2010 Mercury Milan Owner's Manual - Page 226

Driving Once blockage is removed, the system will require some driving time and detection of at least two vehicle object prior to realizing it is unblocked, or the driver can cycle the ignition key. If blocked and the ignition key is cycled, the system resets to unblocked. If however blockage is still present after the key cycle, the system will sense again that it is blocked after driving in traffic. The following table lists possible causes and actions for this message being displayed: The surface of the left or right radar is dirty or obstructed in some way The surface of the left or right radar is not dirty or obstructed Clean the fascia area in front of the radar, either left or right side, or remove obstruction. Drive normally in traffic for a few minutes to allow the radar to detect that it is no longer blocked. Note: the vehicle must be in D (Drive) and a few vehicles must pass so that the BLIS can clear a blocked state. No action required by the driver. The system will automatically go unblocked once the rainfall/snowfall rate decreases or stops. Do not use BLIS -CTA in heavy rainfall or heavy snowfall. Heavy rainfall or heavy snowfall is interfering with the radar signals Due to the nature of radar technology, it is possible to get a blockage warning and not be blocked. This is rare and known as a false blockage warning. A false blocked condition will either self clear or clear after a key cycle. Trailer tow false alerts When towing a trailer, the left and right sensor may detect the trailer thus causing a false alert. It may be desirable to turn the BLIS off if the false alerts become annoying. Day and night brightness The BLIS -CTA alert will automatically dim when the headlamp switch is in the parking, on, or autolamp position and night time darkness has been detected by the sun sensor. 226