Adjusting instrument cluster illumination

When the vehicle's parking lights or headlights are on, press the illumination control button to adjust the brightness of the instrument panel illumination.
When pressing the illumination control button, the interior switch illumination intensity is also adjusted.
WARNING
Never adjust the instrument cluster while driving. Doing so could lead to driver distraction which may cause an accident and lead to vehicle damage, serious injury, or death.

Instrument Cluster
GaugesHyundai Elantra AD (2016-2020) Service Manual: Temperature Control Actuator Specifications
Specifications
Door PositionVoltage (V)Error DetectingMax. cooling0.3 ± 0.15 Low voltage : 0.1V or less High voltage : 4.9V or moreMax. heating4.7 ± 0.15
...
Hyundai Elantra AD (2016-2020) Owners Manual: Icy Road Warning Light, Electronic Stability Control (ESC) Indicator Light
Icy Road Warning Light
This warning light is to warn the driver the road may be icy.
When the temperature on the outside temperature gauge is approximately below
40°F (4°C), the Icy Road Warning Light and Outside Temperature Gauge blinks and
then illuminates. Also, the warning chime sounds ...