Cadillac 2013 ATS Owner's Manual page 226

9-52 Driving and Operating
WARNING
FCA does not provide a warning
to help avoid a crash, unless it
detects a vehicle. FCA may not
detect a vehicle ahead if the FCA
sensor is blocked by dirt, snow,
or ice, or if the windscreen is
damaged. It may also not detect a
vehicle on winding or hilly roads,
or in conditions that can limit
visibility such as fog, rain,
or snow, or if the headlamps or
windscreen are not cleaned or in
proper condition. Keep the
windscreen, headlamps, and FCA
sensors clean and in good repair.
Collision Alert
With Head-Up Display
Without Head-Up Display
When your vehicle approaches
another vehicle too rapidly, the red
lights, or the collision alert symbol
on the HUD, will flash on the
windscreen. Either eight beeps will
sound from the front, or both sides
of the Safety Alert Seat will pulse
five times.
Tailgating Alert
The vehicle-ahead indicator will
display amber when you are
following a vehicle ahead much too
closely.
Selecting the Alert Timing
With Adaptive Cruise Control