what does the cranking sensor do

If you mean Crankshaft position Sensor....have a look here: http://easyautodiagnostics.com/misc-index/ckp-cmp-sensor-basics-1

Have you tested if you have spark and fuel? One or the other is faulty. Easy way...buy a can of starting fluid and spray a little (it does not take much! 2 seconds spray....) in the throttle body intake while a helper is cranking, if it runs for 5 seconds and dies its a fuel starvation problem. If it does not run, start looking for ignition problems

You mean the crankshaft sensor, see explanation below: If the crank sensor completely fails, the computer can no longer calculate engine speed. When this occurs, the ignition system and the fuel system shut down causing the engine to crank and not start or to stall if the engine is running. Read more : http://www.ehow.com/about_5860665_bad-crank-sensor-symptoms.html

apparently not fuel issue, sprayed starter fluid into throttle body, no start..So looks like i'll be checking crankshaft sensor, thank you all for your input.......great site.

Yep, that's the thing to check. If you have spark, the crankshaft position sensor is working. But Just because you have no spark, it MAY be the CKP.... or not