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Re: [GMCnet] Onan No Spark [message #280742 is a reply to message #280735] Thu, 25 June 2015 23:06 Go to previous messageGo to previous message
A Hamilto is currently offline  A Hamilto   United States
Messages: 4508
Registered: April 2011
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SONICJK wrote on Thu, 25 June 2015 22:02
This thing is a bear!
New issue, had it running without the jumper and then it just died. Haven't been able to restart it since. No spark again!

After fiddling with it I have found that the only way I can get spark is by touching the top right relay on the control board. When I open and close the contacts I get a spark. Opening and closing the points does nothing.

Any ideas?
Here is everything I know about the Onan board. I plagiarized it from a GMC data store somewhere. Original credit goes to the late Duane Simmons.

Pins 1 to 6 have two pins each, one across the top to connect to the remote and another down lower, mixed in with the rest of the stuff.

Pin 1 is ground for the board. it is also connected to the remote, providing a ground to the remote switch.

Pin 2 is the input to the board for the remote stop function. Grounding this pin cause the board to shut off the generator.

Pin 3 is the input to the board for the remote start function. Grounding this pin cause the board to start the generator.

Pin 4 doesn't seem to be used in our application. Looks like another input into the same circuits that the oil pressure switch connect to.

Pin 5 is FUSED 12 volts from the battery.

Pin 6 has 12volts (fused) only when the generator is running.

Pin 7 is the ground side of the coil of the start solenoid. Grounding this point should cause the starter to engage.

Pin 8 is an A/C "generator running" input to the board from the flywheel alternator. (The other side of this AC signal is pin 5.) It disengages the starter and "latches" the voltage provided to pin 9.

Pin 9 is the output of the board to BOTH the ignition and the fuel pump. If there is voltage here, the pump should be running and the points/coil should have power.

Pin 10 has 12volts from the starter solenoid when the starter is engaged. It provides power to pin 9 when starting.

Pin 11 is UN-FUSED 12 volts from the battery.

Pin 12 is the input of the board from the oil pressure switch. The switch applies a ground when there isn't oil pressure. Just disconnecting this pin disables the function.

NOW for the methods of jumping (bypassing):

The main differences in jumping is where the power comes from, all of them connect to pin 9 (electrically the same point as the + side of the coil, the fuel pump and the fuel shut-off solenoid):

Method 1.) Some jump from pin 11 but it is better to use fused power on pin 5. If pin 11 works but pin 5 does not, look at the fuse.

Method 2.) The most popular spot is pin 5. You still use the button on the board to get the starter to turn. But you need to un-jumper the pins to turn off the generator.

Method 3.) Relatively unknown method is pin 6. This disables the generator running and low oil pressure functions but maintains BOTH the start AND STOP functions of the board. As the lower pin 6 is right next to pin 9, a short one inch jumper can be left in place with the cover on and genset pushed back in the "Onan-hole." Be aware that if you try to start the generator but it doesn't start, there will still be power to the pump and ignition until you press "stop." While all methods keep the power on pin 9, it is just easier to forget without a wire hanging off the generator.
 
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