Jeep 2011 Grand Cherokee - Owner Manual - Manual (Page 119)

The BSM system is designed not to issue an alert on
stationary objects such as guardrails, posts, walls, foliage,
berms, etc. However, occasionally the system may alert
on such objects. This is normal operation and your
vehicle does not require service.
Overtaking/Passing
Stationary Objects
3
UNDERSTANDING THE FEATURES OF YOUR VEHICLE 117