Onan 7.5 QD (Quiet Diesel) Generator

[GStream40]

We have a Onan 7.5kw QD (Quiet Diesel) generator that has always ran perfectly until today.
We were traveling and it was running great and generating the electric current to run both our air conditions for appox. 45 minutes when all of a sudden it shut down. The light on the button was flashing 3 times in a cycle indicating that it needed service.
I checked the oil and coolant at the next stop and they were okay. I checked the circuit breaker on the generator and it was okay.
I started the genset up again and the engine runs fine, BUT it does not put out and 110 volt current.

I checked all the breakers in the coach and I cannot figure out what is wrong.

Any experts out there or maybe someone has had this problem that could give some clues at what to check??

It is no longer flashing any codes.

Thanks, Ron

[GStream40]

We have a Onan 7.5kw QD (Quiet Diesel) generator that has always ran perfectly until today.
We were traveling and it was running great and generating the electric current to run both our air conditions for appox. 45 minutes when all of a sudden it shut down. The light on the button was flashing 3 times in a cycle indicating that it needed service.
I checked the oil and coolant at the next stop and they were okay. I checked the circuit breaker on the generator and it was okay.
I started the genset up again and the engine runs fine, BUT it does not put out and 110 volt current.

I checked all the breakers in the coach and I cannot figure out what is wrong.

Any experts out there or maybe someone has had this problem that could give some clues at what to check??

It is no longer flashing any codes.

Thanks, Ron

[BOB E]

Make sure the air intake for the gen, engine, & radiator are clean & free of obstructions. All intakes are on the bottom of the unit. A blockage could cause overheating.
Next, with the unit off (& disconnected from shore power), start checking for loose connections, beginning with the 120/240 output terminals on the top, back corner of the gen box. Suggest tighten the terminals while you're in there. Follow the 110/240V output all the way to the breaker box,...should be a transfer switch in the line somewhere.
Make sure the transfer switch is functioning properly. Look for burn't contacts.
Also, you should be able to see the relay close when you start the gen.
With the gen running check for 120/240V output with a volt meter - begin with the output terminals on the unit.
If no voltage is present, the gen likely has an internal problem - take it to the dealer.
If you have voltage there, check voltage at the transfer switch.
You should be able to trace the problem to the fault by continuing down line to the breakers.

[RV Wizard]

Ron, when you are checking for power out of the generator you will not have any potential between L1 & L2. These generators are actually large inverters and the generator puts out 12 volts DC. You will have two 120 volt lines out and can measure each to the neutral lines for troobleshooting. If you get an error code again, push the stop side of the start/stop switch and you should get another set of codes; if 2 digits a pause will be in between the blinks of the light on hte switch.
If you have power coming out of the generator look at the transfer switch.
If not power out of generator you may have a bad circuit breaker on the generator; hopefully it is not the invertor. Good luck and let us know what you find.

[Gary RVRoamer]

My guess would be that it was overheating. Check for error codes as RV Wizard describes - the Onan will tell you the nature of the problem that caused the shutdown.

[GStream40]

Thanks for the replies and some guidance on what to check. Plan on getting into it tomorrow since it is supposed to cool down some temperature wise.

Will keep you updated on what I find or don't find and might come back with more questions.

I definitely will start at the genset checking for power.

Ron

[GStream40]

Well this afternoon I started checking things out.
Started with checking the genset wiring at the junction box that is mounted on the firewall behind the "hood" on the front of the coach.

To my surprise the genset was putting out 122 volts on both legs, well within range.

So I went to the transfer switch that is located under the cedar chest at the foot of the bed. I had 122 volts coming into the switch at the generator teminals, but nothing to the output side of the transfer switch.

The switch is a Iota Engineering Co. model ITS-50R Automatic Transfer Switch. Checked their website and downloaded the wiring and manual for this switch.

Read the information they had listed for the Time Delay Module that is built into the unit and how to flip the switch to test if this part is bad since the LED on the module was not lighting up as it should be. I flipped the switch and started the genset hoping that the Transfer switch would operate as was indicated in the instructions if the module was bad.

Nothing, zero, So the switch must have more serious problems.

I found a website for Solar Sellers and they sell the Iota ITS-50R Auto Transfer Switch for $115.00 plus shipping of $16.00.

So I will call them tomorrow to see if they have it in stock and can ship it right away.

Maybe I can have it by this weekend and get it installed. We are going to leave on the 21st for a week long Gulf Streamers Back Home Rally and we will need the roof airs while traveling, especially if the temperatures get up to 90 like it has been last weekend.

If after I receive the new one and am able to repair the old one, then I will keep it for a spare just in case it is needed.

Thanks to everyone for their guidance and input to my problem, it was much appreciated.

Ron

[RV Wizard]

Ron, it sounds like you have found the problem and are on the way to getting it fixed. Good luck and let us know if you need anything else.

[GStream40]

WOW, talk about great and fast service, I order the new transfer switch on Weds. and it was delivered in Friday's mail. Great service by the USPS Priority Mail and John Drake Services.

I installed the new transfer switch today and everthing works great, genset power was deliver through the transfer switch and I ran the both air conditioners for about an hour.

After I was all done, I took the old failed transfer switch apart, checked the coils, contracts, and wiring. All checked okay. Then I removed the Time Delay Circuit board and found a small burnt hole with black around it in the bottom of the circuit board. Hmmmm

Guess I found the failed part. I just ordered a new circuit board from Solar Sellers, John Drake Services for $16.00. I will install it and the test the transfer switch, if all is well then I will have a working spare just in case it is ever needed again.

All is well...

Ron

[BOB E]

Yup,...you really have to watch electrical components. An electrician buddy once told me that most electrical stuff runs on smoke. In other words, when you see smoke coming out they usually quit working,...so I guess this must be true.

[RV Wizard]

Ron, glad to hear you have got it fixed. Do you have a surge guard system on board?

[GStream40]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RV Wizard:
Ron, glad to hear you have got it fixed. Do you have a surge guard system on board? </div></BLOCKQUOTE>

Mike, We have the Progressive EMS portable unit that I installed in the cord compartment back in 2004 right after we purchased this coach. It saved us once from lightning when we were in Tenn. back in 2005. The Progressive EMS was replaced by Progressive because the lightning fried the unit but saved all the components in the coach.

Ron