Electrical problem
1999 Cadillac Catera 6 cyl Two Wheel Drive Automatic

i have a 99 cadillac catera i put a new fuel pump in it & i put a new fuel pump relay in it and i have checked the fuses and they are all good but i still have no power going to the fuel pump i found on the net that it might be in the oil pressure switch but i dont know how to check it unless its with a volt meter but i dont know how many ohms its suppose to show any idea what the problem is with the power to the pump