TC25 Safety Switches?

[TORQUIN]

I have a TC25 I am working on for a buddy. My tractor is a Kubota, so I am not familiar with this tractor. He started it and got it off the trailer, but by the time he got it to the garage a wire had broken on a safety switch, for range, and it would no longer turn over. Wire broke right where it goes into the switch body. I found that the switch in question costs over 100 bucks so, for now, I bypassed it by connecting the wires for it together. Engine still will not turn over, so I am looking for the rest of the safety switches. I know about the PTO switch, but are there any others, such as on the gear box, clutch, brake, etc.?
I have checked and found all fuses along the right side of the firewall are OK. I do not know if there are fuses anywhere else besides the one beside the starter, in the harness.

Thanks,
Chris

 

[Hughman]

On my TC which is a hst model, there are switches to make sure the gear is in neutral, brake is set, PTO is off and your butt is in the seat. Seat switch is easy enough to defeat with a jumper.

 

[TORQUIN]

Forgot to mention, this machine does not have shuttle shift, and is a geared machine with 3 ranges.
I looked for the seat switch, but have not seen any wires going to the seat. When trying to start it, I did sit in the seat in case there is a switch in there. I will continue to look for the seat switch.

Thanks,
Chris

 

[WM75Guy]

If the TC25 is like my TC40DA, the safety switch system turns off the fuel solenoid so the tractor will still turn over, just not start. If it won't turn over, your problem may be elsewhere, like the ignition switch or a fuse.

 

[ruffdog]

Behind LR wheel....mid pto switch, gear range switch, rear pto switch.

 

[TORQUIN]

I am not getting power to the switches on the left side. I'm guessing that the mid PTO switch is the one factory bypassed, since I don't have one of those. Mid-PTO seems to be the last one in the line, since it goes straight to ground from the connector. Haven't pulled the harness sheath apart to find out which is the first one in the line yet. Trying to avoid that, if possible. All fuses one right side of firewall have been checked again, and are fine.
Starts and runs fine if I bypass the starter circuit with a remote starter switch, so the fuel solenoid is working fine.
Anyone got a wiring diagram?

Thanks,
Chris

 

[kydick]

cant remember too much about it now but several years ago my 3930 would not start. there was a diode behind the instrument panel that had to be replaced

 

[thclimer]

I hope these help.

 

[TORQUIN]

I hope these help.

Interesting. I do not have an accessory position in the ignition switch of this tractor. Also,I have to assume that the "Glow Plug Heat" position, 3, is also the run position, for the switch.

Thanks so much for the diagrams. They confirm what I am seeing on the tractor, no glow plug timer, but make me wonder about the actual operational details of the glow plugs (another issue I am working on).

Thanks,
Chris

 

[thclimer]

The OEM ignition switch on my TC33D was a pretty flimsy design and failed. I replaced it with a more robust one from NAPA. I wonder if yours was replaced at some time?

TC33D Glow Plug Problem Fixed

There also could be some variation withing the TC25 series so the schematic which supplied might not be 100% accurate. How many wires do you have connecting to your switch?

 

[ruffdog]

Interesting. I do not have an accessory position in the ignition switch of this tractor. Also,I have to assume that the "Glow Plug Heat" position, 3, is also the run position, for the switch.

Thanks so much for the diagrams. They confirm what I am seeing on the tractor, no glow plug timer, but make me wonder about the actual operational details of the glow plugs (another issue I am working on).

Thanks,
Chris

With my TC33D, the glow plug "position" of the start switch was not a position with a detent. It was the area between run and start. When the glow plug light comes on I would stop turning the key until the light went out, then continue turning to start. Looking at the wire schematic provided above, I see the safety switches are on the grounded side of the safety relay. When all the switches are in the correct position, they provide the needed ground for the relay to work. Grounding that circuit at the relay would bypass the switches for testing.

 

[TORQUIN]

Four wires to the ignition switch.

Thanks,
Chris

 

[TORQUIN]

I have grounded the circuit already, at the PTO wire, which is first in line, per the schematic. That all seems good. Now back around the the start relay, which seems to have no power at all. Just purchased the service manual and am studying that for additional info.
The service manual implies that there should be another position, but it also makes a distinction in some areas of the wiring about an "economy" services of TC, which I am beginning to think I have, since this is a gearbox unit, not an HST.

Thanks,
Chris

 

[TORQUIN]

It's looking like the ignition switch is bad. When you go to start positions, one of two terminals that are supposed to be hot, are not. The one that's not is the purple wire going to the start relay. I jumped the dead terminal on the back of the ignition switch and the tractor started right up.
The problem now is the weird series of diodes that appear to feed back into the circuit so as to power the glow plugs, but on this tractor it is exactly opposite, in that the glow plug circuit is getting power directly from the switch but the purple wire may get power when fed back through a diode. It's quite confusing because some of the wire colors don't match either.
It's almost like this tractor was supposed to have a glow plug timer and they did some rigging the eliminate that and drive them directly from the ignition switch.

Thanks,
Chris

 

[thclimer]

Sure sounds like someone did some modifying there.

 

[Mtsoxfan]

My TC29D had a main fuse, left hand side under hood, that popped once. This was a no start issue for me. Pretty easy to spot. It is just 2 wires (hanging) going to a fuse.

 

[Geunther]

I have the TC33. Geared, not HST. There is a safety switch on the range and one on the clutch. I have not noticed there being one on the rear PTO, or the brake. I replaced the starter and switch a couple years ago, as both failed within a few weeks of each other. I finally gave up on the glow plugs, and put a block heater on the engine (rear freeze plug on block). I have had no issues starting below about 45 degrees, if I plug in the heater. It takes about 45 min to bring the block up to a starting temperature. Yes, working glow plugs would be better, but I don't use the machine enough in the winter to warrant the expense of that repair. I have the same main fuse on the left side the Mtsoxfan has on his TC29D. You will have no problem finding it.