Cadillac 2011 STS Owner's Manual page 225

The HUD controls are located to the left of the steering
wheel on the DIC control panel.
Turn the brightness control knob fully
counterclockwise to turn the HUD display off.
up or down on the windshield. HUD cannot be adjusted
side to side.
Press to move the HUD display
Press the knob on the center of
the DIC control panel to extend and then pull the knob
until is completely extended. Turn the knob clockwise or
counterclockwise to increase or decrease the
brightness of the HUD display.
To adjust the HUD so it can be seen properly:
1. Adjust the seat to a comfortable driving position,
before adjusting the HUD position.
2. Start the engine.
3. Adjust the position and brightness of the HUD
display.
The brightness of the HUD display is determined by the
light conditions in the direction the vehicle is facing and
where the HUD has been positioned on the windshield.
If the vehicle is facing a dark object or a heavily shaded
area, the HUD may begin to dim because it anticipates
the vehicle entering a dark area.
When sunlight enters the HUD it can make it difficult
to see the display. The display will return to normal
brightness when the sunlight no longer enters the HUD.
Wearing polarized sunglasses could also make the
HUD display harder to see.
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