Onan info

[Rich Biebel]

Bad contact between the brushes and slip rings is one of the biggest things that can cause an issue like you have Jeff. If the brush does not contact the slip ring it will arc for a while and the arcing damages the surface of the copper......Clean it with some shop roll paper untill it is as clean as you can get it.

I have been working on a Miller 300 D Trailblazer-Diesel welder. Already have hours and hours in it, changed the rotor and PC control board.....and the board was already replaced once 6 months ago.....Weld output is intermittent at best.......I spent a good part of today trying to nail down the problem and find nothing that is clearly wrong.....but it doesn't work and I already have a pile of money in parts in it and a pile of time.....

Working with machines that produce electricity can be very very difficult....even for people that do it all the time like myself....

Hopefully you found your problem.....

[Jeff Niceswanger]

Well Well Well
Spoke too soon, I thought I had it fixed, but now it sets a different code, and still won't run without holding in start button. I now have hertz( 61 while holding button down)). I even have 14-20hz while the motor is being cranked, but I get a code 32. Low hertz while being cranked or something like that.Went ahead and PM'ed it while it was out. Plug, fuel filter, oil etc...I stuck it back in the back of the mini van and I going to take it to the dealer Monday. I checked everything I can think of, Stator/field ohms out (@35) perfect, brushes/rotor are 21 ohms. I have cleaned and tightened grounds and checked pins till I have had enough of it. I even stuck the old controller board back into be sure .. Same 32 code... I'll let you know what they find out.....

[Rich Biebel]

Working with machines that produce electricity can be very very difficult....even for people that do it all the time like myself....

I already said that but have to repeat it.....

Trust me when I tell you I have been there and done that as the saying goes....

I worked on a buddies 4KY earlier this year at home for the better part of a week at night after work.....I was just about to throw in the towel and than gave it another try.....Got it fixed and he is still using it now....probably today as there is a big race at Atco......

That code is a bit odd....Stators can test ok with an ohmeter and still cause problems.....Ohm testiing is not conclusive and I deal with this all the time..

Hopefully you found a place that can get it fixed for you...

[supergas4]

how about a code 47 on a 5500- marqie

[Rich Biebel]

Originally Posted by supergas4

how about a code 47 on a 5500- marqie

Code 47
Points to the ignition coils and wiring between them and the controller.
The coils are magneto style.....they make spark anytime the blower wheel passes them. They are grounded by the controller thru a small wire attached on the coil. Code 47 says the controller is not connected to the coils.

My experience tells me this is likely not the problem...and getting to the coils is a major job as the unit has to be completely disassembled....

I would check the white wires going down to the coils. They both have a connector on the upper section side. The controllers on these machines fail a lot.......That is more likely the problem....

It is a PC board in a holder/tray located inside the box where the start/stop is.....One weatherpak style connector......Those connectors can also cause problems....

[Rich Biebel]

Well today I removed a CMM 7000 EFI unit for random shutdowns.

Bench tested it under load untill it failed...

Showed a Code 47 fault. Did it more than once.

I checked the coil connections to the controller and all was fine as it always is...

Installed a NEW 300-5047 Controller and continued to test the unit...

Ran the rest of the day on and off with various loads applied and no more shutdowns...

So for the umpteenth time a controller is at fault and the fault code it showed was somewhat misleading.....

And during the time I worked on this unit another customer came in with a similar problem......He may or may not be getting a controller also but he opted for a wait and see deal as we cleaned some wire connections....

My money is on him returning before the week is out to get the controller replaced.....and regretting not doing it today.......

[erkme73]

Ok, here's my latest update.

Backstory:
My 7000 Marquis (gas) has been shutting down randomly WITHOUT generating any error code. As documented in my posts above, the unit would shut down abruptly as though someone had pressed the stop button. The reported error code was always an old code from a previous abnormal shutdown (i.e. low oil, fuel delivery).

Discovery since last post:
I removed the control module to inspect it carefully. The open side is filled with a clear epoxy/silicone material designed to encapsulate the circuit board and keep it dry. There were several pronounced cracks in this silicone in the corners. The cracks were deep enough to reach the PCB - and in one corner, the board and silicone were rusty colored (picture attached).

Actions:
Figuring moisture ingress was the likely cause of the intermittent shutdowns, I carefully and methodically stripped the silicone off of the board using a small flat-headed screwdriver. The glue came up surprisingly easily. I was unable to remove the PCB from the housing since the glue between the board and the housing was inaccessible. I then put the the module in my toaster oven at 175 deg F (no, I'm not kidding). I let it bake for an hour. As soon as it came out, I filled it with clear GE silicone II caulk from Home Depot for about $6 (picture attached). I let it sit overnight. The following morning, I reinstalled the control module in the genny, and let her run.

Results:
It's now been running for most of the morning without a single shutdown. While this doesn't mean anything (the random shutdowns sometimes went many hours between events), I'll let it run all day (and into the night if need be) to confirm that the shut downs are eliminated. I will post back my results once the testing is completed.

Given that my situation seems unique (shutdown without error code), I don't know how much my troubleshooting will help anyone. However, at a minimum, if you've performed all the possible diagnostics and are left with replacing the ECU, before you do, inspect the sealant carefully. Unless something is toasted on the board, you might just be able to revive it.

I figured I need a new board anyway - so I'm not going to break it more than it's already broken. Besides, I can learn more tricks this way

[Rich Biebel]

The part number is 300-5047 for that A-1Controller as Onan calls it...

The boards fail regularly and there is NO visual area to see that is faulty.

They generally fail with heat and I let a unit run on my bench for a while with a resistive load bank connected to it....

Once it is good and warm.....I shut it down and let it sit for a while....It heat soaks so to speak. Any unit that has had intermittent shutdown problems will usually start to do it once I put them thru this test. As soon as the unit starts to shutdown......I replace the PC board/control and continue the same test and the units no longer shutdown...

I did 2 units this week.....

One got a new engine and a controller...
One got just a controller......

We called a company we deal with that does PC board testing and repairs....They do a lot of boards for us and also make some lower cost replacements for many common parts. They don't do this one.....

I have changed probably 15-20 of them in the last 5 years....

My prediction is you will be changing yours as well......

[erkme73]

Rich, you may be right, but for $350, I'll take the chances that it was moisture getting to the 'rusty' part of the pcb. See the photo showing the large deep crack in the original sealant. After drying it out and resealing it, I've got 6 straight hours on it now, and it hasn't skipped a beat.

I just upgraded my 36' Damon gasser (the source for this generator) to a 42' Tiffin Phaeton diesel pusher. It has a 10k quiet diesel onan.

The only reason I want to get this genny fixed is so I can sell it to the next guy with a clean conscience. I'll let the buyer know that if the generator starts to shut down without error, they'll need to buy this controller.

[Rich Biebel]

Those PC boards sell for $450 and I have seen them sold on various websites for over $500

I have seen the potting material split and cracked as you described.

Moisture is definately not a good thing for a PC board to be exposed to...

If you got it working with no shutdowns.....great.....