For the 96-98 model year the anti-theft system (PATS) disables the starter. This gives a no crank symptom.
The 99-04 MY, PATS disables fuel and spark. This gives a crank with no start symptom.
Turn the key on but do not crank. Does the theft light go off after a 3 second prove out? If not, STOP and find out why?
Does the theft light come on during cranking? If yes, STOP and find out why.
For a PATS problem, first try reseting with the key FOB and/or by unlocking the driver's door with the key.
Do you have another key to try?
Try jumping the starter solenoid to see if the starter engages.
A no crank can can also be the neutral safety switch (clutch or park).
>>TSB 01-6-2 PATS — diagnostic tips http://www.stangnet.com/images/stori...s/01-06-02.pdf
Late model cluster diagnostic http://www.allfordmustangs.com/forum...stic-mode.html
>>>>Spare key programming procedure 96-98 Model year.
Spare Key Programming
control modules require only one key to be programmed before allowing the vehicle to start. If a control module is changed, the technician must inform the customer to program any additional keys using the Spare Key Programming procedure detailed in the Owner Guide.
The system has capacity to store a maximum of 16 keys. After the initial key has been programmed or using any programmed key, follow the steps below:
Encoded keys must have correct mechanical key cut for vehicle.
l Cycle ignition switch from RUN to OFF with a programmed key.
l Within 15 seconds after this cycle, insert a new encoded key into ignition switch and turn to RUN or START.
l If programming is successful, the THEFT indicator will illuminate for two seconds and the control module will enable the vehicle to start.
l Repeat until all chosen keys have been programmed, up to 16 keys total.
l If programming is not successful, the THEFT indicator will:
-- Flash for one minute if no key code is received. The key is either damaged or is a non-encoded key. (Try a new key and start procedure over again.)
-- Flash for 15 minutes if key code is received yet vehicle is disabled. The key was not programmed successfully. Start procedure over again.
l If programming is not successful, possibly the new key was not inserted within 15 seconds, all 16 key codes have been stored, or the key is a non-encoded key. If the key was not encoded or inserted within 15 seconds, repeat procedure.