Base on that logic, I guess I would disconnect the switch check for continuity and have someone start the engine. See "if" the switch is actually closing. 'Might want to also re-check the part number of the new switch-sender and see if it's the correct one they sold you.The "oil pressure gauge" in your '05 is nothing more than an idiot light. The "sending unit" is a switch that closes at something like 5 psi. When computer sees the switch close, it moves the needle to mid-scale.