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Onan 10HDKCA fault 27

96 EVO

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Tried to start the gen today for it's monthly exercise. Fires, then immediately shuts down. Throwing fault 27 Voltage Sense Loss.
The breaker doesn't trip. I disconnected the three plugs I could get at without removing the entire top panels, sprayed them with contact cleaner, and made sure they snapped in properly. No luck.
Tried starting it from the switch below the Intelletec load meter, with shore power still connected (small load). The strange thing about this was the gen still wouldn't start, throwing the same 27 fault, but the panel would alternate back and forth between gen and 30A service constantly, until I cleared the gen fault code, then it would stay on 30A, and the load shedding lights would start illuminating.

Transfer switch looks fine, with all lugs tight, although I'm pretty sure this ATS has a built in delay for the gen speed to stabilize.

Any ideas?

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When you start your generator and it fires off it is looking for two things to stay running. The first thing is the AC voltage. It cannot be any lower than 95 VAC and no higher than 132VAC. It also looks for the 60hz frequency. If the generator does not see either one it will not run.

Code 27 suggest that the generator is not seeing the correct AC voltage. Possibly either the ECU has gone bad or the Stator or a winding in the coils may have failed.

My suggesting is contact Cummins for more help

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Thanks David.

In the next few days I should have time to remove the top covers and start their testing procedure. The entire top has to be removed due to the front piece of top cover, tucked under the rear piece.

Hopefully, worst case, it only needs a ECU. 

Gen has less than 300 hrs ☹️!

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I hate to be discouraging but I had a similar problem with a QD 7.5 and, as I remember it, the same code. The ECU was not seeing the correct voltage or frequency and shutting the engine down. A service center removed all the covers and found that a magnet had become "unbonded" and had damaged the stator, rotor, and the cooling fan fins. Chunks of the magnet were throughout the interior of the generator case. They replaced the rotor, stator, and cooling fan, which only took a day after getting the parts from Cummins. Fortunately, the electronics were not damaged but the repair was still $3,000. Before authorizing the repair, I spoke to the closest Cummins center and they said that they would replace the entire generator, not rebuild it, adding several thousand dollars more to the cost. The generator had less than 500 hours on it when the failure occurred. That was 5 years ago and it continues to perform well. 

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Well, that went SO much easier than expected!

Pulled the top panels off. When I went looking for the first 4 wires needed to start the testing procedure, found one of the connectors had come apart. Connected them back up and she's purring away.

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Well, the fix for the gen was easy enough, and 0$, but it looks like I damaged the transfer switch.

Even though the gen wasn't running, the EMS switching between shore power and gen power while the fault code was displaying on the start stop switches apparently took out the transfer switch delay board. Shipping of the replacement board  to Canada, is more than the board itself!

No more starting the gen while shore power is still connected for me!!

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