Onan power drain when off

[Tireman9]

It has taken me a long time to diagnose and trace this problem but I have finally confirmed that the Onan 4KY genset is drawing 3.85 Amp even when off.
My system uses the shore power cord to plug into a receptacle to power the RV off the generator. However I have traced a power drain off the coach battery to the large Ga wire that runs directly from the genset to my coach battery. I am guessing this is the wire that would run the starter motor on the generator.
I have a wire diagram from Coachmen but it has no details. Manuals and literature from Onan and Coachmen are of no help and of course I am now 6 weeks out of warranty.

Why would there be a power drain to the generator starter circuit even though the coach battery is supposedly disconnected using the onboard relay?
This of course means the starter switch is not capable of starting the generator.

[RV Wizard]

I am not sure of which model you have but if you can unplug the remote start circuit from the generator, it may be the issue. Let us know what you find.

[Tireman9]

Quote:

Originally Posted by RV Wizard I am not sure of which model you have but if you can unplug the remote start circuit from the generator, it may be the issue. Let us know what you find.

I have a 4KY. I have traced the "short" or whatever is causing the 3.8 amp drain to the 12v wire labeled CSG on the Coachmen circuit diagram. This diagram has 5 wires coming from the schematic for the generator.
1. CSG which is about 2 Ga (battery cable size) that runs to the 250A main fuse that is connected to the Ground
A three wire connection w/ wires GHR, GST, GSP These run to the "command Center" which has the remote start switch in it.

I have not tried the remote start circuit as I found the drain through CSG but will give the remote circuit a test.

Here is layout of 12v in coach



Here is Gen schematic. You can see Battery BT1 at top. They do not show the external wire CSG but it must connect between R1, BT1, K1 and F1.

[RV Wizard]

CSG is the same as the positive battery cable from the house battery and should not be connected to ground. BT1 is the same as the house battery.
GHR is the generator hour meter circuit.
GSP is the generator "stop" circuit.
GST is the generator "start" circuit.

[John Hilley]

The diagram that you made is the way the circuits should be. That is a very large drain. Does your battery drain down over one day? Could some thing else be connected to the generator starting circuit?

[Rvpapa]

If you have a bad diode in CR1 (genset battery charger) your problem will happen. The drain is through the stator charging circuit.
Art.

[Tireman9]

Quote:

Originally Posted by Rvpapa If you have a bad diode in CR1 (genset battery charger) your problem will happen. The drain is through the stator charging circuit. Art.

RVpapa The good news is you confirmed what I thought after disconnecting the wires in the Onan at the starter solenoid. with ohm meter I confirmed an ever increasing resistance so I figures it was not through a bad connection or resistor but a capacitor or some other element that took mpwer. Looking at the diagram that left CR1.

Bad news is I'm 6 weeks out of warranty and the circuit board if $350


Wish I had started chasing this down a few weeks earlier and I might have put in a claim. Oh well that's life when you own an RV.

[Rvpapa]

Tireman9,
It's been a long time since I worked on a small genset, but I think that the CR1 is a separate diode bridge that can be repaired (a new one from Onan will cost).
OTOH you don't really need it. Just disconnect at R1 and the converter in the RV will keep the battery charged. It is only really needed for a stand-alone genset.
Art.

[Tireman9]

RVpapa
According to the info I have, my genset has the "improved" control module with all that stuff intrigrated and potted in one piece. I have read threads about just replacing the bridge with a $8 part but those were different models.