Opinions About The Instrument Cluster Diagnostic

[Suek]

Well as I said in another post I had a sender and fuel pumped replaced. When it gets to empty no low fuel light until it's in the middle of it. Was thinking about moving the needle as soon as the light comes on. I did the instrument cluster diagnostic test and read the fuel one. I have done this a dozen times and got different readings. Like 10.8, 4,or 7, etc. Now in my factory manual it says something about a short if I understand right from 0-20. Am I right? Maybe a bad ground since I've read it so many times online. I don't know if the test is that reliable. I already read the oil one isn't really that says everyone needs a part for the oil pressure.