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: Intake Manifold Components and Components Location
Components
1. Intake manifold assembly 2. Intake manifold gasket3. Electronic throttle body4. Intake manifold stay5. Variable intake solenoid (VIS) actuator6. VCM motor
...
Hyundai Elantra AD (2016-2020) Service Manual: Line Pressure Control Solenoid Valve Specifications
Specifications
? Control type : Normally high type
ShapeItems Specifications Control current(voltage) [mA] 0 ~ 850 Supply pressure [kpa (kgf/cm?, psi)] 539.36 (5.5, 78.23) Control pressure [kpa (kgf/cm?, psi)] 0 ~ 519.75 (0 ~ 5.3, 0 ~ 75.38) Internal resistance( ...