To be certain:
* Consult a repair manual: A Haynes or Chilton manual specific to your year, make, model, and engine will show you a diagram with the exact location. This is the most reliable method.
* Look near the oil filter: The switch is usually a small, cylindrical component with one or two wires attached. It's often close to, or even slightly behind, the oil filter.
* Use a flashlight and mirror: The area can be cramped, so a flashlight and a mirror might be necessary to get a good view.
Caution: Be careful when working around hot engine components. Let the engine cool completely before attempting any inspection or replacement.