Dodge 2014 Charger Owner's Manual page 122

120 UNDERSTANDING THE FEATURES OF YOUR VEHICLE
Overtaking Traffic
If you pass another vehicle slowly (with a relative speed
of less than 15 mph (24 km/h) and the vehicle remains in
the blind spot for approximately 1.5 seconds, the warning
light will be illuminated. If the difference in speed
between the two vehicles is greater than 15 mph
(24 km/h), the warning light will not illuminate.
Overtaking/Approaching