Jeep 2014 Grand Cherokee Owner's Manual page 137

UNDERSTANDING THE FEATURES OF YOUR VEHICLE 135
Overtaking Traffic
If you pass another vehicle slowly (with a relative speed
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
3
between the two vehicles is greater than 15 mph
(24 km/h), the warning light will not illuminate.
Overtaking/Approaching