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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15280
Experience:  Certified on Onan and Generac generators
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How do i clear a low voltage fault on my onoa gen set.

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How do i clear a low voltage fault on my onoa gen set.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: generater battery went and i used the booster from the coach batteries generator started but quit when i let off on the booster now throws a low voltage code and wont ingage.
JA: Do you have fuel in the tank? If so, is the shut-off valve open and the fuel clean?
Customer: yes
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: no

Hi, my name is***** me review the issue, and I will be more than happy to help resolve it as quickly as possible. I will return in under 5 minutes



Sir, my name is ***** ***** I am a certified Onan technician.

You were given incorrect information here.

Once a code has been set in the controller, there is no way to erase it. The ONLY way to completely get rid of a code is to install a new controller - but even that will end up with a code once a problem has developed.

The code may be overwritten by a new code later, but there will always be a code showing from now on.

The problem causing the low voltage situation needs to be corrected for the genset to run, but the code will remain.

Hank F., Technician
Category: Small Engine
Satisfied Customers: 15280
Experience: Certified on Onan and Generac generators
Hank F. and 2 other Small Engine Specialists are ready to help you
Customer: replied 2 months ago.
I assume that the low voltage fault occurred because the batterys were dead. the batterys are now charged and still will not do anything.

As per our phone conversation, let me know what you find.

When you reply, I will also need the full model number of the genset. There are a few different variations of the HDK series.

Customer: replied 2 months ago.
Hank i checked the voltage at the generator and it is 12.4 volts. The voltage did not change when the start button was pushed. tried the primer button but could not hear any noise. Model number is *****


What was that code you were getting again?

Customer: replied 2 months ago.
code 46


On the gen control panel, right above the start switch, is a small panel held on with a single 10 mm bolt.

Remove that bolt, and remove that panel.

There are 3 fuses behind the panel.

Check all 3 fuses to make sure none of them are blown.

Let me know what you find.

Customer: replied 2 months ago.
they are all fine.


As you are looking at the genset, on the left side there is a connector with 8 small wires in it.

Unplug this connector, and try to start the gen with the switch on the gen itself.

Will it crank now?

If not, here is what you need to do next:

Remember, as you are facing the genset, the front panel is actually the panel to your right - the large green panel.

Some gensets have a door in the front panel. If yours does, remove that door, if you have access.

If it does not have a door, the panel will need to be removed.

Inside, at the starter, test the large battery cable to make sure you have 12V there.

If you do not, the cable is broken between there and where it connects to the genset.

If you have good voltage, there is a small wire attached to the starter solenoid. This wire will be labeled K1-S. Test this wire for 12V while pressing the start switch.

Is 12V present there?

Customer: replied 2 months ago.
Unplugged 8 wire plug and still no start. Checked big wire and had 12.3 volts checked small wire to solonoid while pressing start button and no voltage.
Ok. At the back of the start switch, locate the wires labeled S1-1 and S1-3, or they may be marked S1-A and S1-C.
Use a jumper and jump across these 2 wires. They are grounds, so will not shock you.
Does this cause the unit to crank?
Customer: replied 2 months ago.
Hank there are 5 wires in the switch. none with your numbers.These numbers are what is on each wire.
P9-3 P2-12
P9-2 P2-11
GND P-9-7
P9-1 P2-10
P9-8 P1-5
Customer: replied 2 months ago.
Here is a picture
Someone has taken the adapter off, or it was never installed.
The wires you need to jump are GND and P9-3.
You can take a paper clip or a short piece of wire with both ends stripped, and just shove it down into the switch housing to jump it.
Customer: replied 2 months ago.
Nope nothing.
If that did nothing, you either have s broken wire between the switch and the control board, or the control board is bad.
Customer: replied 2 months ago.
Ok, so where is the control board and is that something i can change.
Customer: replied 2 months ago.
Is it something I can replace and where is it located.

Sorry, things went to pot at work this afternoon, and I was not able to check in here at all.

The control board on this unit is called an inverter.

It is located below the black end cover, below the start switch.

Yes, it would be possible to change it yourself, but major disassembly is required. The front and left end panels must be removed, and this may require removal of the genset from the coach.

It is also a very expensive item - about $2000.