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First unplug the remote wires. This will give you one less thing to worry About at this time.I have seen shorted remote wires before. They can be a real pain to check out.
Next remove the cover on the control box. You will find the start solenoid. It looks like a Ford solenoid but it is not the same.One side will be to the battery. One side large post goes to the starter. I would take that wire off so you can do some test. If you have a volt meter or a 12 volt test light.Put the probe on the starter side of the solenoid. When you press start,you should have 12 volts on that side. If not check the battery side for voltage. If it is there. Check the S terminal. While holding it in start.If you have voltage but none on the starter side. You have a bad solenoid. You should hear the solenoid click.
If you will go over to smokstak Onan section. Post the full model and serial number. One of my guys can send you the service manual.It has all the test you need to check things out. It is not that hard to do. Plus you may save yourself some money.Just basic hand tools is all you need. Plus a good volt meter or a test light. If you need to talk call me. 903-536-2816.Let me know what you find.