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OSCBRADLEY's avatar
OSCBRADLEY
Explorer
Mar 31, 2018

Onan genset removal question

Hello,
I have to remove my Onan genset it is a Cummins Onan RV QG 4000 Model 4KYFA26100P. I am taking it out of a 2016 Winnebago Minnie Winne 25B. Why you ask? well I ran it without oil in it last summer and found out the hard way there is no low oil cutoff. I decided in order to save some money I would take it out myself and bring it to a repair shop. It seems the removal is fairly straightforward but then i hit a snag. there are these 3 wires that run from the back of the moho to the genny and once they enter the genny I cannot find then, it seems they are underneath a circuit board that I tried to remove but could not. The wires are the only thing holding back the removal. Before I just them (splice them back together on install) I wanted to check with ya'll in case there was something i was missing here. Thanks!!!


  • I’ve seen the junction box a long ways from the genset, you could put another junction box closer if you like. When you find the junction box and pull the wires through pull a wire or string through the conduit for when you pull your genset wires back in.
  • Isn't there a small box mounted to the side of the genset compartment where the flex conduit ends?
  • OK, I took a look at the solenoid & Circuit board. I can see how the solenoid comes out but the circuit board......not so much
  • DrewE wrote:
    On my Onan of that model, albeit quite a few years older, the neutral and ground connect to a little star shaped thingy inside the generator opposite the 12V ground wire connection (that, indeed, the 12V ground wire is bolted up to). The hot wire snakes across the bottom and connects to the AC circuit breaker. To get to them, it was necessary to remove the starter solenoid and control circuit modules from the left side and to at least partly disassemble the control panel unit on the right side. A torx screwdriver of the appropriate size was about the only tool required, but it did take a bit of labor and poking around in slightly tight corners.


    I removed mine a few months ago, KY spec, and you still have to do exactly what DrewE said. Solenoid, board, and part of the switch unit.
  • Disconnect them at the junction box mounted to the interior of the genset compartment, not from the genset.
  • DrewE, I did exactly that. I followed the conduit that the 3 wires are in all the way to the back of the moho hoping there might be a disconnect someplace but wasn't able to find one.
  • These are the 3 wires that disappear inside the generator under a circuit board and I just cant get to them in order to disconnect them.


  • We can't see your images (they're sitting on your own computer, not online somewhere), but I think probably the wires you're talking about are the AC power output wires from the generator. There's a chance there's a junction box somewhere on the motorhome not too far from the generator where they could be unhooked.

    I'd avoid cutting them randomly; to splice them safely and legally, you'd need to have the splice enclosed in an electrical box (per the NEC), and if it's exposed to the elements or road spray it should be a weathertight box with appropriate weathertight wiring.

    On my Onan of that model, albeit quite a few years older, the neutral and ground connect to a little star shaped thingy inside the generator opposite the 12V ground wire connection (that, indeed, the 12V ground wire is bolted up to). The hot wire snakes across the bottom and connects to the AC circuit breaker. To get to them, it was necessary to remove the starter solenoid and control circuit modules from the left side and to at least partly disassemble the control panel unit on the right side. A torx screwdriver of the appropriate size was about the only tool required, but it did take a bit of labor and poking around in slightly tight corners.

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