Another glow plug question..

[brain55]

Short to open is an oxymoron.

https://en.m.wikipedia.org/wiki/Short_circuit

Yeah I know :-(

 

[dbotos]

In the short circuit, the wire would probably melt / smoke and the battery could get hot from rapid discharge and possibly explode.

 

[Coyote machine]

Thanks guys. I'll check them out individually.
If I understand correctly, a glow plug that is shorted out is open, like a bad light bulb. If the wiring is shorted out, it could be closed like a bare wire touching a ground, or open like a broken wire.
??

I think you're overthinking the problem. The glow plugs are either not working ~ open, (broken), or they are working properly, as in NOT open/broken, etc.
When the glow plugs are working properly the resistance they produce to the current flowing to/through them generates HEAT, and this results in the precombustion chamber of your tractor's individual cylinders getting hot and assisting in starting in colder weather.
When the glow plugs are not functioning, less heat is generated, and it is harder to start the tractor. Diesels are compression ignition (CI), unlike a gas engine where spark, (SI) gets the fuel to ignite.

If you have smoking wires, or other items causing smoking under your dash, that issue needs to be fixed too. As suggested you may have been burning a glow plug relay's contacts or some other circuit protection device. Either way, it needs to be investigated and solved.

 

[Jerry/MT]

If the glow plug is shorted out the meter will indicate infinite resistance(open circuit) not zero.

Poor choice of words on my part. As pointed out, an open circuit is not a short. Sorry for the confusion