Cadillac 2011 DTS Owner's Manual page 146

LDW uses a camera located between the inside
rearview mirror and the windshield to detect the lane
markings.
off, press the LDW control, located by the exterior
headlamp control. An indicator on the control will light
to indicate that LDW is on.
When the vehicle is started, the LDW symbol, located in
the instrument panel cluster, will briefly come on to
indicate that the light is operational.
3-44
To turn LDW on and
LDW only operates at speeds of 35 mph (56 km) or
greater. If LDW is turned on when traveling at these
speeds, the LDW symbol will appear green if the
system detects a left or right lane marking. This symbol
will change to amber and flash and three beeps will
sound if you cross a detected lane marking without
using the turn signal.
If the LDW symbol does not appear, LDW is not
currently operating and will not warn you.
To change the volume of the warning chime, see Chime
Volume under DIC Vehicle Customization on page 4 74
for more information.
The LDW symbol will not appear when the system is
having difficulty seeing the lines on the road or if the
view of the camera on the windshield is blocked with
mud, dirt, snow, ice, or slush, if the windshield is
damaged, or when weather limits visibility, such as
while driving in fog, rain, or snow conditions. This is
normal operation, the vehicle does not need service.
For cleaning instructions, see Washing Your Vehicle on
page 6 98.
LDW warnings may occasionally occur due to tar
marks, shadows, cracks in the road, or other road
imperfections. This is normal system operation, the
vehicle does not need service.