GMC Terrain: Exterior Lighting / Automatic Headlamp System
When the exterior lamp control is set to AUTO and it is dark enough outside, the headlamps come on automatically.
There is a light sensor on top of the instrument panel. Do not cover the sensor; otherwise the headlamps will come on when they are not needed.
The system may also turn on the headlamps when driving through a parking garage or tunnel.
When it is bright enough outside, the headlamps will turn off or may change to Daytime Running Lamps (DRL).
The automatic headlamp system
turns off when the exterior lamp
control is turned to 
or the
ignition
is off.
Lights On with Wipers
If the windshield wipers are
activated in daylight with the engine
on, and the exterior lamp control is
in AUTO, the headlamps, parking
lamps, and other exterior lamps
come on. The transition time for the
lamps coming on varies based on
wiper speed. When the wipers are
not operating, these lamps turn off.
Move the exterior lamp control to 
or 
to disable this feature.
Daytime Running Lamps (DRL)
DRL can make it easier for others to
see the front of your vehicle during
the day. Fully functional DRL are
required on all vehicles first sold in
Canada...
Hazard Warning Flashers
: Press to make the front and
rear turn signal lamps flash on and
off. This warns others that you are
having trouble.
Press again to turn the
flashers off...
Other information:
GMC Terrain 2018-2026 Owners Manual: Rear Cross Traffic Alert (RCTA)
If equipped, when the vehicle is shifted into R (Reverse), RCTA displays a red warning triangle with a left or right pointing arrow to warn of traffic coming from the left or right. This system detects objects coming from up to 20m (65 ft) from the left or right side of the vehicle...
GMC Terrain 2018-2026 Owners Manual: Diesel Particulate Filter
The Diesel Particulate Filter (DPF) system filters soot particles out of the exhaust gases. The DPF is under the vehicle in the exhaust system. Depending on a number of factors monitored by the engine computer, the DPF will need to be cleaned of accumulated solids...
