Onan 5500 Fault Code 27 - Dutchmen Owners

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Old 04-07-2017, 10:48 PM   #1
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Onan 5500 Fault Code 27

This is all I've been able to deduce while searching the Internet. I have a fault code 27 on my Onan 5500 gas genie. We hadn't used the generator lately as we are almost always plugged into shore power. Last time we used it, it worked fine (February).

Today, it started and shut off within a few seconds and then the start button light started blinking steadily. Then I started it again and it ran fine but never switched the transfer switch to power the trailer. Same routine happens every time I start it now. Won't stay running in first start. Then runs steady on 2nd start but blinks at me.

I was able to grab the error code after hitting the stop button once (as recommended by someone on the Internet). I am seeing fault code 27. As near as I can tell, it suggests the generator is not producing current even though the engine is running strong.

Anyone else experience this and get it corrected??

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Old 04-08-2017, 11:58 AM   #2
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Two 30 amp circuit breakers right under the generator cover. Reset them. That will get the power back to the RV. Also, you need to run that generator under load for anywhere from a half hour to an hour, monthly.

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Old 04-09-2017, 01:34 PM   #3
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Yup. Tried that. Didn't make a difference. Seems like the transfer switch isn't see enough voltage to switch. Which probably isn't an issue with the transfer switch but more with the output of the genie.
Right now it's running in ERO (Engineer Run Only) mode. If I keep running it without the switch occurring, how can I put it under load?
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Old 05-13-2017, 12:40 AM   #4
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You can search and download ONAN service manual.


Logic: No Sense Voltage (0 VAC across S1S2) for 1 continuous second after start disconnect

Possible Causes: Genset loads, Inverter/Charger, VAC sense transformer, engine governor function, fuel supply, choke, demand regulator, carburetor, generator windings, ignition, wire connections, temperature

There is full page of individual steps that follows above. Based on your description of it sitting for extended period, recommend starting with fuel delivery system. Clogged filter, gumming of carb, bad gas, etc.
Doug & Tiffany
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Old 05-19-2017, 04:39 PM   #5
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I recently began getting Code 45 faults (Speed Sense Loss) and Code 13 faults (Undervoltage). The symptoms were just like yours; generator would start and immediately shut down, then run in Engine Only mode. The service manual suggested these faults could only be resolved by bringing into a certified Cummins Onan dealer, and that they would need to remove the entire generator out of the RV to inspect and service. I didn't have the means to do this myself, and dreaded bringing it in for service that would take weeks longer than it should and keep me from using the RV.

After several hours of research, I found a number of owners saying they learned (either through self troubleshooting or by way of a dealer) that the cause of their problems wasn't actually what the fault code represented, but rather a blown controller board, so I decided I would check that myself. Sure enough, like so many others my controller was toast. In searching for a replacement I found a company that makes aftermarket replacement controllers that claim to be of higher quality and also ignore the minor faults that cause the generator to shut down. The only faults it monitors that will cause the engine to shut down are low oil pressure and stator voltage - things that could either harm the engine or sensitive electronics powered in your RV.

After installing the new controller board earlier this week, my generator is working again as it should and powering everything in the camper. I have monitored the output voltage and frequency (Hz) using a digital Kill A Watt meter, and they're both where they need to be. If you are a do-it-yourself-er, it's quite easy to access the controller, just to see for yourself if this could be causing your issue. The way I figure, the $440 I spent on this new controller was definitely worth it compared to what I would have spent had I brought the RV back to the dealer for service (not to mention the time and hassle of getting it there).

Just so the admins know, I do not work for this company or represent them. I am just trying to help a fellow RVer.
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