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Brettw

Electric clutch wiring, Sunstar

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Brettw
I have a question. It appeared to me the front electric PTO clutch on the Sunstar I am restoring was not working. Upon removing the engine for repairs, I bench tested it with direct power and it works fine. One thin I find odd is the way it is wired. The clutch has two separate wires on it, one coming out each side and running to different wires routed on opposite sides of the engine. Why there wouldn't be a regular two spade plug, I do not know. Anyway, to be sure of operation, the clutch works when these two wires are hooked up, one with power the other a ground. The problem seems to be in the ground wire on the tractor. A continuity test on the power side, when the switches are all on and the seat nanny overridden is fine. But continuity on the ground wire isn't there, and there is an ever so slight and barely perceptible light on the tester when checking the ground wire on the hot circuit. Obviously this is an issue I can trace down. My question is, why does the ground wire run all the way back to a wiring harness and then into the rat's nest? Why wouldn't it just ground with a short wire right up front, or be grounded being bolted right to the engine? This wire must be married to one of the nanny setups and as such this may be the issue? Thanks in advance for any help or insight.

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RickS
Brett, While I have no experience with the Sunstar on my legacy the pto and seat nanny are tied together. If the pto is not engaged and I get off the seat the motor shuts off. If the pto is not engaged and I engage the parking park the motor keeps running when I get off the seat. However if I engage the pto I cannot leave the seat no mater what. It does not matter if the parking brake is engaged or not; if the pto is engaged weight must be applied to the seat at all times or the motor shuts off. Maybe your Sunstar is wired this way. Rick......

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PhanDad
I also have no experience with the Sunstar, but I think Rick is correct. I bet the Sunstar has an "interlock" module and usually those modules "switch" the ground circuit. My Homelite with electric clutch is wired as you suggest. One electric clutch lead is connected to +12v via the PTO switch and the other lead grounded at the engine block via an engine mounting bolt. Wired in this manner, the electric clutch will always turn on and off with the switch (ignition switch "on"), however, the switch has a second set of contacts and the "starter" safety circuit is also connected to the switch. When the PTO switch is "off", the "starter" circuit is closed and when the PTO is "on" the "starter" circuit is open. Wired this way the tractor will not start if the PTO switch is "on", but once started, the electric clutch stays engaged. There is no seat nanny on the Homelite. I'm happy with this setup although it's not as safe as the newer tractors. Another thing with electric clutches is to be sure the ground is a good one and stays that way. Al Eden has mentioned that if the ground is lost or marginal, sometimes the electric clutch, can ground through the crankshaft and that's not a good thing. I check the ground routinely and with it directly wired to the block it's easy to do.

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RayS
quote:
Originally posted by RickS
Brett, While I have no experience with the Sunstar on my legacy the pto and seat nanny are tied together. If the pto is not engaged and I get off the seat the motor shuts off. If the pto is not engaged and I engage the parking park the motor keeps running when I get off the seat. However if I engage the pto I cannot leave the seat no mater what. It does not matter if the parking brake is engaged or not; if the pto is engaged weight must be applied to the seat at all times or the motor shuts off. Maybe your Sunstar is wired this way. Rick......
My Prestige is the same way.

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BruceH
I had a problem with the PTO on my Sunstar not engaging. Through research on this site I was directed to the interlock module as being the possible culprit. The fix, until I replaced the interlock module, was to take the ground side of the PTO clutch directly to a bolt grounded on the frame. It worked fine however since the interlock was bypassed the tractor could be started with the PTO turned on.

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Brettw
Thanks all, this now makes sense. I figured it was some type of nanny that would require the ground wire to run back to a wiring harness and the inevitable hairball. I know one thing, the Sovereigns are an electronic cake-walk compared to all the stuff I see under this dash.

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MysTiK
Great info. dOd One little ditty w the electric clutch. They occasionally need a minor adjustment - to make sure they kill the engine in approx 3 seconds. Whenever I have had my Pacer mower /has electric clutch - into the shop at the Simp dealer, the mechanic always checks the clutch adjustment - and no charge for that! Which is nice. The mechanic says it's easy; and it's probably in the manual for the tractor as well. I'm not sure, never did it; but I think it's a "clearance" adjustment - and then test it live. Pretty simple. Only ever had to use it once - some kid and his dog suddenly appeared running at my mower. Nice option for potential damage control. Actually twice; when I ran over a steel cable - omg. :Q That was how I ended up in the Simp dealer's shop, for instant deck spindle repair, deck straightening, deck setup, and clutch adjust sm03 - worked real nice after that. It needed the tlc. I had no idea it had gone down that far. I want a Sunstar.

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Dark
like in a car the ground wire has a circuit of its own "nanny" or safety switches run off the ground side of the electrical system where as the power or lead side of the electrical is used for relays and direct power input devices. Some systems that we have retrofitted in the shop from manual to electric we wire the system so if the clutch is on the engine wont start and if the operator gets out of the seat the PTO clutch stops and a backup alarm sounds off,the operator after resitting would have to toggle the switch off then back on to reset the alarm and the PTO. We understand that you sometimes have to get off the mower and work with the engine still running but the PTO does not have to be. I would rather have a annoying beeper sounding off then have someone bypass the system having the need to unseat the mower to move or hook up something for tow. standard safety also applies to the mower being in gear and unseating. safety is always an issue but can be managed instead of bypassed.

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Brettw
quote:
like in a car the ground wire has a circuit of its own "nanny" or safety switches run off the ground side of the electrical system where as the power or lead side of the electrical is used for relays and direct power input devices.
Thank you, Mark. Great clear and concise information. News I can use, so to speak. I did not know that the safety modules and switches were based upon the grounding circuit. This will help in hunting any future gremlins as well. Outstanding.

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MysTiK
quote:
Originally posted by Brettw
quote:
like in a car the ground wire has a circuit of its own "nanny" or safety switches run off the ground side of the electrical system where as the power or lead side of the electrical is used for relays and direct power input devices.
Thank you, Mark. Great clear and concise information. News I can use, so to speak. I did not know that the safety modules and switches were based upon the grounding circuit. This will help in hunting any future gremlins as well. Outstanding.
Yup. Ditto. Agree. Welcome to the "Dark" side. I read everything this guy writes. dOd

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WITom
There is no tie-in with parking brake on the Sunstar. I have my seat nanny (funny, BTW - first time I've seen it called that!) bypassed. I can dismount the tractor with the deck running and no park brake and it all stays running. There is a neutral switch on the hydro lever that will prevent it from starting if hydro is not in neutral spot. All these interlocks are nothing but trouble, IMO. I have had issues with the interlock module on both of my Sunstars (it is located behind right side dash panel). I had to replace it on my Sunstar early on after buying it used. Cost a small fortune, but was an updated module. This was several years ago. Last week while mowing some tall grass, I had my deck just shut off for no reason. I had to flip the clutch switch off and back on again - worked the rest of the day without issue. Makes me wonder if that module is starting to give up the ghost again. If it dies again, I am rewiring the clutch to bypass the module once and for all.

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BLT
My son was complaining about intermittent to no engagement with mine. Then it dawned on me that the gap on the clutch was never checked almost ten years8. Looked up gap distance an told my son what to look for and adjust to. He called later and said the existing gap was large enough to drive a truck thru:D. He brought gap to within spec and the problems went away. Just a thought.;)

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comet66
Maybe Al will jump in here. It seems to me he mentioned (a few years ago) that there was a ground problem with some of the older units that caused them to go to ground through the engine bearings causing them to fail.

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