You are dealing with a bad crankshaft sensor if the reading is zero. Depending on the vehicle model, the ohm value should be between 200Ω to 2000Ω. For instance, Ford Escape 2008 model's crankshaft sensors have a range of 250Ω to 1000Ω internal resistance. So, referring to the vehicle's repair manual is wise before jumping to conclusions. (1)