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Onan 3.2 HDZAA-6508B (aka Cummins-Onan RV QD3200) runs fine for ~3 minutes, then dies

sajohnson

Registered
We have a Cummins-Onan RV QD 3200 diesel generator, mfrd in 2008.

The generator starts and runs fine -- for 3 minutes and then shuts down.

Every time.

It has run perfectly in the past, this is a recent problem.

There are no error codes.

We've been to Cummins shops in Billings, MT, and Sioux Falls, SD. The folks at both locations were very friendly but unable to fix the problem.

I changed the fuel filter but the problem remains. Genset runs for approx. 3 minutes each time then shuts down.

It does this regardless of the load -- full, partial, or no load.

It will restart immediately after it dies and run for another 3 min.

Clues:

1) The remote control panel _always_ says "Generator Off" (Gen Off), even when it's running.
2) The remote control panel has a 3 minute timer. If the operator turns the panel on, but does not hit 'start' within 3 minutes, it times out and the display goes dark.

It's as if the control circuitry doesn't recognize that the generator is actually running and it shuts the genset down when the display goes dark.

I replaced (temporarily) the control board on the genset (#300-6414) at Cummins in Sioux Falls -- no change.

The guys at Cummins in Billings, MT, were nice enough to print out a copy of the service manual for the QD 3200 for me, but it isn't very comprehensive.

I'm thinking that the remote control panel (#300-6411) may be the culprit, but I'm hoping it isn't because $400 is a lot of $$ to this retired tech.

Anyone else have this problem?

Any thoughts or suggestions?

Thanks.
 

EricWood

Subscriber
Last Subscription Date
10/15/2019
Do you have the service manual? If not, Send a PM with your email address.

Using the attached diagram, I'd check that your AC1/AC2 signals are getting to the remote panel.
 

Attachments

EricWood

Subscriber
Last Subscription Date
10/15/2019
Oops...missed you already have the service manual. Yes, one of the less informative ones!
 

sajohnson

Registered
Eric,

Thank you!

The service manual that the guys in Billings gave me has that same diagram.

We're on the road (currently just to your south, in Clear Lake, Iowa) but I do have a meter with me. I can check AC1 & AC2 on pins 10 & 11 at the connector on the back of the remote panel but what sort of signal am I looking for?

I assume I should check from #10 to ground (#1), and #11 to #1?

~~~~~

PS: I really appreciate your help. I have two new Crown CR260 GC batteries, a couple solar panels, and a Magnum MS2000 inverter but without the generator we're kind of crippled. The panels are only good for maybe 10A on a sunny day and for some reason the 2008 Sprinter cab-chassis charging system is only putting out about 13.5V max. The AGM chassis battery is charging perfectly (12.7V), but the two GC batteries are only getting a partial charge.
 

EricWood

Subscriber
Last Subscription Date
10/15/2019
Yes, Ohm to pin 1 at the remote panel plug to ground and verify good ground coming through the cable. Verify good B+ at pin 12.

Pins 10 and 11 should have an AC signal when running. It comes from an "Auxillary" winding in the generator.

I guessing it wouldn't be protective shutdown-related at this time, due to it running until the display timer runs out, plus it never figures its really on. But the DC side must be operating correctly, to keep the elec. fuel pump going.


eric

---------- Post added at 04:14 PM ---------- Previous post was at 03:50 PM ----------

As far as voltage level, I don't know...no published spec that I have available to me. Only spec is in the manual, at a ohm reading of 0.3 ohms for the aux. winding check. I'm guessing that sense it goes through the controller, you would see a lower, transformed voltage at the remote panel. If no voltage is present, you need to piggyback the pins 2 and 3 from the six-pin connector from the PM gen, that plugs into the controller and see if there is an aux. winding voltage going into the controller. If voltage going into controller looks reasonable, see whats coming out of it locally before it goes through the remote cable.
 

sajohnson

Registered
Just to make sure I understand, at the remote control panel:

1) Check continuity between pin #1 and a good ground.
2) check for B+ between pin #12 and pin #1.
3) With genset running, check for AC voltage between pins #10 & #11.
4) Check resistance of aux winding. Should be 0.3 ohms.

Where would you suggest measuring the aux winding resistance?

What do you mean by:

"If no voltage is present, you need to piggyback the pins 2 and 3 from the six-pin connector from the PM gen, that plugs into the controller and see if there is an aux. winding voltage going into the controller."

These may be dumb questions but...

By 'piggyback' do you mean put test probes on them to measure the voltage?

What is the 'PM gen'?

I apologize in advance for my ignorance. I just want to confirm I understand your instructions.

Thanks!
 

EricWood

Subscriber
Last Subscription Date
10/15/2019
You'll want to check for an AC voltage at 10 and 11 at the remote panel plug (possibly have enough clearance to probe rear of plug carefully while its plugged in.

Same thing at the generator controller. The AC signal from the aux. winding comes in on a six pin connector, on the generator, to the control module you had previously had temporarily replaced as a troubleshooting step. By "Piggyback", I mean being able to probe the connector, or figure out another way to measure the voltage from the windings, while the plug is still connected to the controller (the blue wires). It would appear to me that the controller part is working with a readable aux. voltage.

To measure the aux. winding resistance, with the genset off, pull the six-pin plug off of the controller and measure across pins 2 and 3 (the blue wires).

PM generator is your main generator. Permanent Magnet Generator. Generator can put out a varying speed/power rating into the inverter, which outputs the constant 120V/60hertz power, based on actual house loads. A PM generator produces power without any external help, at varying speeds, unlike conventional generators.

These are some of the basic checks that should be looked into, based on your symptoms. I make no implication to how easy any of this is to access/perform. :O

eric
 

Elden DuRand

In Memory Of
Age
78
Last Subscription Date
12/22/2017
........ Snip...........
I have two new Crown CR260 GC batteries, a couple solar panels, and a Magnum MS2000 inverter but without the generator we're kind of crippled. The panels are only good for maybe 10A on a sunny day and for some reason the 2008 Sprinter cab-chassis charging system is only putting out about 13.5V max. The AGM chassis battery is charging perfectly (12.7V), but the two GC batteries are only getting a partial charge.
I can't help you with the generator problem but on our Sprinter based Winnie, there is a contractor (one of two) located beneath a cover between driver and passenger seats. It is called the battery boost contactor and can be identified by noting which of the two is operated by the Battery Boost button on the dash.

This contactor serves two purposes. One is to parallel the house batteries with the chassis battery in case one of them is discharged.

The second purpose is to parallel the batteries when the engine is running in order to charge the house batteries.

There are many instances where the contactor energizes (makes the "clunk" sound) but the contacts fail to make. You can test it with the engine running by noting that both chassis and house battery voltages are identical.

If you replace this contactor (which looks like a starter solenoid) BE SURE to replace it with a solenoid with a continuous duty coil rating!

A temporary fix is to jump between the contacts of the contactor but don't forget to disconnect this (heavy) jumper when stopped. Failure to do so could leave you stranded with all batteries dead after a long portion of parking/dry camping.

BTW, 13.5 volts from the engine alternator (after running for a while) is low. It should be around 14.2 volts after the batteries have charged.
 

sajohnson

Registered
Hi Elden,

Thanks for the info!

As it happens, I was made aware of the issues with the OE 'boost' solenoid that Winnebago chose to use on the View/Navion and had purchased a Cole-Hersee unit with a 200A rating to replace it.

Luckily, I remembered to bring it along and after noticing the coach battery charging issues I installed it in place of the OE solenoid. That made a difference -- it eliminated/reduced the voltage drop between the chassis and coach batteries. I say eliminated/reduced because under heavy load, when the inverter is drawing a substantial amount of current from the GC batteries (say 80-140A+) there is still a drop of about 0.5V, which I assume is due to the relatively small OE cable.

Unfortunately, there is of course still the issue with the chassis charging system never even getting close to 14.2V. I've worked on cars for about 40 years and in my (admittedly limited) experience, charging systems typically put out 14.2-14.4V. What really stumps me about our Sprinter chassis is that the stock AGM starting battery remains fully charged, with just ~13.2V on it on average. The GC batteries still need a serious topping off after driving for hours. If we happen to have a spot with shore power, the charger in the inverter will dump a large amount of current into the batteries for quite a while until it goes into float mode.

Anyway, thanks for the advice. I guess this issue is a bit off-topic (if related). I'm going to do some genset troubleshooting now, per Eric's instructions. Then, if I blow something up, I can blame him!

Will report back soon.
 

sajohnson

Registered
OK, here are my findings:

1) B+ (pin #1 to pin 12) = ~12.8V
2) Pin #1 (Gnd) to ground in 120V receptacle = ~10 ohms.
3) No AC signal present at pins 10 & 11 (with genset running).
4) ~12.4Vac present at pins 2 & 3 on control board [6 pin connector] on genset.
5) ~12.3Vac present at pins 2 & 3 on control board 10 pin connector] on genset.

It seems that perhaps the cable from the 10 pin connector on the internal control panel to the 12 pin connector on the remote control may be bad -- pink and/or violet wires may be open.

We're going up to Forest City tomorrow to visit Winnebago and probably the local dealer, Lichtsinn, as well. Maybe WGO would have a spare cable I could use between the internal control panel and the remote control panel to confirm.

What do you think? Anything else I can try?

Thank you.

[I can't yet edit my posts so...]

I forgot to mention that:

1) The 12.8V was/is significantly lower than the coach battery voltage which is being held at about 14.8V right now because the inverter is in 'absorption charge' mode due to the DC loads in the coach. 2V seems like a significant difference.

2) I have no idea why there would be 10 ohms between pin #1 (Gnd) and the grounded outlet, or whether that is normal. AC and DC systems in the RV share the same ground.

4/5) I also have no idea what the aux. winding signal level is supposed to be. Regardless, there is 12V+ at both the input and output on the internal control panel and absolutely nothing on the remote in the coach.
 

EricWood

Subscriber
Last Subscription Date
10/15/2019
Sounds like you did OK troubleshooting it. I'd suspect you have a bad remote cable too, with no AC at the far end.

As for the 10 ohms to ground, could be individual connections between your test points, plus a a little resistive ground is fairly common from digital controllers.

For the 12.8 volts, I'd guess I would need to know what the voltage is on the battery that starts the genset. The controller may be sending a current-limited voltage down the line to the remote panel, since it consumption would be small.

We'll wait and see what happens when you get a chance to swap out the cable.

You could also remove the remote cable at both ends, and ohm out wires 10 and 11. Also, you can short out pins 10 and 11 at one end, and ohm the other end. That will confirm you've either got an short or an open, depending how it ohms out.

eric
 

sajohnson

Registered
Thanks Eric, I was thinking the same thing -- short 10 + 11 at one end and check continuity of the pink and violet wires.

The voltage of the coach batteries that start the genset was being held at 14.7/8 because of the DC loads in the coach (mostly lighting) -- the inverter's battery charger goes into absorption mode.

I really appreciate your help so far, thank you.
 

Billy J Shafer

Subscriber
Age
69
Last Subscription Date
09/03/2019
Never worked on what you have. But can you not just unhook the remote cable at the genset for testing. Since it does require a signal for remote to run. Why couldn't the dealers find it.

This is why I advise people to get a service manual and do the checks.Have very little trust in Onan techs these days.

When you pull the cable out. I would look for cuts in the cable. In the old systems,that was a big problem. Rubbing on the frame cut a lot of them.
 

sajohnson

Registered
Unfortunately, in this case, the cable must be plugged into the remote control panel for the genset to remain running. When I unplugged it, the engine immediately died. I quickly plugged it back in and it started running again.

I brought a set of test leads for my meter that have needle point tips -- they were able to slip into the back of the connectors.

WRT the Cummins techs -- what can I tell you? They claimed they'd never (or rarely) seen the QD 3200 and had no training on it. Maybe Cummins treats their "Cummins-Onan" line like an afterthought? It was very hard finding parts as well. That's why we went from Billings to Sioux Falls (we were headed east anyway). Sioux Falls had the internal control panel ($244) but said the closest remote control panel ($400) was at a Cummins shop in the Chicago area!

All I can say is that I hope we don't need parts very often because they are expensive and hard to find.

As for the service manual, what the guys at the Billings shop were nice enough to print out for me has very little in the way of troubleshooting info. Nothing Eric suggested is in there. The schematic is ok, but does not include typical voltages at various points. I have no idea whether the 12Vac+ from the aux windings is the correct level, but since I measure 0Vac at the remote control I'm assuming the cable is bad. I haven't checked it yet -- heading to Winnebago now and hoping they have a spare I can use to confirm (and then purchase).

Wish me luck. ;-)
 

rmchambers

Registered
Last Subscription Date
12/20/2014
The Cummins techs are next to useless unless they were former Onan guys (like our resident guru Billy) you're not going to get a stellar level of service.

You're in the right place for talent though, it's amazing what folks on this forum have in the way of experience.

If you can provide the answers to the questions asked you're going to get pretty good advice here.
 

sajohnson

Registered
UPDATE:

Well, we finally got the cable after spending the night in a spot with electric behind the Cummins shop in Elkhart, IN. That was a nice perk (and a surprise).

The cable was about $60 including tax.

While there, I checked on the price of a fuel filter -- $82!! $82 for a little filter that looks like it might be used on a riding mower.

Can anyone tell me if there's something special about the filters that Cummins sells -- or do they just mark up RV supplies astronomically because they figure they can get away with it? The filters I bought at a auto parts chain were $5 each. The Cummins tech at Billings (or Sioux Falls) said it was fine to use, so I'm officially confused about the ginormous price difference.

Anyway, the new cable fixed the problem!

WRT the chassis charging system problem I mentioned, I traced that to a corroded/resistive "Y" cable -- a battery cable that runs from the alternator output to the starter solenoid to the chassis battery. With a heavy load on the inverter the starter 'Y' connection got so hot it burned my finger!

I just ordered a replacement cable today. Supposedly they have been re-designed. We'll see. I may end up making my own cable.

I just figured I'd report back with what I found.

I really appreciate all of the help and suggestions.

Special thanks to Eric.
 

sajohnson

Registered
Thanks for letting us know. It is always nice to know how these things come out.
No problem.

It bothers me when people don't report back after a problem is resolved, but I've been guilty of that myself.

When something doesn't work one's focus is on getting it repaired -- once it's fixed, it's 'on to the next project'.

I'm hoping that this thread will help someone else, but I gather that the RV QD3200 is rather rare, and this was an unusual problem, so it may not come up again -- unless many/most Cummins/Onan gensets (not just the small diesels) rely on an aux winding signal to indicate that they're running.

Even then, I imagine the control cables don't fail very often.

We're back home now and will be permanently installing the cable soon. I'm curious to see if the damage will be obvious. The part of the cable we can see looks fine.
 
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