Open the hood and look at the oil filter housing on the front of the engine above the starter. The oil pressure switch is there on the lower section of the housing. You need the special socket to remove it and be careful tightening it as it is a taper thread and going too far can damage the engine block.
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.