Need Help With Anti-theft System

Is the cluster displaying all dashes (------)?

Turn the key on but do NOT crank. Does the theft light come on and then go off after a 3 second "prove out"? Tell us exactly what the lights are doing. Don't be in a hurry to crank it.

This may not be a PATS problem at all.

1996+ Crank with no start check list
http://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838

Hurstie77 said:

We towed it home today and it's now in the garage with the battery unhooked. Someone else posted to completely unhook the battery and let the car sit for a couple of days. I doubt that will work either ....

Click to expand...

So do I.

The crank with no start check lists has a number of specific tests meant to be performed in order. The results of each test provides clues as to WHERE to focus looking for the problem. It not just a series of tests to be done and that's it.

The theft light flashing fast does indicate a PATS "issue". But as I stated before you really don't KNOW if the problem is in the PATS system itself or in the PCM.

One of the tests is to turn the key on but do NOT crank. Listen for the fuel pump to run. Do you HEAR the fuel pump run? IF the fuel pump runs for a few seconds at initial key on, this indicates the PCM is alive and working at some level.

Does the check engine light go off during cranking? If yes this means the PCM is getting a good CKP sensor signal. It also means the PCM is alive and functioning at some level.