Onan quiet diesel 7.5 trouble code 15

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Captain154

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Dec 16, 2017
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Need help please. I have a 1999 Monaco diplomat with a onan 7.5 quiet diesel. The generator will start up but dies after just a few seconds. Shows a code 15.  Has anyone ever had this problem before? Thanks in advance.
 
You may already know what the code means, but just to make sure I'll tell you what the troubleshooting manual says:

INVERTER UNDERFREQUENCY FAULT - CODE NO 15

CORRECTIVE ACTION:
1.  Reduce the number of connected appliances, especially when A/C and battery chargers are running.
2.  Have A/C and other appliances checked for proper operation. (A locked compressor rotor can cause very low power factor.)

Beyond that, I cannot help.  Just had my code 36 repaired by Cummins.  A filter I didn't know existed and located on the 'rail' was clogged.

 
After I posted above, I realized that there could be more than one code.  Did you check for that?
 
Thanks, that is the only code showing, I have tried with everything off and with the main breaker off at the generator itself, but had same results
 
The Onan advice only addresses external causes, but there are internal possibilities as well.  The inverter in the Onan 7500 relies on DC power produced by the diesel engine plus DC generator, and inadequate power there can cause the inverter to malfunction, making power that is not the 60 Hz frequency it should be. May also be under voltage if that happens.  A faulty inverter module is another possibility (expensve!).  I'm pretty sure there is nothing you can do to fix this, so professional help will be needed.
 
I made the classic mistake, about nine years ago , of shutting off the generator without shedding the heavy loads first.  A $1400.00 mistake I haven't made since.. Had to have the inverter replaced at a local Cummins shop.>>>Dan
 
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