Onan 5500 generator, stops after a few seconds, shows code 41

[JeffAndPam]

I have an Onan 5500 in a 2005 Fleetwood Flair (specs are in the image at the bottom).

When I try to start it, it starts up for a few seconds, then stops, and displays a code 41, which from the manual indicates:
"GENERATOR ROTATOR FAULT - Controller unable to sense field or output voltage"

BACKGROUND:
I last started it in January when outside temp was 17F. Was sluggish, but started. I hadn't run it since then. We've only used the RV once since then (one overnight, on shore power).
I just tried starting the generator over the weekend. The first few times I started it wouldn't start. I forgot that I had left the shore power plugged in. I unplugged the shore power and tried starting, but still get the same problem, and the code 41 above.

So two potential influences: 1) Not running it for a few months. 2) Trying to start it a few times while on shore power.

Any suggested things to try (other than testing the fuel pump, which was working)?

SPECS:

 

[Kevin D Pem]

Code 41 is your key!

Due to field strength manipulation (regulation for a better output). Your generator has a commutator and brushes for the field (rotor). This could be a bad connection, bad brush contact, or a control board.

No matter, your generator has a shut down for this fault is my guess. You are going to need to trace the circuit to find that open.

A side note:

Not only have I been offered some of these Onan generators at no cost, but I have been unable to find anyone willing to take such when running! Messing with them in my environment, is simply not worth my time.

They are quality, old technology, that most feel are to expensive to keep running, for full time use.

The consensus is the modern inverter generators, not only have a cleaner output, but are also less expensive (fuel wise), to use when needed.

Good luck with your trouble shooting!!!

 

[JeffAndPam]

This could be a bad connection, bad brush contact, or a control board.

Thank you Kevin.
I'm learning (the hard way) I should start with simplest solutions first.
Given that, what do you think I should focus on first (and how)?

 

[NWIP]

Generator Rotor Fault -Code 41 (Contoller unable to sense field or output voltage).

I would look at the brushes as Kevin suggested

 

[JeffAndPam]

UPDATE:
I just tried again, and this time see another code: 45.

So these are the two codes that have appeared:
41 - "GENERATOR ROTATOR FAULT - Controller unable to sense field or output voltage"
45 - "SPEED SENSE FAULT - Controller unable to sense quadrature frequency"

Given that, should I focus on the Controller? I see a few on ebay, perhaps purchase one that can be returned?
Or is there something simpler to start with?

 

[Chuggs]

I had an issue with ours…something about speed. I thought a new control board was in my future. Cummins couldn’t trace the problem with their laptop…decided to go inside. A loose screw. A screw in the intake would get sucked into the speed Governor and scramble the signal…so the unit shut down each time we started it.

Guess we got one manufactured on Friday….

Works now…hope they used locktite.

 

[Kevin D Pem]

Chuggs makes a very good point! A simple loose wire or corrosion,can cause many electrical problems.

That said,the first thing you should check are electrical connections.

Your codes indicate there is no 115 being produced. That still leads me to no field! Check all connections leading to the brushes. Make sure water has not corroded them! Literally, if your field has no power, you will not get any output. No output the control will not be able to read the frequency!(that would be the second code 45)

Mind you, I am no expert on Onan generators. If you're model has a self exited field, you will find a run capacitor that energizes an Exciter coil. I don't expect you will find such an item, but if there are no brushes,you will. And that capacitor if bad would likely be the culprit.

 

[JeffAndPam]

That said,the first thing you should check are electrical connections.

Sound like a good start! TY

So I'm curious, can I do all this without removing the generator? I watched this video:


From that, I see the brushes are on the back side. He cut a hole in the side of his generator and inserted an access panel. I don't have room to the left of the generator like he does.

Also, i tried to find the control board, but am not sure where that is. I pulled the box where the starter switch is located and looked behind that, It wasn't there. I found this link:
Onan 5500 Generator Parts Breakdown
but couldn't see where the control panel is.
UPDATE: See next post.

 

[JeffAndPam]

UPDATE:
I've found two good videos to help with this:


and:


So now I have the info I need to get started...

 

[Kevin D Pem]

The 95 bego I had had a tray I could slide out. I simply supported it when I slid it out. That was much easier than trying to get in places in didn't fit!