TC25 Safety Switches?

[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.