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rpasetto · 06-08-2023, 07:26 PM

Started up the genset, Onan 4000, as usual. No 120v to refer, microwave or outlets in coach. I looked over the Winnebago diagram (screen-shot below) which show a junction box (red Arrow) to rear of genset with a connection from genset cable to one running to the the Transfer switch (green arrow) at rear. I checked the wiring in the Junction box with a VOM and got zero volts.

I can think of two possibilities: either the circuit breaker in genset has gone bad or there's something wrong with genset's control board. Not sure how I can check whether problem is with one or the other of these.... or something else.

Before I start pulling things apart... Suggestions? Comments?

rk911 · 06-08-2023, 07:43 PM

simple things first. reset the breakers ON the genny and report back.

BirchyBoy · 06-08-2023, 08:25 PM

Quote:

Originally Posted by rk911

simple things first. reset the breakers ON the genny and report back.

Ditto this. It took me several times of trying different settings to no avail. I called Winnebago and they said to check the breakers. Boom! Power!

SuperGewl · 06-08-2023, 08:36 PM

Oh yeah, to properly Reset the Breakers. Shut them both OFF and then switch them both back on. Some of the switches don't actually move to the OFF position when they are tripped.
Let us know what the results are.

twinboat · 06-08-2023, 11:40 PM

Most generators won't run if they are not making power.

Yours runs, so start at the breaker and work towards the RV wiring.

rpasetto · 06-09-2023, 04:51 AM

I should have been clearer. First thing I tried was resetting the breaker on genset. Tried several times. That's why I suspect the breaker might have gone bad. Also reset inside house breakers.

Dale & Mark Bruss · 06-09-2023, 04:55 AM

The transfer switch is not working.

rpasetto · 06-09-2023, 05:22 AM

Quote:

Originally Posted by Dale & Mark Bruss

The transfer switch is not working.

Maybe I am misinterpreting the diagram from Winnebago. It sure seems like the genset cable goes to the junction box behind it and then to the transfer switch. Could it be the other way around?

rpasetto · 06-09-2023, 05:28 AM

Quote:

Originally Posted by twinboat

Most generators won't run if they are not making power.

Yours runs, so start at the breaker and work towards the RV wiring.

I did measure voltage at the junction box behind the genset. I'm not sure how to disassemble the box on the Onan 4000 genset which contains the start switch and breaker Was hoping that someone here has taken that apart before. I guess my next step will be pulling it apart by trial and error, connecting start switch and circuit breaker via jumper leads, and measuring voltage at leads after starting the genset.

SuperGewl · 06-13-2023, 05:50 PM

So what you are saying is that when running on the generator you have No AC power at all in MH or you have partial AC power in the MH? When hooked up to shore power does everything work? Not sure about the drawing, but most generators run directly to the Transfer Switch or in some cases to a receptacle that you plug the shore power cable to and you would not have a Transfer Switch.

rpasetto · 06-14-2023, 03:31 AM

Quote:

Originally Posted by SuperGewl

So what you are saying is that when running on the generator you have No AC power at all in MH or you have partial AC power in the MH? When hooked up to shore power does everything work? Not sure about the drawing, but most generators run directly to the Transfer Switch or in some cases to a receptacle that you plug the shore power cable to and you would not have a Transfer Switch.

As drawing shows the cable from the genset runs to a junction box behind it. No power at that junction box with genset running. Seems to me something in the genset has gone out so I am planning to swap out the circuit breaker in the genset.

Isaac-1 · 06-14-2023, 05:48 AM

You need to measure the voltage at the terminals at the transfer switch, and work towards the generator from there.

rpasetto · 06-14-2023, 07:22 AM

Quote:

Originally Posted by Isaac-1

You need to measure the voltage at the terminals at the transfer switch, and work towards the generator from there.

Why would I need to measure voltage at transfer switch? Voltage at the junction box measures Zero and it is wired between generator and transfer switch. (see diagram above) Even when I disconnect cable in junction box going to xfer switch, the voltage at cable coming from the generator is zero; generator running of course.

I know the voltage coming from the generator is zero; my question regards how to find out what, in generator is wrong.

Ray,IN · 06-14-2023, 09:59 PM

When the genset is running, is the switch light on solid/continually or is it blinking?? Step 3 of this paper explains how to replace the breaker.

This paper explains what each component of the genset does and why. Also there is the possibility the generator has lost its magnetism, to correct that use this guide.