Added a remote Onan switch

B

Bruce Hart

Active member
Oct 18, 2011
1,414
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Installed a primer switch on the inside remote panel. Activated the primer switch, start switch and Onan fires right up. When I release the prime
switch the Onan dies. I have compared my wiring to the write up on following article:

http://bdub.net/gmcmotorhome.info/onan.htm

Thinking that it could be a bad start/stop I replaced it and got same results.

Any ideas from the crowd?

Powered the primer switch from exterior light switch just inside door(Purple wire).
Remote Onan switch has a run meter and no battery condition meter. On the control board # 5 pin has a wire connected to it and not to #6 which manual
and tech write up suggests.

Power Drawer Operators Manual page 8 and 9
--
Bruce Hart
1976 Palm Beach
La Grange, Wyoming

Genetically Modified Chevy
 
Did you interrupt the power to pump/coil with your add on?
That said not a fan of prime button. Look at the size of the pump compared to the tiny carb bowl. 5 seconds of DRY bowl cranking fills it and it
starts. If the float sticks from long disuse, it will start then flood out and die. Leading you to investigate. With the button you can keep
pumping fuel unknowingly.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
So glad to hear from you, Bruce! Glad you've conquered whatever threat it
was to your health.

I had the same symptoms once. It was one of the components on the board
gone bad. I was told that the prime button was the same as jumping 5 to
9. When you release the button, it's the same as taking off the jumper.
Jump 5 to 9 to see if that works. If you've got a spare board, try that.
If you don't have another board, contact me OFFnet.

bdub

> Installed a primer switch on the inside remote panel. Activated the primer
> switch, start switch and Onan fires right up. When I release the prime
> switch the Onan dies. I have compared my wiring to the write up on
> following article:
>
> http://bdub.net/gmcmotorhome.info/onan.htm
>
> Thinking that it could be a bad start/stop I replaced it and got same
> results.
>
> Any ideas from the crowd?
>
> Powered the primer switch from exterior light switch just inside
> door(Purple wire).
> Remote Onan switch has a run meter and no battery condition meter. On the
> control board # 5 pin has a wire connected to it and not to #6 which manual
> and tech write up suggests.
>
> Power Drawer Operators Manual page 8 and 9
>
>
 
The prime switch you added is doing what it is suppose to do. It supplies power to the pump, fuel solenoid (if you have one), and the ignition. What
you have is a problem with either the "up to speed relay" not energizing, or the oil pressure sensing switch or their circuits.

So shoot the problem ignoring the fact you have a prime button / switch.

The way the prime switch works is when you press the START switch the starter motor should crank, while power is supplied to the pump, ignition,
choke, and fuel solenoid. When you release the START switch, the up to speed relay should be energized to keep power supplied to the pump and
ignition IF there is oil pressure present. You need to figure out why this is not happening. I could guess at several things as to why this is not
happening, but I would prefer you diagnose the problem rather than guessing.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
To add to KenB's reply, another place to check is the engine alternator voltage to the control board. There is a small alternator under the flywheel
which provides an AC voltage to Pin 8. This voltage tells the control board that the engine is running by energizing relay K2 which then provides
power to K3 which provides power to Pin 9 which runs the fuel pump and ignition coil.

Check the alternator voltage from Pin 5 to Pin 8. It should be 25-30VAC with the engine running.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Ok, disconnected the primer switch, pulled out the generator, jumpered from
the battery connection on onan starter and to the plus side of the coil.
Hit the start button on the generator and it fired right up and
kept running when I released the start button. So the stator is doing its
job as well as the circuit board. My problem is from the remote side of the
circuit. There is a blue wire from the harness behind the remote switch
that is connected to the ground spade of the remote switch and is hidden in
a wire loom that runs to the switches at the door. Is this typical of
remote switches to have two wires connected to the ground spade of the
switch?

> To add to KenB's reply, another place to check is the engine alternator
> voltage to the control board. There is a small alternator under the
> flywheel
> which provides an AC voltage to Pin 8. This voltage tells the control
> board that the engine is running by energizing relay K2 which then provides
> power to K3 which provides power to Pin 9 which runs the fuel pump and
> ignition coil.
>
> Check the alternator voltage from Pin 5 to Pin 8. It should be 25-30VAC
> with the engine running.
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Bruce Hart
1976 Palm Beach
LaGrange, Wyoming
GMC=Genetically Modified Chevy
 
So when you "jumpered from the battery connection on onan starter and to the plus side of the coil" you made the same connection as the Prime Switch
does. This jumper will bypass the control board and so is not an indication that the flywheel alternator is working.

Start the Onan using your jumper as above, then measure the voltage between pins 5 & 8 on the control board. You should read between 25 to 20 volts
AC... yes AC NOT DC.

If you get that reading, then pull the wire on pin 12 and remove your jumper. If then engine continues to run, then get a new oil pressure switch. If
it quits and you have the correct flywheel alternator voltage, then you likely need a new control board.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Thanks everyone for your suggestions, what it turned out to be was the switch on the power drawer itself would stick closed and not return to center
position. All is well now, remote works like charm!!!! :) :) :)
--
Bruce Hart
1976 Palm Beach
La Grange, Wyoming

Genetically Modified Chevy
 
Bruce,
Now that you have your issue solved, try this trick for smoother Onan starts.

To Start after a period of non-use (carb bowl is empty)
- Press and hold the Prime button and listen for the sound of the fuel pump to change (mine gets quieter)
- Fuel pump is now primed and pumping fuel
- Continue to hold the Prime button and listen for the fuel pump to change sound again (fuel bowl is now full and fuel pump is dead-heading against
the closed needle valve.
-Now continue to hold the Prime button and press the Start button.
-Once the Onan engine fires, continue to hold the Prime button until the engine is up to full speed
-Now release the Prime button and the engine will continue to run.

If you are re-starting the Onan and it fires then quits, the relays on the control board may not be picking up fast enough. In that case simply press
and Hold the Prime button, crank and hold the Prime button until the engine is up to full speed.

The Prime button simply bypasses the Control Board (same as connecting Pins 5 & 9). Holding the Prime button while Cranking and up to full speed
simply makes sure the ignition gets a continuous supply of power throughout the startup.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Since I don’t have a schematic of what you did, I would say one thing to check, that is good to check anyway, is the Molex behind the Onan. If you
still have it, it can have green dendrites causing leakage between circuits. Some conductivity between STOP and GRD could cause mysterious behavior.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
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