Ignition what ? Switch ,Ignition lock cylinder ? New keys ? do they have the transponder pellet in the head. Do you have a security lit flashing when trying to start the vehicle ?
SECTION 419-01: Anti-Theft - PATS
1999 Mustang Workshop Manual
Procedure revision date: 11/06/1998
Key Programming -Erase All Key Codes and Program Two Keys
New Generation STAR (NGS) Tester or equivalent
NOTE: This procedure is used when a customer needs keys programmed into the system and does not have two programmed ignition keys available. This procedure is also useful when programmed ignition key(s) have been lost or the ignition switch assembly has been replaced, and it is desired to erase key(s) from the passive anti-theft system (PATS) memory.
NOTE: This procedure will erase all programmed ignition keys from the vehicle memory and the vehicle will not start until two keys have been reprogrammed to the vehicle.
NOTE: Two PATS encoded keys with the correct mechanical cut must be available to perform this procedure. One or both of them may be the customer's original keys.
NOTE: If additional keys are to be programmed, refer to Key Programming - Program a Key Using Two Programmed Keys. If the remaining keys are with the customer and are not available with the vehicle, then instruct the customer to refer to the Owners Guide under the "Programming Spare [SecuriLock ® (North America), Safeguard ® (U.K.) or PATS for all other markets] Keys Procedure" for instructions on programming the remaining keys.
- Turn the ignition switch from OFF to RUN.
- Enter New Generation STAR/Service Bay Diagnostic System (NGS/SBDS). Follow the SECURITY ACCESS PROCEDURE to obtain security access.
- From NGS/SBDS menu, select IGNITION KEY CODE ERASE.
NOTE: Do NOT select any additional commands from this menu.
Turn the ignition switch to OFF and disconnect NGS.
- Insert the first encoded key into the ignition lock cylinder and turn the switch to RUN for three seconds.
- Insert the second encoded key into the ignition lock cylinder and turn the switch to RUN for three seconds.
- The vehicle should now start with both ignition keys.
You'll need to take to the dealer