marcob
I've found that there's a wealth of knowledge here in the forum. It's great that those with the experience are willing enough to pass it on to help others.  Thanks in advance to whoever reads this, I appreciate it.  I hope that this makes sense because I'm new to this.  

We've had this unit since Jan 2009 and it's held up pretty good as we've tried to maintain it's health with the necessary service.  We had a rpm sensor loss about a week ago and I've been using the diagnostic repair manual  G9266I to troubleshoot.

I have a question about the control panel/circuit board for this unit it has the led's.  Using a vom I can see the 12 VDC output from # 56 at J2-11 and incoming 12 VDC source voltage for circuit board on wire 13 at J1-3. 

There is no 12 VDC output from J2-3  wire #14 when the switch is in manual. Wire #14 has continuity from the J2 connector to the disconnected end where it plugs into the fuel solenoid.   What could be the possible cause for the no 12 VDC output from the control panel?

Thanks,
Marco
Quote
78buckshot
Hi marcob, welcome to the forum. I assume you have the control board compartment disassembled. Check the edge connector on the board for oxidized terminals. If you have some very thin probes for your VOM then after you remove and replace the connectors you can back-probe the wire terminals for voltage. Also check the fuses on the control panel, they have a history of poor connection within the fuse holder.
Quote
78buckshot
Since I can't figure out how to edit my post I'll give you a little more info here. The RPM sense loss most likely is from the starter not cranking so once you get voltage to the starter solenoid and fuel solenoid you will probably be back in business. The starter solenoid in a known item of failure on your model so if you get 12 volts to the terminals and intermittent cranking then a new solenoid is called for.
Quote
marcob
Hi 78buckshot, pleasure to meet you here on the forum.  I appreciate your welcome and thanks for your response with the information. I certainly do  appreciate it.  I will follow those instructions and will update with results.   78buckshot I had a after thought after I wrote this. One more question about hooking the board back up after I take a close look at it. Is it necessary to turn the transfer switch main breaker off, remove F1 fuse, and 7.5 amp before reconnecting N1/N2 connector !(240 VAC)?  Thanks again 78Buckshot for your time.  All the best to you and yours. 
Quote
78buckshot
To protect yourself and the equipment you should turn the generator to "OFF", turn the gas off at the generator, remove the fuses on the control panel, open the transfer switch and carefully pull the N1 and N2 fuses, disconnect one of the battery terminals, no need to turn the breaker/breakers off. The fuses in the transfer switch are 120 volts each and things are a little congested in there so be careful. When done in that order you should have zero voltage inside the generator except across the battery terminals.
Quote
Peddler
Power to the 14 wire does not occur until the controller senses that the unit is turning over so if that is not happening then no power to #14.  As has been stated the solenoid and starter can be weak links on this unit. 
Quote
marcob
Thanks 78buckshot and Peddler I will heed to both of your instructions. Again, I do appreciate your help.  You both have explained it well and made it crystal clear and now I have some clarity and understand how to move forward with this.  I'll be sure to update our results.  
Quote
marcob
We had a 55 degree day here in Ohio today, perfect for tinkering with this 55010 8kW.  What I found so far is that the generac is getting 12 VDC from the battery to the starter contactor stud where the battery cable connects.  The starter contactor stud that has the cable that goes to the starter motor is only getting about 8 VDC when I attempt to start it in manual.  Shouldn't that stud transfer the 12VDC to the starter motor? The J2-11 harness end and Wire 56 has continuity from it's disconnected end at the SC and choke solenoid.  I can even see the choke closing as I press the manual start switch.  The starter contactor smaller terminals measure about 4 ohms.  
Quote
JayH
marcob wrote:
The starter contactor stud that has the cable that goes to the starter motor is only getting about 8 VDC when I attempt to start it in manual.  Shouldn't that stud transfer the 12VDC to the starter motor? 


It should, and it sounds like it is. The starter motor is a heavy load for the battery. When it engages the battery voltage drops. There is an additional drop in the wire from the battery to the solenoid and from the solenoid to the starter motor.

How old is the battery? During cranking, what is the voltage across the battery terminals? If the voltage during cranking at the battery itself is only around 8 or 9 volts, it's probably time for a new battery. With a good battery you should have 10 volts or more while cranking. Also if it's a flooded (liquid electrolyte) battery, very carefully, with the controller in OFF position, look at the electrolyte level inside. Wear safety glasses. If the liquid is below the plates, very carefully add distilled water to the fill line. Liquid level below the plates is a very hazardous condition as it allows sparks to ignite which can cause the battery to violently explode.

If the battery is more than three or four years old it's probably due for replacement.
Quote
marcob
Thanks JayH for the response.  The battery was purchased on 7-6-18.  I'll check the volts across the battery terminals tomorrow and will heed to the safety instructions. Thanks for your help.
Quote
78buckshot
If you are sure that the battery has a full charge and only 8 volts to the starter then I suspect the starter solenoid is bad, as noted in the post by JayH you should see 10.5 - 11.5 volts dc while it is cranking. I have replaced many of them but I don't use the Generac solenoid due to poor quality. I add a Generac starter contactor relay to energize a new aftermarket starter solenoid. This basically duplicates the set-up used on the twin cylinder models.
Quote
marcob
Thanks 78buckshot I'll check the dc volts while it's cranking to see what it measures.  I did replace the starter contactor with the 086726. Again I'll check the battery out to make sure that's not the source and will update.  Thank you.
Quote
marcob
  (Update)  At about 30 degrees, the battery from post to post was 12.85 before cranking. After a few manual cranking attempts it then read 12.42, 12.36 and 12.23 at each cranking attempt and from the contactor stud to the starter motor measured 9 VDC.  This is a flooded battery and the electrolyte level was down a bit, but not to the degree that the plates were exposed. I did add a little distilled water to each cell.  After adding the distilled water the battery was at 12.73 and I watched it for a few minutes as it rose to 13.28 before attempting to start.  After a starting attempt the battery was at 12.47 from post to post and slowly rising but cranking from the contactor stud to the starter motor was 7.9, 8.0, 8.6, and 8.7. on each attempt. 
Quote
Geoff Z
Are you reading across the battery terminals while the starter is actually engaged? It sounds from what you have written you are taking before and after readings? Our techs are asking for a voltage reading during crank cycle. While the battery is actually under load from the starter. 
Quote
marcob
Hi Geoff Z thanks for your response. Sorry if I confused you. Yes, the post to post reading of the battery during these three starting attempts was the 12.42, 12.36 and the 12.23.   

The starter motor only engages for about 1-3 seconds during these attempts to start in manual mode and then it seems to go into a rest.  That's what it's been doing from the start when we first noticed the rpm sensor led on. It will not crank cyclically so I have to switch to off and then back to manual to try to start it each time in order to get a quick reading from the vom.  
Quote
Geoff Z
Thanks for the clarification. You have clearly determined the battery is good. I’m sure our techs will join back in when they are able. 
Quote
marcob
Thanks Geoff Z, I appreciate your help.  Everybody's been very helpful. This is definitely a great site to have access to. 
Quote
78buckshot
From the info you have given it leads me to think the controller is at fault, did you find any oxidized or otherwise imperfect connectors, fuse holders, suspicious wiring? Lets see if you can 'hot wire' it and get it going. If you have a jumper wire with alligator clips attach one clip to the small post on the starter solenoid that gets 12 volts from the board, the other end will be used at the hot battery post on the solenoid after you have turned the manual run switch on. So you say that the starter will crank a short time and stop, after it stops then you can energize it again but this time your bypassing the board and switch, leave the switch in manual and touch the jumper wire to the hot battery post on the solenoid. It might scare you a little as it begins to crank but it should not stop cranking until you remove the jumper. If all else is working correctly then you should be able to crank it until it starts at which time you can disconnect the jumper.
Quote
marcob
I didn't notice any oxidized connectors, imperfect connectors, suspect wiring or fuse holder. I will get out my head magnifier so that I can take a closer look at all of those and will follow through with your instructions. Thanks for your help 78buckshot.
Quote
JayH
You have high resistance somewhere between the battery and the starter. It could be that a battery cable is loose, a battery cable is bad, the starter contactor is bad. Measure the voltage at the contactor on the post connected to the battery and then on the one connected to the starter. If the drop is in the contactor, replace it. Also check the battery negative cable, its clamp, and its ground connection.
Quote
marcob
Thanks JayH,  I will follow those instructions and I appreciate you taking time to respond.
Quote
marcob
Update:  I just wanted to give a big thanks to 78buckshot, Peddler, JayH, and Geoff Z for your help in guiding me through a thorough diagnosis of our 8kW. Each one of you caused me to take an action that led me to narrow down the issues that were preventing our Generac from starting. The original starter contactor and starter motor both needed to be replaced.  It now starts with the switch in manual and it exercises with the switch in auto.  It was an interesting project and I learned so much from you guys in a short period of time. I learned more from you all in a week or so than I would have in the next twenty years had these issues not have came up.   Thanks again and I appreciate you all.
Quote
78buckshot
How did we survive before these new-fangled toys, forums are great. Thank you marcob for the update.
Quote