Try to start it and it wont read rpm.
^^This is an important clue. It will never start without a valid CKP signal reaching the PCM. Note, the CKP sensor generates it's own output voltage. Therefore it doesn't need power to work.
Soooooooo. If no CKP sensor signal please check:
- CKP trigger wheel? Did you remove the timing cover? If so, did you remember to reinstall the trigger wheel? Is it installed in the correct direction? Note, you should be able to see the reluctor wheel teeth through the CKP hole.
- CKP sensor not installed correctly. For example not pushed in all the way.
- Bad CKP sensor, Disconnect the electrical connector. Measure the Ohm resistance of the CKP coil.
- Wiring harness fault between the CKP sensor and PCM. If this is suspected best to "ring out" the wires between the CKP sensor directly back to the PCM.
Here's some more information about "crank with no start" check list. Note the part about noting IF the check engine light goes out during cranking which indicates the PCM is "seeing" a CKP sensor signal. 1996+ Crank with no start check list https://www.allfordmustangs.com/forum...e.html#2984838
Note, since the CKP sensor generates it's own voltage it's possible to perform a "functional" test by disconnecting the electrical connector and reading AC voltage with a Volt-Ohm meter during cranking. If you see any voltage likely the CKP sensor is working. Look else where.