Oil pressure warning light

I would like to check the following issue with you as I have a jaguar xe 2.0 l Gtdi engine and i had the issue that the oil pressure warning light does not illuminate: when disconnecting the oil pressure switch located at the oil filter housing or when shorting the connector to Ground. I went an tested another car with tge same result. The voltage supply is 1.25 volts at the oil connector pressure switch ( both vehicles same). The voltage supply comes from Body control module. Can any when check how the oil warning light can be illuminated.