To find it definitively, you'll need to:
1. Consult a repair manual: A Haynes or Chilton manual specific to your 1993 Dodge Caravan 3.0L will show you a diagram and the precise location. This is the most reliable method.
2. Look carefully near the oil filter: Use a flashlight and carefully inspect the area around the oil filter. The oil pressure switch is usually a relatively small, cylindrical component with one or two wires connected to it.
3. Trace the oil pressure gauge wire: Follow the wire from your oil pressure gauge in the dashboard. It should lead directly to the switch.
Important Safety Note: Always allow the engine to cool completely before working on it. Be careful not to burn yourself on hot engine components. If you're not comfortable performing this task yourself, take your vehicle to a qualified mechanic.