B6000 starter switch

[pcdreams]

anyone know of an exploded view of the inside of a kubota b6000 starter switch (66621-55130). It seems my electrical problems lie in the switch. It seems like the contacts inside are likely dirty because I've cleaned hte outside connections and it's still having the issue. You might turn it 5-6 times and get nothing, then it might crank once then nothing for another 5-6 turns of the switch. I've cleaned/checked continuity through the rest of the system and everything looks test OK.

Ideally I'd just get a new one but, money and discontinued parts

 

[scdeerslayer]

Check it with a mulitmeter first.

Could be a relay also.

 

[Tooljunkie]

My L1501 had a start issue too, it would occasionally start,but cranked every time if i jumped it at starter. I found a bad wire in clutch circuit. Its been 100% ever since.

 

[Dave_eng]

Post a photo of the item you suspect being the problem so we are all certain we are taking about the same thing.

Do you have a multimeter?

Do you have a test light?

Without one of these two tools, which can cost less than $10 each, troubleshooting electrical problems is not easy.

Dave M7040

 

[pcdreams]

I do have a multimeter and have checked the lines from switch on down to starter etc for continuity, but I'm not sure how to check the switch. It has 4 wires total. 2 that run to the glow plug controller, the center one that goes to the switch and the other small wire that runs down to the starter.

https://www.dropbox.com/s/vshwsof8mbftiz7/b6000Electrical.pdf?dl=0

 

[pcdreams]

https://www.dropbox.com/s/ysn8amiz5v5al7y/starterswitch.jpg?dl=0

here's a pic of the switch

 

[Mike9]

You could pull the switch and shoot it with Deoxit and work it back and forth to clean the contacts. Worked for my Cub.

 

[Dave_eng]

The wiring diagram has on it a table or box that shows the internal connections in each switch:

The Title is "Circuit Diagram of Each Switch"
Main Switch
Starting switch
Light switch

I am going to provide the simple explanation first hoping, as you have the original wiring diagram, it will be easier to read than the one in your post.

Does this help you understand the info in the wiring diagram. Your mulltimeter should show continuity between the various terminals. Test with the wires removed from the terminals. I may have the terminal numbers wrong because I cannot make out the numbers b ut I will be close so a 17 might appear to me as a 19.

What is shown is that in one position the starting switch is providing power to the glow plugs. In the other position, the glow plugs are heating plus the starter is engaged.

Dave M7040

 

[pcdreams]

Thank you, Dave. That does make it clear. I was trying to figure out how to read those charts the other day

I'll check it out tomorrow and share what I find.

It would seem to be rather simple to replace the switch with maybe 2 switches if I must.

 

[Dave_eng]

If you need to replace the starting switch you could do it with two push button switches. One push button to power the glow plugs and the second to power the glow plugs and fire the starter.

Push button switches so you dont leave anything turned on.

Dave M7040

 

[scdeerslayer]

Push button switches so you dont leave anything turned on.

As long as they are momentary-on switches! Doesn't matter much what type of switch as long as it's momentary.

 

[pcdreams]

Well I checked it out but I'm not sure what to make of it. Sometimes it reads like it should (1 if open 0 if closed) other times it reads .3xx when the switch is off and 000 when it's closed. So I'm guessing maybe it's just dirty, but it doesn't crank or juice the glow plugs.

from what I see in the diagram, there are no relays but there is a rectifier (I read about what that is, but know nothing else about it), but I don't think that's part of the starting circuit so far as I can tell.

 

[Dave_eng]

pcdreams

If you are getting erratic readings during your multimeter tests, the switch may be the problem. It is wise to use test leads with an alligator clip on them so that the connection to the switch terminal is more positive. Test leads ends pushed against the terminals can result in erratic readings.

Alternatively, you can buy test leads at what was once Radio Shack. There will be a number of test leads about 12" long with an alligator clip on each end. Connect one end to the switch terminal and the other to the multimeter lead.

If the switch is removed from the dash for better testing access that helps.

There are no relays on your tractor so the switch is looking after larger current flows which can break the switch contacts down over time.

If you connect the wires back to the switch and have someone on the tractor activate the switch to the start position and hold it there, if the engine is not cranking, check for 12 volts on the small terminal on the starter solenoid.

You have already said that when you jump the starter solenoid wiring the engine cranks.

If there is NO 12 volts at the solenoid when the start switch is held on, I think that tells you the switch is done.

The rectifier is only involved in charging the battery and does not have any part in your failure to crank problem.

If you want to test the wire between the starter solenoid and the start switch, apply power to the switch terminal #53 rather than jumping the starter at the starter. the starter should engage like when you jump it at the starter.

Dave M7040

 

[pcdreams]

Yep I pulled the switch. Already had the fuel tank out so it was easy.

I stuck the switch back in and am reading 12 volts at the small wire on the solenoid but no crank.

I've actually not tried jumping to the starter. I just ran a continuity test. More than willing to try it though. How do I do it? I do know to have it out of gear for all this

 

[Dave_eng]

Below is an image of the starter solenoid which is part of the starter.

Just to be certain you know, this style of solenoid is like a big electrical switch with an additional mechanism to pull the starter gear into contact with the flywheel ring gear.

When a small amount of amps at 12 volts is connected to the small blade style terminal on the starter, the coil in the solenoid pulls a heavy brass plate across the two large terminals thus providing power directly to the starter motor. So you use a small amp flow to switch on a large amp flow.

The starter solenoid is partially like a relay but has the additional feature of pulling the ring gear into contact with the flywheel.

I looked back through the posts and now realize I was mistaken in thinking you had jumped your starter.

With the jumping process in the image, we will find out if your starter is good or not.

Before you do the starter jumping, can you check for 12 volts on the glow plugs when the key is turned.

Knowing the tractor must be out of gear is a big step. Many people jump their starter and the tractor is off through the back of their garage or into another vehicle.

Dave M7040

 

[pcdreams]

Will check glow plugs tomorrow. I'm done for the day it's mid 90's and high humidity. hehe

 

[rjcorazza]

I generally fix things correctly, but on my (2) zd mowers I wired up a relay to activate the starter solenoid. The added relay will activate at lower voltage than the starter solenoid when starting becomes intermittent because of resistance in wiring or connections.
There is no penalty in this method other than the additional electronic component failure potential. Use a 20-30a automotive relay, a fuse, and a couple feet of 14ga wire. There are instructions all over the internet on the setup.

 

[Dave_eng]

Will check glow plugs tomorrow. I'm done for the day it's mid 90's and high humidity. hehe

pcdreams

I was sitting looking at your wiring diagram again and was reminded of Kubota's power practices for the lights on your machine if you have any still working.

If you do you will notice their brightness increases with engine speed.

On an ordinary vehicle a noticeable change in brightness with increasing rpm's often indicates a battery starting to get weak.

The alternator or dynamo has three power leads coming out of it. It is producing three phase alternating current at voltages which increase with engine rpm's.

On more modern vehicles, all three output leads are rectified to direct current and then every accessory such as lights, wipers, electric fuel pump are powered by the same circuits which charge the battery.

On the B6000 and similar small Kubota's, only one of the three output leads is rectified to 12 volt DC and charges the battery. The other two leads go directly to the headlight switch. So instead of the light bulbs having a power wire and a ground wire, they are being powered by two hot legs from the dynamo.

They are doing this because the rectifier only makes use of 1/2 of the output of the alternator when rectifying AC to direct current and the rest is turned into heat hence the cooling fins on the rectifier.

I have not looked deeper into this but the headlight bulbs may be different than the standard automotive bulb because the see a higher voltage. Set your multimeter to AC voltage and measure the two leads going to a light bulb and let me know what voltage you read.

Using new style LED lights will likely not work on the AC lighting circuit.

Dave M7040

 

[pcdreams]

OK I'm getting 11.75 at the plugs.

I tried to jump it. It took me a while to get it to do it and it only cranked once and briefly. Couldn't get it to do it a second time.

The lights have been gone from this one since before I got it. The wires are still there and the back of the light switch is a nightmare. I think the connections are soldered type.

 

[Dave_eng]

pcdreams

Here are the facts as I see them.

Your switch is sending power to the glow plugs.
You measured 12 volts at the starter solenoid when the key was turned.

The starter does not jump start reliably.

If you think you are not getting a good job with the screw driver method, remove the small wire from the solenoid and make a short piece of reasonably heavy automotive wire with a slide on terminal on the end of it.

Bare the other end of the wire. Slide the slip-on terminal unto the starter solenoid.

File or scrape a small area of the battery cable so that you can make a good connection with your bare wire and then try jumping the starter using this wire. The starter should turn over every time.

You need to eliminate the obvious which is the cleanliness of each end of each battery cable. The end which attaches the ground or negative wire to the tractor frame or engine block is often overlooked.

After you have done this and the starter does not jump reliably, I think it is time for a starter.

Ebay seems to have some at good prices. The cheapest are probably made in China but that has not deterred me and I have had good luck with them.

I guess when you started you thread, you were focused on the switch and I should have asked you more about the symptoms first.

Please post some photos of your battery top and cables.

Dave M7040