This article applies to Roadtreks with the Onan gasoline powered generator Microlite 2800 models up to the KY model that came out mid to late 2012. It applies to the KV model that is the model before the KY and should apply to earlier Onan's. I DO NOT KNOW if it applies to the newest Onan Microlite 2800 model as that has a very different motor.
The Onan Microlite 2800 gasoline generator in the Roadtrek will at times not start - it does not try to start and stop. When the start switch is pressed - either on the wall or inside the generator itself - the motor seems to be DEAD! This could be a mechanical issue inside the Onan but the first thing to check is the FUSE inside the Onan. Early Roadtreks had the Onan in a compartment on the outside of the van on the side wall. These are easy to work with inside the generator. Later Roadtrek moved the generator under the chassis of the van. Look under the rear bumper toward the driver's side and you will see it hanging down. The FUSE is inside the generator case. The fuse is between the Roadtrek battery(ies) and the ignition of the generator motor and this goes through the generator's control panel.
Sometimes the generator starts just fine - and runs perfectly but there is no 120 volts of AC power coming out of the generator. You turn on the A/C and nothing happens! You turn on the microwave and nothing happens! The first thing to check is the CIRCUIT BREAKER inside the Onan! The internal Onan CIRCUIT BREAKER is between the Onan's output and the Roadtrek!
As you can see in the illustration above - the breaker and the fuse are near each other.
Getting to the Onan when it is under the chassis -
I should not have to say this but before going to the generator SHUT THE GENERATOR OFF!
Sorry to say, you have to crawl under the back of the van's rear bumper on the driver's side either on your back or on your belly. When you get close enough it will be above your head - and it is a pain to work on it propping yourself up on your elbows or reaching up on your back looking at it upside down.
You then have to remove the access panel on the front of the Onan's case by pushing up on the two buttons - shown in the first illustration - at the same time and then pull forward and down on the panel to take it off. Once the panel is off you will see an open space in the middle - as shown in the second illustration. In the picture here it is easy to see. Looking inside the Onan upside down or trying to look up at it - it is not so easy to see. You might not see it all all. if that is the case you are going to have to rely on touch.
FOR THE FUSE - PUT TWO FINGERS IN AND FEEL FOR IT - it is a regular automotive blade type fuse - 5 amps. Get hold of it with two fingers and pull it out (try not to drop it). Look into the center of the top of the fuse and see if the metal connection inside is broken. If so the fuse is blown and must be replaced - and when you do so the generator will start right up - if this was what the problem is.
FOR THE CIRCUIT BREAKER - PUT A FINGER DOWN AND FEEL FOR THE LITTLE BLACK HANDLE THAT POINTS TO THE PASSENGER SIDE. Once you find it push it DOWN TO RESET IT and then with a finger under it PULL IT UP TO SET IT. It will click into place and stay there.
If you want to wait to put the access panel door back on and go and try the generator to see if all is well, then there is no problem leaving it off until you go inside and turn on the generator and if it was the fuse make sure it starts and if it was the circuit breaker to make sure you now have power. Then crawl under again and put the access panel back on. You have to push up the two buttons again and put the top in first and swing the bottom into the Onan to close the panel - once set in let go of the buttons and if they don't want to go on their own - push them down to lock the panel on.
IF you changed the fuse and want to start the generator with the internal start switch - shown above - you can BUT the generator when it starts is going to vibrate and you do not want to have your hands or your head anywhere close to it. I don't recommend it having done it.
WHY DID THE FUSE BLOW? The generator may have overloaded when starting. When the generator is being difficult to start - do not just keep holding onto the start switch inside the Roadtrek. Let off the switch - wait a half minute and then push the button again. After several attempts to start it - let is sit for ten minutes and then try again.
WHY DID THE CIRCUIT BREAKER TRIP? This can happen if a load over 2800 watts is put on the Onan - A/C turned on and then the Microwave is turned on at the same time. AC is running and a hair dryer is plugged into an RT outlet and turned on.
BUT IT IS VERY COMMON FOR THE BREAKER TO BE SHUT OFF WHEN ANYONE - PRO OR OWNER DOES ANYTHING INSIDE THE ONAN - INCLUDING JUST CHECKING THE OIL.
What happens is the set breaker handle is located close enough to the top of the open space that hands easily hit it down and turn it off. I have been at an Onan shop and when they told me it was ready and aI went inside to turn it on and make sure - and the Onan is running - great! - BUT the microwave display is dark (this is a quick place to look to see that you have power as when plugged in or running the Onan the display is lit - even though the microwave is not turned on. I turned on the A/C just to make sure - A/C - it did not start - just like it was dead - which it is without any 110/120 volt electricity. I called the service tech back over and told him to go under again and put the breaker back on - as he obviously hit it when he was working inside. He was not happy. They hate going under to work on it also.
WHAT IF NEITHER OF THESE WORK TO FIX IT?
The least expensive thing to have happened is a connection from either the fuse or the breaker came off of the Control Board. This happened to me - found by an Onan service tech - we both thought it was the breaker but a wire from the breaker came loose on the control board inside the Onan. Worst case is there is something much bigger wrong with the Onan. ======================
The last time I had my Onan in for service I watched the service tech go under in a different way to work on the Onan. He rolled under on a mechanic's creeper from behind the driver's rear tire from the driver's side of the Roadtrek. He was not on the ground. The mechanic's creeper lifted him up high enough to more easily look inside and get inside of the Onan. Every so often Harbor Freight stores put a nice creeper on sale for less than $30. (No I don't work for Harbor Freight and I get nothing from them for mentioning their store! (I wish I did 😉!)
The two illustrations are from the Onan KV manual. If you do not have an Onan manual, EMAIL US! and I have a KV and a KY manual that I will email you the one you need. I also have a KV service manual which is very thick in pages. I can email that to you if you ask for it - it is for the KV but the basics will apply to the KY. Be sure to tell me in the email if your Onan is a KV or KY so that you get the correct manual. These are no longer easy to find on the Cummins/Onan website.