Added oil pressure gauge no idiot light doesn’t work.

anyone run into this? I added an aftermarket oil pressure gauge and installed with a 1 1/2” brass pipe and a T fitting as the instructions suggested and that way I can still use my stock Idiot light. Installed everything, started it and no leaks! But noticed the idiot light didn’t turn on with Key on/engine off. Checked the wire and connections and all is good. Unsure what would cause it. Could it possibly be Teflon tape causing it to not ground. Never had that happen but maybe it could? Headed to a Christmas party so had to stop but wanted to hear your opinions. I also was wondering what your oil pressures run. I have a 360 that the guy had built at a race shop. Cold idle around 90 and warm around 75psi. Assuming they added an hi-po pump. Let me know what your thoughts are.

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