Engine Stop Solenoid not working - L48

I posted back in January about this and I am still having problems. My L48 backhoe is now starting only occasionally. The problem has become worse over the last month, and now it almost never starts. I can clearly hear the stop solenoid click when it is working, and the motor starts right up. In the past, the motor would sometimes not start.....and there was no solenoid click.....and I'd let it sit 5 minutes and it would start and run all day. Now, if it starts, it may run for a couple of hours or it may die right in the middle of going up the driveway. And then, it will not start no matter how long I let it sit. A few days ago, I bought a new stop solenoid and installed it. I turned the key, heard the click, and it started right up. I turned it off 15 minutes later, and tried to restart it and there was no click and no start. 5 minutes later it clicked and started and ran the rest of the day, so I thought maybe I just had not turned the key all the way or something. Then the next day, it started right up, and I drove it 200 feet up my driveway and it died in the middle of the driveway. I had no way to move it and we could not go around it. I took the old solenoid, and sawed off the fuel stop rod, and took the new solenoid out and reinstalled the old one, and the motor started right up, so I know for certain that the solenoid is not actuating the stop rod. I now was able to move the machine. I was picking up debris along my driveway, so I kept the machine on the driveway and kept it running for several hours. I killed it by removing the air filters and blocking off the air intake with some folded up heavy-duty trash bags.

That's where I am now. I'm a rookie mechanic and electrical problems give me fits. I have the workshop manual, but I can't decipher everything in the schematic. In the manual, it says if the motor cranks but doesn't start, that the problem is the solenoid. Oh, and I also have a 1-year old key switch and I removed that and it looks brand new. Plus, all the electrical system works when the key switch is turned on. So, I'm guessing the key switch is still good.

So, I have a bunch of questions:

1. First, I want to get a clear answer to a question I have about information I see flying around a lot. QUESTON: If any of the safety switches is bad, my understanding is that the starter motor will not even crank, is that correct?

2. QUESTION: My starter motor always cranks, so does that mean that the safety switches have nothing to do with the function of the stop solenoid and I should not bother testing the safety switches?

3. QUESTION: Is there or is there not a relay that is connected to the stop solenoid? There is no mention of one in the service manual and I am too much of an idiot to tell if the schematic is showing a relay connected to the stop solenoid or not.

4. All the fuses are good and I have cleaned all the blades on the fuses with a brass brush. However, I unscrewed the fuse block and looked at the back, and there is some corrosion where one of the heavier gauge wires is attached to the back of the fuse block. I don't have a place indoors to store the machine, but I keep the cockpit and dashboard covered when I'm not using it. It would be good if I could replace the fuse block. QUESTION: Is there any way to clean the fuse block? Could I use baking soda like you can use on a battery terminal? QUESTION: How do you replace the fuse block? I can't figure out how you remove the wires from the back of the block. Are they soldered in place? QUESTION: Or, is the fuse block attached to the wiring harness, and you have to replace the whole harness?

5. On other forums, it's been suggested that it is a grounding problem. QUESTION: The rest of the electrical system works fine, and the starter motor cranks great, so I'm presuming it is not a battery grounding problem, is that correct? QUESTION: Exactly what would I be looking for if it is a ground problem? The solenoid itself is bolted to the engine, so that can't be it. Where would there be another ground that would be affecting the solenoid?

Any help would be greatly appreciated!

Thanks to both you guys.....very helpful. I’m determined to learn how to diagnose this problem. I’ve watched some videos on YouTube today on how to track down circuit problems in cars and got some good info from them. A key to not flying blind was being able to decipher the schematic (pretty obvious). If I posted a scan of the schematic, could Wolfman tell me if there is a relay between the key switch and the stop solenoid?


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Attached are the 3 pages of the electrical schematic for my Kubota L48. They are at the highest resolution that I was able to set and still have them not be larger than the allowable file size for uploading. If you need more detail of any part, let me know and I will zoom and scan that particular part of the schematic. I really appreciate everyone''s help.

North Idaho Wolfman said:

Just off of the schematic that Steve A. posted (Thank you!) there is nothing in line with the stop solenoid, just the key switch and the 10 amp fuse.

But.... I'm worried as there are 2 different model variations of the L48's and the second variation has another controller in it for an added seat switch, I don't know how that controller works in this case, maybe not at all, but it could play a role.

Click to expand...

I bought the machine used from a rental company and I discovered that they bypassed the seat safety switch. Attached are photos of the switch and the bypass they did that I have not hooked back up. Just thinking about it now as I took these pictures, the ends of the terminals used for the bypass are exposed and just lying on the deck that the seat attaches to. If part of those metal terminals are touching the chassis, could that possibly be the problem? But if they were touching, the chassis, wouldn't that cause a short and blow a fuse? (that is not happening....the fuses are all good). The machine is a 2004 model year.

I bought the machine used from a rental company and I discovered that they bypassed the seat safety switch. Attached are photos of the switch and the bypass they did that I have not hooked back up.

Just thinking about it now as I took these pictures, the ends of the terminals used for the bypass are exposed and just lying on the steel deck that the seat frame attaches to. If part of those metal terminals are touching the chassis, could that possibly be the problem? But if they were touching, the chassis, wouldn't that cause a short and blow a fuse? (that is not happening....the fuses are all good). The machine is a 2004 model year.

That's great! Thanks so much. I will give that a shot and report back on the adventure.

Wolfman, thank you too for all that information. I have emailed Kubota to see if I can get the correct schematic. Meanwhile, attached are images of the back cover of my manual (and it has a print date of 2000, so that would indeed be an old version) and an image of my serial number. Also, I went onto Messicks and downloaded the wiring diagrams for "old type" and "new type", just as you said there were. I'm going to try to go through the wiring harness using those diagrams to at least make sure that my connections are tight. I bought some DeOxit D5 contact cleaner to clean my fuse block and all connections that I mess with. I have a Power Probe III circuit tester and a Power Probe ECT3000 short circuit detector coming that should be here Monday, and I'll start trying to find the problem. I appreciate yours and everyone else's help.

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