Solenoid clicks

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cgmartin

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Jan 3, 2014
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Hello folks, I need a second opinion ref my Onan 4000 KWK gas generator. I posted on another Forum, and some suggestions included a blown fuse. I am too stubborn and believe there is another cause. Here's the problem: I replaced my old fuel pump and relocated it outside of the generator housing ( a separate story). I accidentally let the pump's hot wire touch a metal surface while I was cranking the generator. At the time, the generator would crank but would not start. Afterwards, it would not crank and the solenoid would only click. (house batteries are 100% charged-guaranteed). I can feel the solenoid with my hand when it clicks, so something is indeed clicking inside. Did the solenoid lose its power? Did I fry it? Did this stupid act on my part fry the solenoid? Is that even possible? I know nothing about testing the solenoid. I have the solenoid out. Is there a bench test with a multi-meter I can do? Or should I plan on replacing the solenoid?  thanks
 
What Ernie said. Or just check the output terminal on the solenoid for +12v when it is engaged (after the click).

I've not seen a fuse between the solenoid and the starter motor, so I think you can rule that out. I suppose there could be one between the 12v source (battery) and the solenoid input terminal, though.

Maybe I'm assuming know how a solenoid works.  There are two power inputs, one that drives the solenoid itself and makes it click, and another for the power that it switches (the power to the starter motor in this case). You can have power on one but not the other, or the solenoid can "click" but fail to close the actual switch for the power to the starter.
 
Thanks for your responses. Just to cement my understanding...can you confirm this for me?

1. Ernie, when you say to bypass the solenoid, do I place the jumper cable on the red cable from the solenoid that appears to go to the generator starter?

2. Gary- When you say to test for +12 volt on the output terminal...is this the same terminal as the one where I attach the jumper cable?  There are two red cables on the solenoid, one from the battery and the second, which if I understand it correctly, is the output terminal to which I attach the jumper cable, correct?

Thx.
 
There should be 4 wires on the solenoid. The smaller two are the wires from starter switch (hot & ground) and the larger two come from the battery and go out to the starter.  Since the solenoid clicks, you know the smaller two wires are working OK, but maybe the internal connection for the larger two is not. You can either measure voltage on the larger two, or simply jumper across them (which is essentially what the solenoid does internally). The wire from the battery should have +12 (or more) at all times, while the one to the starter (the output side) should have +12 when the solenoid "clicks" closed. Measure voltage from the terminal to any convenient battery ground point.

Note: some solenoids rely on the mounting bolts for a ground and only have 3 wires, one for the starter switch and the other two the in & out to the genset starter.
 
Since I already had the solenoid out, I thought I would bench test it. I applied 12 volt dc power to the + side of the small terminal. I did not get a click. A test light and a multi meter verified I had 12 dc volts going to it. I then checked what is supposed to be the - small post, and also got a reading of 12 volt dc power. A continuity test with my multi meter indicates continuity between the two (+ and -) small posts.  If one is the ground and one is a positive, why would there be continuity? There was no clicking at any time and no power at either of the large terminals. I understood that once 12 volts were applied to the + small post, that it would energize the magnetic coil inside, and cause a plunger to rise and make contact with the two large posts, and send power across from the battery side to the starter.  I did the same test with a brand new solenoid I bought today (Onan part 0307-2586), and I got the same results. Did I do an accurate test?
 
You need to have a complete path from the power source and back to make a complete circuit. You applied 12(+) on the one small terminal, but the other small terminal must have a path back to 12(-).

Look here:

http://www.12voltplanet.co.uk/electrical-circuit-basics.html

Once you have a complete circuit from power source to and back, the coil in the solenoid should pull the contacts connected to the larger posts together. You should read (0) ohms across the contacts with the solenoid coil energized. That does not always mean the contacts are good. You can read (0) ohms, but the contacts can be in less than optimal shape and not pass enough current to carry the load of a starter.
 
Sir, you are a genius!!  That was a very informative web page you had me look at. I did as you instructed, and voila, my solenoid does indeed click. That information was not in any of the numerous self-help videos I saw on YouTube, which had me chasing my tail. I was afraid I might get a spark at first because of the continuity between the + and - of the two little connectors, which I understood as both being connected, but that was not the case. I learned something new and I owe you a debt of gratitude.
 
Glad to be of help, and you owe me nothing. I've already been prepaid by the information and lessons I've learned here.
 
cgmartin said:
Sir, you are a genius!!  That was a very informative web page you had me look at. I did as you instructed, and voila, my solenoid does indeed click. That information was not in any of the numerous self-help videos I saw on YouTube, which had me chasing my tail. I was afraid I might get a spark at first because of the continuity between the + and - of the two little connectors, which I understood as both being connected, but that was not the case. I learned something new and I owe you a debt of gratitude.
You have continuity because you are measuring the resistance on a coil of wire. O continuity the coil would be open, thus it wouldn't work. If you would have had say .01 ohms resistance then the coil of wire would be shorted and would have blown the fuse.

Have you found the problem?
 
Yes. After all this, I found that my somewhat new Trojan T-105 batteries, with 12.9 volts, were insufficient to crank the generator. Thye were showing as being 3/4 on my panel. I will be installing a disconnect switch to prevent them from draining. But what surprised me, was that even with the engine running and activating the front switch, to tie the engine and house batteries, the generator would not crank. I think that with a full load, everything will be back to normal.
 
I have been following this very interesting thread through 11 posts.  I have to ask: Does anyone know what kind of RV cgmartin has?  Thanks.
 
So just where are you showing 12.9 volts? At the batteries or at the wire on the solenoid?  If you have 12.9 volts at the solenoid and it won't crank over, measure the voltage on the wire going to the solenoid while you are trying to start it. If the voltage drops when you try to start it you have a bad connection. 12.9 volts should crank that generator with ease, the starter is only rated at 12 volts.
 
youracman, I have a 2008 Tioga 31M.  It has the Onan KYK 4000 generator.  I bought it used from El Monte Rents about two and a half years ago. It has 112,000 miles.

charlie 5320, I used my multi meter to measure volts at the + battery terminal of the house battery. (I have two Trojan T-105 batteries). My motorhome uses the house batteries to start the generator. It measured 12.9 volts.

I then measured volts at the large solenoid terminal where the + cable from the house battery is attached. It also measured 12.9 volts.

I then used the multi meter to measure volts at the large solenoid terminal that goes to the starter. While cranking the generator, the volts went down to 6.4

I cleaned all wire connections with a piece of Emery cloth, and also ensured all connections were tight. I can't account for the drop in voltage between when the coil in the solenoid is energized and sends voltage to the starter terminal. Like I said previously, this is a brand new Onan solenoid, so I doubt there is a problem with it.

By now, my fingers are sore and cut up from doing all this work in the confined space where the solenoid goes. It has been a learning experience, but taxing, physically and mentally at the same time.  Thanks to you and all the others for their patience and input and for my volume of issues and questions.  Mea Culpa!!
 
OK with that voltage drop you have either a bad connection at the battery or a bad cable. You should have very little voltage drop. It takes a full 12 volts for your starter to work. Take the ground off the generator case and the frame where it attaches to and clean them.
 
cg- at post #12, I note that Charlie suggested you measure the voltage at the solenoid terminal that connects the house battery TO the solenoid while hitting the Onan start button.  I don't see where you did that; but I see where you did measure the voltage at the solenoid terminal going from the solenoid to the Onan starter and observed a huge voltage drop.  If you take the measurement Charlie suggested and it also drops significantly from the 12.9 volts (no load) reading then you have essentially proved the new solenoid is not the problem (and that is highly likely what you will find to be the case.)

I believe Charlie is "all over" your problem; i.e., "....you have either a bad connection at the battery or a bad cable." 

Once you find that the input power lead to the solenoid also shows a huge voltage drop (above test) there is one more easy test you can do (with a helper) to verify that you most likely have a bad connection at the battery or a bad cable, but you will need a helper.  On the  house  battery bank itself, measure the voltage when you hit the Onan start button.  Measure it across the actual battery posts (+ and -) .... not the battery connector.  If that voltage does not drop it is almost a certainty that  "....you have either a bad connection at the battery or a bad cable."

In reading RV forums over the years, it is amazing how many problems involving 12v systems are corrected by cleaning/tightening terminals and ground connections.  You have already done that at the generator...........it's probably time to move the the battery(s).

Good luck with the fix, and thanks for keeping us all posted.

 
Well, I am back to report the latest on this saga. I had a mobile rv mechanic take a look at my generator.  After he told me what the problem was, I had to get up off the floor to regain my composure (my heart pill helped). The fly wheel is frozen. It will not move. He said that this may account for the drop in voltage on the starter side of the solenoid, because it was forcing itself to gain voltage to engage the starter. I also stuck my hand inside the shroud and could not move the fly wheel. He said it could also be the starter itself, but he will not know until he removes the generator.  Not good news. I anticipate the cost to be between $500 to $1,000, if I'm lucky. Has this ever happened to anyone else?  Just in case some are wondering, this generator was always properly maintained, with sufficient oil, and exercised at least twice a week.  It just went from being trouble free for two years, to being frozen the next minute.
 
I doubt you could turn the flywheel by hand. I used to use a long screwdriver to pry them around. That said a frozen starter is a reasonable possibility as is a seized piston. In any event, if it can't be turned, you do need to pull the motor. On reflection the generator may also be on that list depending on how its driven.

On further reflection the starter may been seen to be engaged if  you have access to look.

Ernie
 
I just saw a couple of posts in this forum where the fly wheel seized up and they were able to free it by hand, and in some cases the seizure was caused because of low voltage to the starter, then the starter's impaller jammed against the fly wheel, causing it to seize. In my case, the generator will need to come off, unfortunately. It sounds that like if nothing is broken, my mechanic might be also to break it loose, and it might not cost me a bundle, or maybe just a starter, so I am keeping my fingers crossed.
 
Hello, I am back to report on this saga. I removed the generator. Removed the starter motor. I was able to move the flywheel by hand. I felt a slight pressure, indicating that the pistons were free to move up and down. That is good. I took the starter home to bench test it. I applied 12 dc power to the large terminal, and also grounded the starter at different ground points. Nothing happened. A sticker on the starter says it is a positive ground, but I don't know what that means. Did I do the test correctly? If so, do I need a new starter? It is part no,. 191-2351.
 
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