David Pratt Posted August 18, 2023 Share Posted August 18, 2023 The Control Unit is located in the front of the generator. You have to unbolt and move the Coolant Expansion Tank and the Air Filter Assembly for access. It is mounted behind/forward of those components Google "Replacing Onan 10/12.5K Control Board Location" and "Replacing Onan 10/12.5K Control Board". Lot of good Tutorials on how to do it Link to comment Share on other sites More sharing options...
philcarrell Posted August 18, 2023 Author Share Posted August 18, 2023 25 minutes ago, David Pratt said: The Control Unit is located in the front of the generator. You have to unbolt and move the Coolant Expansion Tank and the Air Filter Assembly for access. It is mounted behind/forward of those components Google "Replacing Onan 10/12.5K Control Board Location" and "Replacing Onan 10/12.5K Control Board". Lot of good Tutorials on how to do it Thanks Link to comment Share on other sites More sharing options...
96 EVO Posted August 19, 2023 Share Posted August 19, 2023 Hey, if you can access it through the service door, that's the way to go! Removing any of the top cover is a PIA! Link to comment Share on other sites More sharing options...
philcarrell Posted August 19, 2023 Author Share Posted August 19, 2023 I got it out. Removed side access door, then removed the overflow tank and it was right under that. The numbers on mine do not match the # Dave Pratt gave me. I will call Flight Systems Monday and give the the #'s I found. Thanks for everyone's assistance. 1 Link to comment Share on other sites More sharing options...
David Pratt Posted August 19, 2023 Share Posted August 19, 2023 The Onan part number for the Control Board is 300-5961. That is the part number from the ONAN Generator Parts Manual. The part numbers on the Control Board are not the part numbers. The Flight Systems replacement part number is 56-5961-00 for their rebuilt unit. Both the 10K/12.5KHDK generators use the same control Board/Unit. But you should check with Flight System to verify. The following pictures show the hot/burn spot on the Control Board that I discussed earlier. Picture 1 shows the two areas of concern and show evidence of the boards getting hot. Picture 2 is a close up of the upper left corner in Picture 1. Picture 3 is a closer look of Picture 1 that is rotated upside down. Picture 4 is picture 1 rotated upside down. 1 1 Link to comment Share on other sites More sharing options...
Ivan K Posted August 19, 2023 Share Posted August 19, 2023 My older 12.5k uses a different 2 connector board in a different location and has been good for over 4k hours sofar. At some point they made rev. C that may not have gone too well. I also have a couple of fuses protecting starter and battery feeds that were later eliminated. Link to comment Share on other sites More sharing options...
philcarrell Posted August 20, 2023 Author Share Posted August 20, 2023 Mine is exactly like yours Dave. I emailed Flight Systems today and gave them the symptoms. I'm sure I will be getting your recommendation. Mine shows no burnt spots but may have a short. 1 Link to comment Share on other sites More sharing options...
philcarrell Posted August 31, 2023 Author Share Posted August 31, 2023 Got the new controller from Flight systems and installed. Hit the start button and heard the fuel pump come on and no sign of the starter turning over. Checked batteries and all were up. Started the MH and still nothing on either start switches for generator. Where do I go next. Link to comment Share on other sites More sharing options...
Tom Cherry Posted August 31, 2023 Share Posted August 31, 2023 1 hour ago, philcarrell said: Got the new controller from Flight systems and installed. Hit the start button and heard the fuel pump come on and no sign of the starter turning over. Checked batteries and all were up. Started the MH and still nothing on either start switches for generator. Where do I go next. First…never trust the cables. Take your vehicle and use jumper cables to the studs on the back of the Genny. Then start it. Mine (8Kw….but this would be the same for a 10] would not turn over. Turns out the House batteries were perfect. The issue was a corroded negative ground stud connection behind the box. I cleaned both House and Chassis Ground studs and cable ends…never a problem in the last 8 years. word of caution. If there is a dirty connection on the genny studs, the bolts are brass. Apply too much tightening torque and you get to totall Disassemble the cabinet to replace. Not me, but a very astute member. If it cranks from jumpers…trace negative and clean ground…then go back on positive…. Fuel pump says 12 VDC Voltage works….but no high current (amps) power. Otherwise, bad starter or bad starter solenoid…if it has one… Link to comment Share on other sites More sharing options...
David Pratt Posted August 31, 2023 Share Posted August 31, 2023 If the generator was Cranking/starting and running before you replaced the Controller and all you did was replace the controller it should start and run. Make sure the controller is plugged in correctly. If all you did was replace the controller and it won't start after it goes through the automatic pre-heat timer sequence and the fuel pump is running it should automatically crank and start. If not, my next call would be to Flight Systems. Ya never know, new parts can be bad out of the box. It would be unusual for this company, but crap happens. 1 Link to comment Share on other sites More sharing options...
philcarrell Posted August 31, 2023 Author Share Posted August 31, 2023 1 hour ago, David Pratt said: If the generator was Cranking/starting and running before you replaced the Controller and all you did was replace the controller it should start and run. Make sure the controller is plugged in correctly. If all you did was replace the controller and it won't start after it goes through the automatic pre-heat timer sequence and the fuel pump is running it should automatically crank and start. If not, my next call would be to Flight Systems. Ya never know, new parts can be bad out of the box. It would be unusual for this company, but crap happens. I plugged it in just like the other one came out. Put the old one back in and same thing NADA will try what Tom Cherry said. Thanks to both of you. Link to comment Share on other sites More sharing options...
Dr4Film Posted August 31, 2023 Share Posted August 31, 2023 (edited) Sounds to me like something else coincidentally happened that needs to be resolved. Time for troubleshooting steps to begin. Edited August 31, 2023 by Dr4Film Link to comment Share on other sites More sharing options...
philcarrell Posted September 2, 2023 Author Share Posted September 2, 2023 (edited) SUCCESS!!! After checking voltage into genset at 12,8V, I called Flight Systems yesterday AM. I talked to Tom and relayed all that I had done. He asked me how hard did I press the connector into the controller told him it went in pretty easy. He said you basically have to stand on it. I got back into genset and pushed and pushed and finally got it seated. Viola it started up. I turned on AC's moved it outside and it ran over 3 hours. There is very little room in the controller area so you can't get but one hand in there to push. So it appears that a 77 year old does not have the hand strength he used to have. Thanks again for all of the suggestions. Edited September 2, 2023 by philcarrell spelling 3 Link to comment Share on other sites More sharing options...
David Pratt Posted September 2, 2023 Share Posted September 2, 2023 On 8/31/2023 at 11:38 AM, David Pratt said: If the generator was Cranking/starting and running before you replaced the Controller and all you did was replace the controller it should start and run. Make sure the controller is plugged in correctly. If all you did was replace the controller and it won't start after it goes through the automatic pre-heat timer sequence and the fuel pump is running it should automatically crank and start. If not, my next call would be to Flight Systems. Ya never know, new parts can be bad out of the box. It would be unusual for this company, but crap happens. 2 hours ago, philcarrell said: SUCCESS!!! After checking voltage into genset at 12,8V, I called Flight Systems yesterday AM. I talked to Tom and relayed all that I had done. He asked me how hard did I press the connector into the controller told him it went in pretty easy. He said you basically have to stand on it. I got back into genset and pushed and pushed and finally got it seated. Viola it started up. I turned on AC's moved it outside and it ran over 3 hours. There is very little room in the controller area so you can't get but one hand in there to push. So it appears that a 77 year old does not have the hand strength he used to have. Thanks again for all of the suggestions. Damn, Congratulation on your success, I love it when things come together correctly! 1 Link to comment Share on other sites More sharing options...
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