Jeep 2011 Grand Cherokee Owner's Manual page 183

NOTE: When the sensor is removed, Adaptive Cruise
Control, Normal Cruise Control, and Forward Collision
Warning will not be available. The cluster will display the
warning "ACC/FCW Unavailable - Service Radar Sen-
sor."
To reinstall the sensor and bracket assembly reverse the
process above. The fastener torque required to assembly
the bracket back to the beam is 6.6 ft lbs (9 Nm).
ACC Unavailable Warning
If the system turns off, and the EVIC displays "ACC/
FCW Unavailable, Vehicle System Error", there may be a
temporary malfunction that limits ACC functionality.
Although the vehicle is still drivable under normal
conditions, ACC will be temporarily unavailable. If this
occurs, try activating ACC again later, following a key
cycle. If the problem persists, see your authorized dealer.
UNDERSTANDING THE FEATURES OF YOUR VEHICLE 181
Service ACC Warning
If the system turns off, and the EVIC displays "ACC/
FCW Unavailable Service Radar Sensor", it indicates
there is an internal system fault. Although the vehicle is
still drivable under normal conditions, have the system
checked by an authorized dealer.
ACC/FCW Unavailable Warning
3