To find it, you'll need to:
1. Identify your engine: Look for an engine code (usually stamped on a metal plate on the engine block) or check your vehicle's paperwork. Knowing the engine (e.g., 3.9L V6, 5.2L V8, 5.9L V8) is crucial.
2. Consult a repair manual: Once you know the engine, obtain a repair manual specific to your 1991 Dodge Ram Van and that engine. These manuals will have diagrams showing the exact location of the crankshaft position sensor. A Haynes or Chilton manual would be a good place to start.
3. Online resources: Websites like AutoZone, Advance Auto Parts, or even YouTube may have videos or diagrams that show the sensor location for your specific engine. Search using your year, make, model, and engine code.
Without knowing the engine, it's impossible to give a precise location. The sensor is typically found near the crankshaft pulley, often on the engine block itself, but its exact placement can vary significantly between engines. Incorrectly attempting to locate and work on it without a proper understanding of your engine can be quite damaging.