RV Onan Generator Starts but No Power [How to Fix]


When we’re in our home away from home, we trust that our RV will provide us with the power that we need for the essentials of modern life. You know, coffee, air conditioning and using a blow dryer. But what should you do when you go to use the Onan generator and nothing powers on?

Luckily, there are 3 simple solutions that you can check prior to getting a mechanic or electrician involved.

Generally, an RV generator engine will run but not produce power if the breakers inside of the RV panel are tripped, a GFCI receptacle is tripped, the power cord of the generator is loose or corroded, or the circuit breaker switch on the generator itself is tripped.

ProblemSymptomHow to Fix
Breakers in RV Panel Are TrippedNo power to the circuit breakers that are affectedTurn the breaker switch “off” and then “on” again even if it appears to be already in the “on” position
GFCI Receptacle TrippedNo power to the GFCI receptacle and to any number of receptacles that are tied to it electrically inside the RVPress the “reset” button on all of the GFCI receptacle
Generator’s Power Cord is CompromisedNo power to anything, flickering powerTurn generator off, ensure the cord us properly plugged in and not corroded
Generator’s Circuit Breaker is TrippedNo power to anythingLocate the circuit breaker on the generator (generally near the bottom by the start switch) and turn it “off” and then “on”

Breakers in the RV Panel are Tripped

Since you’re already likely inside the generator, you can start with checking the breaker panel inside first.

Don’t be deceived by breakers that look like they’re in the “on” position. If you don’t have power, go ahead and turn them to the “off” position, one by one, until you’ve got them all properly reset.

When a breaker trips, it will visually stay 7/8 of the way in the “on” position, so don’t be tricked.

Image showing the circuit breakers inside an RV that might be tripped
Circuit breakers located under the bed in my RV. Yours may be in a different location. Push them down to the off position, one at a time, and then turn them back on to make sure they aren’t tripped.

GFCI Outlet is Tripped

Before you head outside, make sure to also check to make sure your GFCI (Ground Fault Circuit Interrupt) receptacles inside the RV are not tripped as well.

In this case, you will likely have partial power in your RV but you might have a string of receptacles that are not energized.

RV wiring is not done like it is inside of a house, and in many cases you may have a GFCI receptacle that is upstream of 3-5 normal receptacles downstream of it. If the GFCI trips, then everything downstream will stop working.

Typically, these receptacles are located in the bathroom or the kitchen area, so be sure to hit the “reset” button on them before we head outside.

Generator’s Power Cord is Compromised

If the two indoor solutions didn’t work, go ahead and turn off your generator.

Now, find where your power cord for the generator plugs into the RV and ensure that it is not loose, disconnected, or corroded.

image of a 30A 125V RV power cord

If you see corrosion on the pins, you can try to wipe it with a rag and buff it lightly with fine grit sandpaper to expose clean copper and then wipe it again with a rag to get any of the metal dust off of it.

Always be sure to have your power cords firmly attached and in place before you start up the generator or plug your RV into the campground pedestal. You will wear out your pins on your plugs prematurely by trying to plug them in after power is already flowing due to the arcing that occurs as you bring the cord to the pedestal and RV to plug it in.

Generator’s Circuit Breaker is Tripped

The first time I ran across this issue it had me scratching my head for a little but until I had the “ah ha” moment and realized I had forgotten something so simple but easy to overlook.

image showing where an accidentally tripped circuit breaker is located on an Onan RV generator.
The circuit breaker switch on my Onan RV generator.

On the Onan generator itself, near the bottom and usually around the start switch, there’s a small breaker switch that can easily get bumped if you’re doing any regular maintenance — especially if it has a missing cover.

Go ahead and switch this to the off and on position and you’ll likely find that your power will work perfectly.

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Robert Van Nuck

Robert lives in central Michigan and enjoys running, woodworking, and fixing up small engines.

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