The oil pressure sensor switch is located on the passenger end of the engine, just beneath and to the right of the thermostat housing. The easiest way to access it is to remove the battery and the plastic heat shield for the battery, if your car still has it. It's a round cylinder with an electrical connection on top.
Be very careful when removing it. Use an adjustable wrench to hold the square fitting that the sensor screws into. Then, using a 9/16 inch wrench, loosen the sending unit. Same thing when reinstalling the sensor.
If you think you have a bad sending unit, if you can wait until the middle of the week, I can loan you a mechanical gauge to check the true pressure. All too often the new sending units are also inaccurate. It's best to get a reading with a mechanical gauge, so you can compare the new electric sending unit's output.
I've taken a couple of pictures. I'll email them to you.
