hobblehill
Hi Guys .    We have a 5 year old Generac Gaurdian that ran great last few years.    Our problem started last year , kept getting a crank and total no start .  Low Voltage Error .      Did replace the circuit board last summer did run ok a few times .          But now will only run great on manual .    But now no auto start when power fails.    Did a few shut off power tests.   nothing .   only now Low Voltage Error.        I thought I had heard there was a re-set for the circuit board to get it back to working ??    Or do I need to adjust something ??  
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Geoff Z
Welcome! Please read the How to receive help from this forum post and give us as much information as you can. Our techs will offer help when they can but need more to go on. Thanks
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hobblehill
Hi , here is the more info that was asked for  ,  Thanks    Model # 0058721       Serial #  6519393  tot run hrs 88
Lp propane inch piping about 18 feet away.           Last maint was 2 years 5/2017    

The status of the red , yellow and green lights on the side are :     switch to AUTO light is Green .   
Switch to OFF  light is Red      When switched to Manual  cranks and runs fine. 
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hobblehill
Last valve adjustment date: n/a
Last battery replacement date: original battery , has plenty of charge
changed oil and filter last summer.
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Peddler
You should ohm out the low voltage wires (#23 & #194) to make sure there is not voltage bleeding over to them from the high voltage control wires or to ground.  I have seen the wiring error fault sometimes after a lightening storm where a nearby strike induced a voltage on these wires otherwise it is coming from N-1, N-2 or T-1 
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Peddler
You can try to reboot the controller by de-powering it and then bring it back though this is often ineffective.
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Geoff Z
We/I stole this discussion away from hobblehill when we went in the battery direction. We will leave this thread for him. If you would like to continue on with the battery discussion you can find it here:

https://www.zillerstore.com/post/discussion-about-battery-life-and-generator-dependability-9996544?pid=1307084198
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hobblehill
changed the exercise times to the next days to make sure I was there.  Each day no start just 'Under Voltage" error.
But again when I flip the  main power off and the generator senses a power fail it will crank and start and shut-off ok 
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Geoff Z
A question for our techs: Is this a unit that does whisper test? If so could he benefit by trying to set exercise to full speed, run another exercise test and see what happens?
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Peddler
Is the unit actually starting on exercise and then faulting out on undervoltage?  Is the problem of undervoltage only when it exercises?  Is the unit set to exercise at low speed, "quite test"?  If so you may need to clean the brushes and slip ring so it will make more voltage at low speed or it could be the controller not correctly interpreting the lower voltage of the low speed test.
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