Ford 2003 Mustang Workshop Manual page 3553

switch is turned to RUN or START under normal operation. If there is a PATS problem, this indicator
will either flash rapidly or glow steadily (for more than three seconds) when the ignition switch is turned
to RUN or START. PATS also "blips" the theft indicator every two seconds at ignition OFF to act as a
visual theft deterrent.
The PATS is not compatible with aftermarket remote start systems, which allow the vehicle to be
started from outside the vehicle. These systems may reduce the vehicle security level, and also may
cause no-start issues. Remote start systems must be removed before investigation of PATS-related
no-start issues.