Where is the crank shaft sensor located on a 94 Chevy astro van?

The crankshaft position sensor (CKP sensor) on a 1994 Chevy Astro van is located on the passenger side of the engine block, near the bottom of the engine, usually close to the crankshaft pulley.

However, the exact location can vary slightly depending on the engine (4.3L V6 or other). It's generally a relatively small sensor with a single wire connector. You'll likely need to get underneath the van for the best view and access. A repair manual specific to your Astro's year and engine will provide the most precise location and helpful diagrams.