Hi Need_another_tractor, welcome to the forum!
I believe you have a pressure switch just before the gauge?
It should look something like this:
The switch is needed because it cuts out the electrical charging when the engine is off, and during cranking/starting the engine. When the oil pressure is up, the switch closes and the alternator starts charging.
If you want to block the oil pressure line, you have to do that after the switch, otherwise you will not get the battery charged.
I believe you have a pressure switch just before the gauge?
It should look something like this:
The switch is needed because it cuts out the electrical charging when the engine is off, and during cranking/starting the engine. When the oil pressure is up, the switch closes and the alternator starts charging.
If you want to block the oil pressure line, you have to do that after the switch, otherwise you will not get the battery charged.