Onan E-QD, reversed polarity on start battery

[Southern Boater]

This has been reposted from the Electrics category, after re-reading the headings!

Hi all, can anybody advise on the following issue please.

After an Onan EQD genset 2005 model start battery was hooked up in reverse polarity, a start attempt was made with no ignition of course. Then wired correctly, the engine started, ran for a few seconds, shuts down with “error code 36” which means unknown shutdown, the controller declared this fault because engine speed fell below 1000 rpm for 0.5 seconds.
It then goes into a corrective action list which is all fuel related, which I don’t believe is the cause because the genset has been running fine prior to the reverse polarity issue with the start battery.
Question is, has something electronically been compromised, the error code seems very generic with its “unknown” ID. Is the system fuse protected? Any suggestions?

Thanks

 

[High Wire]

Going to take a guess that this generator has a speed sensor that is no longer working. The speed sensor trip would be bypassed on startup and after a time delay to allow a good start, the low speed trip would be enabled. If the sensor was bad, as soon as the bypass unbypasses, then the ECM would see zero speed and trip the unit. See if you can find a wiring diagram that might show a fuse or at least a way to bypass the trip temporarily for troubleshooting. It could be the entire trip circuit is dead. It would work pretty much the same way.
In older generators there is only one control power fuse. The trips are bypassed until you let go of the start switch.

 

[Southern Boater]

Thanks for the reply.

It appears the electronic versions have the voltage regulator, for example, encapsulated within the Control Card/circuit board, and I’m suspecting the reverse polarity event has damaged components on the battery charging side. This would mean replacement of the control card at the least.

It would be good to hear from any others who have had the same issues.

 

[Southern Boater]

Just to close this thread, and after waiting six months for the replacement part, by reversing polarity and initiating the start sequence, the control card/board was damaged and needs replacement.
The circuit boards were/are very hard to source through the dealer network due to global supply issues. The cost in Oz was $AUD2,000, so an expensive lesson in not to reverse polarity on the start battery, let alone the massive wait for the part.

One thing that was found out during this process, and not through any dealer knowledge, because that is very limited in this country, the boards are generic and suit all of the MDKB… series gensets, both single and three phase, but need to be configured to any of the specific gensets.
All instructions are downloadable from the internet from www.seapowermarine.com
Onan Service Manuals, Technical library.

 

[TowLou]

I was gonna suggest look at deep sea for a new controller. Yes many controllers are plug and play as well.

 

[Southern Boater]

I was gonna suggest look at deep sea for a new controller. Yes many controllers are plug and play as well.

Because this genset is in exceptional condition for its age with low hours, I was trying to keep it original, but since learned of the options to bypass the OEM controllers, as long as all the sensors are duplicated to protect the engine and alternator from damage.