I have a 7.5 onan generator model hdjak went out and started it up to let it charge house batteries, it started fine and ran heard a strange noise so I shut off and the starter was still cranking had to kill the batteries to get to quit.
now when I turn batteries on it starts cranking on its own, so I shut bat. off went to starter on gen disconnected the small soleniod wire turn batteries back on its fine no more cranking so I know problem is not solenoid or starter.
Looking for any ideas or some else that may of had this problem.
sounds like starter drive might be stuck in(staying engaged with the flywheel, if you can see it and try and pry it out of engagement, install your wire and try again.
I can not find an HDJAK
But there is an HDKAJ and it is a 7500 watt Diesel inverter.
I have one here now that I just did some work on....
I have not seen this problem myself...
I agree it could be a stuck starter and that was the noise you heard. With the small wire disconnected it kind of rules that out........but it
is worth checking into
I would check the rocker switch(s)....Disconnect the remote connector if it has one for a remote start switch.
If the rocker switches are ok and the remote wiring is not the problem I would make a guess that it has a starter relay.....a Bosch type relay that might be the problem...
After that it could be the ECU itself that is sending a signal to the relay to crank the engine.....The "brains" of the unit.....Potted PC board......
I have ruled starter out starter does not crank
with small wire that send 12v to solenoid disconnected it has constant 12v on it. I have also disconnect the remote start wiring it still has 12v on that wire.
SCDIV1 is there a separate relays like ice cube bosch under cowling that control that circuit
I took a look in the Service and parts manuals for you.
This machine has no relays...I was thinking of a 10 or 12 fixed speed unit....they have 3 relays....
The controller is integrated with the inverter section.....and that is not good...
Basically if you have no wiring issue between the rocker switch and the plug that goes into the inverter section.....there is only one solution....replace the inverter/controller.
These units are known for doing odd things like this and there is no separate part to repair or replace. The inverter section is one sealed unit and not serviceable. Onan used to sell rebuilt units but they no longer do....new only.
Just to verify the rocker switch wiring down to the inverter would require the top cover to come off. I have never found anything wrong with a machine for something like that.
I cannot copy and paste the troubleshooting page for you that says "generator cranks on it's own without pushing the rocker switch".....but it lists only the switch and or it's wiring down to the control or the control itself....I can give you the pinouts and the connector positions......You can just trace the wires from the switch down and verify it is NOT showing any closure on the pair for starting.
I have had machines that were dead and did nothing, one that labored so bad during cranking it would not start and burnt up battery cables.......and other odd behaviors and it was the inverter section everytime.....
The part cost alone is around $1500 Cummins-Onan part number is 300-6058-02
Fits HDKAJ models with Spec Letter A thru K
Sorry for the bad news...
Another problem that I have seen is the magnets can come apart on the rotor and it makes a mess.....
You did say you heard a noise! That is generally not likely though and usually a catastrophic failure....This message has been edited. Last edited by: SCDIV1,
SCDIV1 thanks for info don't sound good
I have had the gen running its for sure starter cranking, here's what I did with wire disconnected from starter had my boy hold the switch to start position I touch the solenoid wire to solenoid unit started right up and I pulled wire back off to keep it from cranking and I ran it for 2-3 hours ran fine.
Is the control board 1500 by itself and would have the part number?
Thanks for the help
It's not just a control board...
The inverter section is a sealed unit and the control is inside. The complete unit gets replaced and is NON serviceable. They have never offered any info on doing it any other way.
It is really not all that difficult a job to replace it....I have done quite a few...
I don't know why they stopped selling the rebuilt units.....they were about half the price....
I just installed a control board in a 10KW diesel. That is not an inverter and the board alone is over $600 from Cummmins....
As they say in some pats of the country....
Cummins is mighty proud of their parts....
I think the noise you heard was the starter re-engaging after the engine was running.....
This is a very common problem in the automatic generator world....We call it failure to crank disconnect.....and it destroys a lot of starters and flywheels....
My Duramax diesel in my pickup has a starter disconnect feature.....I am sure of it....Once the engine reaches a certain rpm the starter will not stay engaged even if I am holding the key down.....
My guess is there is a failure in your control relating to crank disconnect....
If in runs and works fine, except for the starter staying engaged why not just put a push button switch in the small wire to the starter?
FWIW, I just had a problem my MIG welder,it was mice making a new home & chewing on the insulation of the wiring.
It caused a short and after I repaired the damaged wires, it still has problems. It must have damaged the board since the gas solenoid is always energized regardless of the gun switch .
Just thought I would offer another scenario.
PS: Anyone have a good mouse repellant?
I have not found mice to be the problem in machines like this. I don't think they like the diesel smell as I have never found them in any diesel powered machine.
Mice do a lot of damage for sure in piles of equipment I see...
I think the adding a cranking interruption switch idea is a good way to avoid spending a lot of money. If it works normally other than the cranking issue.....do it...
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