| Onan issues ... [message #174080] |
Wed, 20 June 2012 16:12  |
amdgmcman
Messages: 76
Registered: April 2007
Location: Long Beach, CA
Karma: 0
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Greetings,
In 2009 I was preparing to leave on an extended trip in my 78 Royale w/ 6k ONAN gen. I took it to Miguel at MGM to have work done and he as part of the service he replaced the circuit board on the gen with a used one out of a old Onan. It worked fine at first but when I got it home it would not start. I called and he told me to jumper numbers 9 and 11 on the board then jump the solenoid to start it. I left the 9-11 connection which kept it running then when I wanted to turn off the gen, I would remove the jumper and the gen would stop running. He said it was the oil sending unit that was bad.
I was running behind on my departure time for the trip, so I used this method to operate the gen on my trip. I continued to use this method to run the gen until recently the clips and wiring I was using to jumper it corroded and I made a new set to use. The old jumper had plastic/rubber over the clips to prevent unwanted grounding, but used bare clips for the replacement jumpers. I jumpered 9-11 then went to jumper the solenoid when one of the clips, came loose and touched the chassis. This caused the clip to weld itself to the chassis and by the time I was able to dislodge it I saw smoke running through the wiring and to the starter itself. The whole unit was totally dead at this point.
I have replaced the solenoid, bridge rectifier, oil sending unit, and starter, and the unit is still dead. EXCEPT ... I found out that the 12v hot wire running from the starter to the right side of the solenoid was dead so I replaced it and power is now running to the circuit board. The unit is still dead, but I notice that if I jumper the solenoid the starter will turn over, but the gen will not start. Have I wired the solenoid wrong? Do I need to replace all of the wiring in the starting system? (too big a job for me)! I have a GMC Motorhomes International Onan Operators Manual, but can’t find a wiring diagram for the solenoid. I believe when I replaced the solenoid I hooked up the wiring the same way as the old solenoid was wired, but I’m doubting myself at this point.
Boy … do I miss Duane Simmons (RIP) … any suggestions?
Thanks,
AMDGMCMan
Alan M DeLuccio
78 Royale with
Coachmen,Center Kitchen Floorplan
09 Harley Davidson Street Glide
65 Corvair Monza Convertible
96 RAV4 2 door Manual 4WD
Long Beach, CA
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| Re: Onan issues ... [message #174113 is a reply to message #174080] |
Wed, 20 June 2012 19:11  |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| amdgmcman wrote on Wed, 20 June 2012 14:12 |
... to jumper numbers 9 and 11 on the board then jump the solenoid to start it. I left the 9-11 connection which kept it running then when I wanted to turn off the gen, I would remove the jumper and the gen would stop running. He said it was the oil sending unit that was bad.
I was running behind on my departure time for the trip, so I used this method to operate the gen on my trip. ...
... I saw smoke running through the wiring and to the starter itself. The whole unit was totally dead at this point.
I have replaced ....
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Unfortunately jumping from pin 11 bypasses the fuse and it is very possible that you have fried something.  For future reference, when trouble shooting, jump from pin 5 and be protected by the fuse.
While it doesn't help you now.... I'll continue, mostly to help others that have Onan issues in the future:
Sad thing is that if the oil pressure switch was(is) truly "bad," all that was needed to "get by" was to disconnect it. (It ground the board when there is no oil pressure. Disconnecting it removes the ground.) The Low Oil Pressure input is pin 12. It is right above the fuse next to the switch. See this picture... Note: The board is upside down from how it is installed:
<http://www.appliedgmc.com/products/full/628.gif>
IF there is something wrong with an Onan board or the safety systems that control it, I DO NOT recommend using jumpers to make the Onan run.
--- Clip on jumpers are for trouble shooting ONLY! ---
amdgmcman has just demonstrated one of the reasons to NOT use jumpers as a "long term" solution.
Now that I have said that... I'll tell you how to operate the Onan WITHOUT ANY of the safety features that the board provides.
JUST BE SURE THAT YOU UNDERSTAND that ALL safety features are DISABLED. If the Onan stops running and the switch was not selected to OFF the pump and ignition will still be powered. (Just like when you have installed jumpers on the Onan.)
Take a short (an inch or so) piece of wire with female spade connector on one end. Strip the other end. Put the connector on the lower pin 6. (Normally not used and labeled 6A in the above picture.) Disconnect pin 9, right next to pin 6A. put the striped end under pin 9 connector and reinstall... connecting pins 6A and 9. This connects the power that is normally applied to run-time-meter (RTM through upper pin 6) to the output of the board powering the fuel pump and ignition.
The Onan should start and stop with the switch just like if it did not have a problem. Just remember to TURN IT OFF if it stops for any reason other than being turned off.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: Onan issues ... [message #174139 is a reply to message #174080] |
Wed, 20 June 2012 21:49 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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If you have to make a jumper use an insulated push on terminals. The alligators are best left in FLA.
John Lebetski
Woodstock, IL
77 Eleganza II
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