OEM Ignition Switch for ZD326 Worth the Extra $70+?

[Mr Haney]

I was tired, so I put off coming up with a new plan for putting safety switches back in the loop. It appears to be astonishingly easy. Someone tell me if I'm wrong.

The controller has a receptacle and plug. All the safety switches go into this connection, as does the RW wire that carries hot to the starter.

All the safety switches (arms, seat, PTO) I care about are NO, and I could convert the brake switch to NO just by installing a different switch (same part as the arms and PTO, already in my shop) that fits perfectly. This gives me a whole bunch of NO switches in series.

It should be simple to wire them in series with RW, right at the connection, with tiny jumpers or a modified plug. If I do that, if any one of them fails to close, no start. If this is correct, Kubota's decision to run all these switches through the $340 controller is more mysterious than ever.

The plug and receptacle look generic, so I guess I can buy whichever one, M or F, is right and rig it with jumpers.

I don't see any reason to include the brake switch, really. It would just serve to make the mower operate like it did from the factory.

The more I think about it, the more I like a choke cable on the shutdown lever instead of a circuit to control the solenoid. I believe it would make it impossible for the motor to ever refuse to shut down.

I still have not checked the controller ground. It would serve me right if it turned out to be the whole problem.

 

[Mr Haney]

I am too lazy to go out in the rain and look, but the connectors look like plain old molex.

 

[Hugo Habicht]

The brake switch has both contacts, NO and NC according to schematics. I still do not believe switch being open when brake applied.

And there is a bit more than just connecting all switches in series.

 

[Mr Haney]

I tested it with a meter when it was off the mower.

 

[Mr Haney]

"Normal close" in the manual means it's closed when it will not let the mower start. Normal is when you sit in a stubborn mower and curse at it.

 

[Hugo Habicht]

"Normal close" in the manual means it's closed when it will not let the mower start.

I do not think this is the way NO and NC contact descriptions on spring loaded switches work.

Have you actually checked the switches and contactors as I described before in post #12?

 

[Mr Haney]

I went through the schematic. I tested both types of parts on the bench. I removed and installed the brake switch twice. If I'm still wrong after all that work, wrong is okay with me.

 

[Mr Haney]

I looked at the shut-off lever.

To shut the mower down, you have to rotate the lever backward. That means that in order to activate it from the seat, you would need to connect it with a rigid rod, and this is a problem, because with mechanical things, pulling is usually simpler than pushing.

The silver lining is that the solenoid also has a lever, and it can be pulled toward the seat.

The easiest but least elegant option is to tie a string to the solenoid lever, put a knob on the end, and leave it next to the seat.

 

[Hugo Habicht]

I went through the schematic. I tested both types of parts on the bench.

Testing the switches on the bench in my humble opinion is not the way to locate the fault in your mower. Please read post #12 again.

But I wish you good luck getting the mower working again.

 

[Mr Haney]

You need to go back, read what I wrote all over again, look at the schematic, and find yourself a ZD326 to look at in person. I explained everything, but your replies don't take account of it.

But I wish you good luck getting the mower working again.

I got the mower running days ago, as I reported at the time. I turn the key, and it starts.

I'm at the point where I'm replying to the same theories repeatedly. I appreciate your help, but I don't want to repeat all this tomorrow. Maybe you can find yourself a mower, check it out, and come back with your own findings.

 

[Hugo Habicht]

Maybe you can find yourself a mower, check it out, and come back with your own findings.

I did that already a good while ago. And it is running now with all safety functions working, feedback in the dashboard (and via LEDs) why it won't start and emergency start procedure just with the key when switches are faulty.

Details you find here: G1900 repair

 

[Mr Haney]

I rescued a G1900 lawn tractor

 

[Mr Haney]

More fun today. The mower is fine the way it is, but I can't stop.

I replaced all the relays since it was cheap, just to be sure they were not the issue. I also found what appears to be the controller ground and cleaned it. I found something or other grounded to the voltage regulator, so I cleaned that ground, too.

The ground was attached to the forward screw that holds the regulator on, and there is some kind of mechanical rod blocking access to the head. I finally got it out with a universal. Putting it back in, it felt like I was cross-threading it, but it turns out that's just how that screw feels.

Tried to start the mower. Nothing. I was in for some sweaty work.

Jumped the starter relay. The idiot lights turned on. The starter went "ACK," and then everything went dark.

I'm standing there thinking, "I finally killed it." I couldn't even get the starter to fart by applying positive directly to the solenoid.

I went over everything again and used a battery tester. Then it occurred to me to finally check the horrible positive battery connection. I hate to use the Jeff Foxworthy slur, but this was a true redneck job. The owner somehow broke off the end of the cable, so he found a clamp-on connector for a much bigger cable. Instead of running the cable's end through the clamp, which was too big, he ran one of the clamp's screws through a hole in the ruins of the original connector and screwed it to the clamp. Rust everywhere. I couldn't believe it had passed enough juice to even make the fuel gauge work.

Took some of the parts to the pedestal buffer and cleaned them up. Reinstalled the RN clamp. Tractor would not start. But the idiot lights were on. Jumped the starter relay, and she fired right up.

There is almost nothing left except the controller that could be in need of replacement or patching. I guess I could take it out and blow off the pins with air to see if crud is shorting anything. It is indeed potted, as an earlier post says, just like a Dumble amp.

Reverse-engineering this thing would be a major triumph for owners everywhere. I guess if I really wanted to get cute, I could see what I can do with the Kubota schematic and an Arduino.

It appears you can put a control lever switch on the brake and then run all the safety switches off a single relay. After that, you just have to figure out the shutoff circuit, unless you're okay with shutting it down manually or installing a button.

I thought I could shut the engine off with a cord connected to what I believed was a shutdown lever. Turns out it's the throttle.

 

[GreensvilleJay]

1st issue the 'battery cables' . Both of those need to be replaced with nice,new molded ended ones. A LOT of 'electrical issues' magically disappear when the proper wiring is in place....

2nd ,the 'box'. Yes for about $20 you can buy a PIC (I never got into Ardunios...), some 78L05s, LEDs, relay and make a 'clone' of the 'controller'. probably 1/2 the cost will be the case ! Depending on the 'logic' might only need a few diodes and a relay ( $5). Actually it's the connectors and wires that cost real money.. the PIC ( or Ardunio) is less than a buck.

Now IF there was enough real interest in a 'clone', I might entertain doing the R&D.

 

[Mr Haney]

I found someone to design a cheap circuit to turn the mower off, and then I tried to use LTSpice to simulate it. Then I gave up trying to figure out LTSpice.

I would have thought a circuit design program would have a relay in it somewhere, but apparently you're supposed to design the relay yourself or use one designed by someone else. I downloaded one made by someone else, and I could not figure out where the pins were or anything. So I went and got a haircut.

The parts cost, literally, something like $2.00, and I'll bet I already have them, so I may try to breadboard it and see if it blows up.