Onan 8KW DKD no start at control box

[birds_first]

Maybe someone with a 87 - 89 FC with an Onan or an SP with an Onan can help with this. I am stumped that my Onan DKD 8KW will not start at the control box on top of the generator but it will start everywhere else (so far). In the past it had an intermittent problem of not starting anywhere but the control box, but now it will start in 3 places; above the driver's seat, above the door and in the bedroom but no start at the control box.
This is what I have done to check it out.
1. I replaced the start button at the control box. I have power on the center terminal on the control box start switch. At a few times today we would get a start at the control box, so the problem is intermittent.
2. I replaced both red rocker breakers. The bottom rocker breaker had tripped under the red rocker button common error for those cheap 4$$ rocker switches.
3. I initially had a weak fuel shut off solenoid but that cleared up. (Weak battery)
4. I have power at the battery of 12.8V or better, with the generator running it reads 13.5V or better at the battery so the alternator is working.
5. The generator will produce power and run fine under load with an above average demand, with both AC units on high and the water heater turned on. I ran it today for over an hour with this load. Temps are around 170 degrees water and around 200 for oil.

I need to give credit to Jay Christmas for helping me sort out the problem we spent most of the day looking into this and we were still stumped at the end of the day.

I did replace the fuel filter yesterday & the air filter but I do not see how they are related to the above problem.

Any suggestions would be greatly appreciated.

[dlefty]

Hey John,

Dealing with the control box is a pain. Since you replaced all the breakers on the box it has to be the board or all the wires attached to the board. These should be checked to make sure they haven't come loose over time. You might need to remove the entire box and put it on a bench to actually get in there. The other board itself could be shot or starting to go. Correct me if I am wrong thou, didn't you already replace this? I have a spare if you are in a bind.

The name of the place that I got my replacements from is Flight Systems.

I have a number of manuals and sheets I made up for the Onan. But I believe you have these from Hershey last year.

Here is one which I made up because the original was way too small for my eyes:
Engine_Monitor_Onan.pdf

[dlefty]

In case you or anybody else wants copies of the wiring diagrams for the Onan I will place them here. For editable diagrams please contact me.

Engine_Monitor_Onan.pdf

Relays_Onan.pdf

Remote_Guages.pdf

Start_Selonoid_Onan.pdf

start_stop_cb.pdf

[Buckeye Bird]

Sure sounds like a bad ground somewhere........

[birds_first]

Dan, It is my plan to take the control box off the generator tomorrow and see if I can find the problem, I'm thinking it has to be a bad pin in that round pin connector. I did have a new board put in last year by the Onan shop plus a few pins replaced "Ouch", plus I have a new spare board I bought from a WOG member. Thanks for the diagrams now if I only could read them, duh... Sometimes I feel so stupid; boy the joys of owning a Blue Bird I know through the help of the forum and knowing that others have gone there before me I too should be able to meet this challenge.

[dlefty]

I too was a novice until I spent a lot of time understanding how to read the schematics. It really is pretty easy.

A11 is the engine monitor board, K11 is the Start Solenoid, J2 - is the Canon Plug, J3 - is the Remote Guages, K14 - Fuel Solenoid Relay, K13 - Heater Relay, S11 - Start/Stop Switch, S12 - Preheat Switch, CB11 - DC Control Circuit Breaker, CB13 - Batt. Chg CB, & CB12 - Fault Circuit Breaker.

All the wires physically are numbered with a corresponding schematic number on where they are going to or from. For instance you look at A11 Stop and want to know where J3-2 goes. You find under Remote that J3-2 is a Stop Switch.

I don't think that your problem has to do with the canon plug. If it is fine coming from inside the coach then I would have to believe it is between the engine monitor board and the connection of the wires of the switches. If you find all the wires are snug and it still won't start from the Onan, I would replace the board. It seems like a task taking off the wires but it might be the cause...

Component Description.pdf

[markbragdon]

Originally Posted by dlefty

I too was a novice until I spent a lot of time understanding how to read the schematics. It really is pretty easy.

A11 is the engine monitor board, K11 is the Start Solenoid, J2 - is the Canon Plug, J3 - is the Remote Guages, K14 - Fuel Solenoid Relay, K13 - Heater Relay, S11 - Start/Stop Switch, S12 - Preheat Switch, CB11 - DC Control Circuit Breaker, CB13 - Batt. Chg CB, & CB12 - Fault Circuit Breaker.

All the wires physically are numbered with a corresponding schematic number on where they are going to or from. For instance you look at A11 Stop and want to know where J3-2 goes. You find under Remote that J3-2 is a Stop Switch.

I don't think that your problem has to do with the canon plug. If it is fine coming from inside the coach then I would have to believe it is between the engine monitor board and the connection of the wires of the switches. If you find all the wires are snug and it still won't start from the Onan, I would replace the board. It seems like a task taking off the wires but it might be the cause...

Attachment 22567

Thanks for the explanations, Dan. I, too, suffer from headaches trying to decipher electrical schematics. The only solution is an adult beverage.

[birds_first]

Well we didn't get the control box off today other priorities came up but we will get to it in the morning. I did attempt to start it and it started and ran again for an hour or so befor I shut it down. I attempted to start it from the control box and it wouldn't. I went back later this afternoon after it cooled down and it fired up and ran until I shut it down. It has to be in the start button circut for the control panel, we hope to find out Thursday and we'll let you know what we found out.

[birds_first]

With the help of another friend Chuck Thomas from Florence, SC who works as a electrical maintenance tech for General Electric we think we have found the culprit. Our problem wire is A-11 LOP on the inside of the box at the large round cannon plug connecter. With the control box mounted I beleave it is almost impossible to make this repair on the connector. This loose wire is in the start – stop function. The pins and plugs of the cannon plug are hollow and require a pin extraction tool, the wires depending on which side of the plug are inserted into a plug or pin, both are hollow. If installed improperly the wire will back out or vibrate out and connection is lost. What I and most people with an Onan in an FC will tell you there is excessive vibration of the control box since it is mounted onto the generator. When you start or stop the generator it shakes excessively and I believe that is the root of most all problems with broken wire connections. So to eliminate the vibration of the control box I dismounted the control box from the generator and made a casing for the control box to slide into. The casing box is mounted to the top of the generator compartment. When the generator started for us with the control box mounted in this casing there was no vibration of the control box but the generator shook like crazy. Tomorrow I will have new pins from Onan and a pin extraction tool from Grainger to reset new pins in the cannon plug. I will post pictures of the completed project in the next couple days. Here are a few pictures of the casing, its mounting location and the broken wire. I also noticed that the wires for the circuit breakers and the start switch were extremely short so I made up some jumper or extenstions to ease in the replacement of these switches for future repairs. Before I reset the pins we will use a jumper to test the generator start function on that wire, if it works we'll replace a few more chaffed pins in the plug.

I want to add that the control box can be removed from the generator without removing the generator from the coach. You need to use ratcheting box-end wrenches it is a little difficult but it can be done.

[Rob Robinson]

John if you could tell us the specifics of the pins and extraction tool it might help others. I imagine there is more than one pin type and therefore more than one extraction tool but maybe BB used your Cannon plug in several years of birds.