Coupe GT digital dash washout

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <9708061954.AA25012@fluhr.austin.ibm.com> ejfluhr@austin.ibm.com (Fluhr) writes:

> This digital dash has an automatic brightness control?  I wasn't aware of
> that.  I know it has a light sensor located in the left side vents of
> the instrument cluster housing, but I thought that was the dummy-light
> warning.  Does this also control the brightness of the dash?

Not on my car.

If you look carefully to the right of the little panel with all the
warning lights, below the speedometer/odometer, you'll see a little
circular aperture in the frame.  This is the photocell that regulates
dashboard brightness.

The best way to see the effect is with an AARON Bend-a-Light[TM] Pro.
Leave the cover on, position the open end over the aperture, and switch
on.  The change in dashboard brightness is startling, to say the least.

Oddly, the ramp times are different for 'on' and 'off'.  It reacts
_very_ quickly to increased light, but quite slowly to reduced light.
Very, very logical when you consider its purpose and human physiology.

It looks like there's a small lens in there, so the photocell is
effectively taking a brightness reading off the driver.  My guess
is that tinting the windows in the rear of the car is substantially
fooling the photocell into thinking it's dark outside and the driver
should not be blinded by a too-bright display.  Of course, the driver
is actually looking out through an untinted windscreen at an undimmed
summer day, and actually finds the dashboard next to invisible.

--
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club