, etc) and then outputs +12v as permitted by the "safety" logic.  Here's a blowup of the bottom corner of the wiring diagram I posted above:

5b48eed4366c2_CrackingCircuit16HPb.JPG.fd0a68e4c3d631aeda8fbe7bb22a1522.JPG

As to testing the IM, I'm sure Simplicity (and maybe dealers) had a "gizmo" to test them.  Do do it yourself, you'd have to know the "safety logic" and then set the inputs up as required and check the output(s).  I would think the "safety logic" is described in the operating instructions (it is for the Sovereign with IM).   And based on the whole wiring diagram there are also additional switches involved in the "safety logic" - follow the wiring from the "TR START SW" IM module.   

PS - The SunStar wiring is much more complex than a Sovereign.  It even has a "TEST PANEL" connector shown in the wiring diagram just to the left of the IM wiring I show above.  

 

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Femmefisher

OK so, I went to my Local Guy..TY Conways!, and he set me up with the proper switch. Everything looks good lights are on voltage is fine at neutral switch, but still nothing , wont turn over no clicking. :(. Next???????

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SmilinSam

My guess is the new interlock module was fried when you turned the keyswitch on after you installed the module but still using the wrong keyswitch.

However, before you go buy another one, I would-

 

1) have the dealer test the interlock module(if they can)

2) test the starter solenoid

3)test all the safety switches

4)check all the wires in the safety circuit to make sure nothings broke or damaged there

 

Not much else it can be if the battery is up.

 

If you get it to crank over eventually and you dont get any spark, then you are going to have to check the mags on the engine to see if they got fried too. First things first though, get the starter circuit working.

Electrical problems can get expensive fast when components are getting shorted out. I had a new conquest that started cooking regulators. I burned up 2 @$70 each , then took the tractor to a dealer, who in turn burned up 2 more regulators before he finally found the problem.

I feel your pain......

Edited by SmilinSam

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PhanDad
2 hours ago, Femmefisher said:

PhanDad, would you be able to zoom in on the switch and send a pic of that here please and Ty.

5b4aa5438b7ed_CrackingCircuit16HPc.thumb.JPG.15a567e1609e7f5dac0bcdc6b49bb7c1.JPG

Your tractor wiring diagrams are available in the "Downloads" section of the site.  The above is from the 1990 Electrics Manual; the 16HP SunStar might also be available in later Electrics Manuals.  

 

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Femmefisher

Hi GUYS, so some good news, got the engine started by jumping it , yet, i have disconnected the wiring harness from key switch, pto, interlock, clutch, seat, pretty much everything but the solenoid and starter it self. It fired right up. Still tracing a bad wire somewhere. I appreciate you all helping, this site has become very valuable last few days. I am a member now too!!! Looking forward to finding the culprit and sharing my success if and when it happens.

PS, there is a test site on the tractor by the interlock, anyone know how to use it? Is there a modern day reader or something?

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Femmefisher

Ok can anyone PM me on how to get power to the pto and put in a switch, just so I can get my 5 acres mowed??  I take my life in my own hands!!!!

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PhanDad
42 minutes ago, Femmefisher said:

Hi GUYS, so some good news, got the engine started by jumping it

Great news, the mag coils weren't fried.  

 

44 minutes ago, Femmefisher said:

PS, there is a test site on the tractor by the interlock, anyone know how to use it? Is there a modern day reader or something?

Probably dealer test device.  I haven't heard anyone on the site discuss the "test panel" connection.

As I said before, the SunStar wiring seems very complicated.  For the short term, I'd wire it up like the late '70's Sovereigns (Briggs engines with magneto ignition:

16GTHL_Wire7116_NoIM.jpg.1c19855747d50068e23ef69c764773ac.jpg

It's pretty simple: Only "safety" is tractor won't start unless trans in neutral, front and rear PTO's off (start signal from key switch passes thru the 3 "interlock" switches in series; if one is open, the solenoid isn't energized).  Once the tractor is running, the operator is responsible for safety.  I don't think it would be hard to convert to this simple wiring setup and you could use much of the existing wiring.  

 

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PhanDad
1 hour ago, Femmefisher said:

Ok can anyone PM me on how to get power to the pto and put in a switch, just so I can get my 5 acres mowed??  I take my life in my own hands!!!!

Hot wire drawing:

5b4d0c80a2256_CrackingCircuit16HPd.thumb.JPG.089129152e199d9673fcbc1ff93f4b04.JPG

 

NOTE: THIS WILL TAKE ALL SAFETIES OUT OF OPERATION. 

"Red wire" from "start" switch terminal to one side of solenoid coil (if it will reach, you can remove the PTO switch end of the violet wire that goes from the ignition switch to the PTO switch and connect it to the solenoid terminal).  

Ground the other solenoid coil terminal.  

With the above changes, the tractor should crank but may not start since the IM or other switches maybe grounding the magneto.  So you'll have to cut or disconnect the blue wire that goes to the "bottom switch" (not the blue wire that goes to the engine connector) to remove the engine shutdown safeties from functioning.

At the front PTO, ground the all black wire.  

Leave all other wires connected to the new correct ignition switch.  I'm hoping the PTO switch will function.  The IM controls the ground circuit, so by directly grounding the PTO, the IM has been removed from the circuit.  With the ignition switch in the "run" position, after the PTO is direct grounded, you should be able to hear the electric clutch pull in when the PTO switch is used.  If it doesn't, the "red wire" (with new switch) will provide power to the PTO. 

 

Edited by PhanDad
Added possible cut of blue wire (safety mag kill)

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PhanDad
2 hours ago, Femmefisher said:

there is a test site on the tractor by the interlock, anyone know how to use it?

Looking at the wiring to the "test panel":

5b4d0841e77c3_CrackingCircuit16HPTestPanel.JPG.86f9163a3a3b73a5c801588d658dbb2b.JPG

You maybe able to tell where the electrical problem by checking voltage at the various pins.

For Example:

Middle Row Right, Pink Wire is +12v from battery (circuit breaker not open)

Bottom Row Left, Violet Wire should have +12v  when ignition switch is in "start" position.

 

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Femmefisher

SO, what I'm thinking is if i Take out the whole damn wiring harness, run a fused switch to PTO purple directly from the battery, and ground the black. Jump the mower flick the switch and mow away???? 

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PhanDad
1 hour ago, Femmefisher said:

SO, what I'm thinking is if i Take out the whole damn wiring harness, run a fused switch to PTO purple directly from the battery, and ground the black. Jump the mower flick the switch and mow away???? 

No, the PTO purple (violet) is the "start" circuit that runs thru the PTO switch (to make sure it's off).  The PTO switch gets power from the black wire that comes from the ignition switch "rectifier" terminal.  

Rather than "run a fused switch to PTO"  black, connect the pink wire from the circuit breaker (downstream side) to the black PTO wire (maybe you can just move the pink wire from the ignition switch terminal to the PTO switch terminal) .

If you do the above, charging system will be removed from the circuit.  The PTO will draw power straight from the battery; when the battery drains down, you'll lose the PTO.  Also, IMO, running an electric PTO with low voltage can cause premature failure.  

If you're happy starting and stopping the engine without using the ignition switch, I'd disconnect the "magneto" and "start" wires from the ignition switch (keeping the "rectifier", "battery", and maybe the "lights" connections) - This would allow the ignition switch to provide power to the PTO (and lights, etc if you leave it wired) AND have the battery charging system working to keep the battery at full voltage.  

BLT video - How to remove wires from connectors:

 

Edited by PhanDad
Added BLT Link

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CTD01

That sunstar manual has testing the interlock module without the factory tool. I works well. I had an issue with mine and used the test in the book.

Edited by CTD01

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