Chevrolet 2004 Corvette Owner's Manual page 134

Be sure to continue scanning your displays, controls
and driving environment just as you would in a vehicle
without HUD. If you never look at your instrument
panel cluster, you may not see something important,
such as a warning light. Under important warning
conditions, the CHECK GAGES icon will illuminate in
the HUD. View your Driver Information Center (DIC) for
more information.
3-20
The HUD controls are located to the left of the steering
wheel.
To adjust the HUD so you can see it properly, do the
following:
1. Start your engine and slide the HUD dimmer control
all the way up.
The brightness of the HUD image is determined by
the light conditions in the direction your vehicle is
facing and where you have the HUD dimmer control
set. If you are facing a dark object or a heavily
shaded area, your HUD may anticipate that you are
entering a dark area and may begin to dim.