Re: HIDs-Long

[Scott Mockry <sjmauto@teleport.com>]

John and Graydon,

At 01:09 PM 8/9/99 -0400, john r. cummings wrote:
<SNIP>The HID lights make the euro lights seem dim by comparison, but
>that's where the benefit ends. The HID lights skim along the road at about 36
>inches off the ground with no diffusion. They are brillaint where they shine
>but they cut off with a razor sharp line to pitch blackness. Any bump, hill,
>curve,  or change in acceleration or braking changes the angle of the lights
>. On the curvy roads around here I have entered downhill corners with
>mailboxes and garbage cans in full view only to have them completely
>disappear form view momentarily. <SNIP>

The sharp cut off can cause problems as mentioned even on the Euro lights
if the adjustment is set too low.  Having the electric adjuster servo
motors on the Euro lights helps prevent this problem, a local friend has
these electric adjusters on his 1991 200TQ, and they are great for setting
the light cutoff, when there are changes in vehicle loading.

 According to the Service Training booklet, "1998 Audi A6" WSP-521-229-00,
the 1998 A6 with the HID's have an automatic/Static Light Span Adjustment
system. I believe this automatic adjustment system is required on vehicles
with HID lighting. Possibly, this automatic system has a basic adjustment,
or a fudge factor adjustment that needs to be corrected on some vehicles to
optimize the light cutoff level?

To quote this training booklet:
"Vehicles with gas discharge headlamps as optional equipment require a
cleaning system and an automatic light span adjustment program. 

The automatic/static light span adjustment in the Audi A6 adapts the
headlamp adjustment automatically to the load condition. In a stationary
vehicle, the starting position adjustment occurs as soon as the ignition
and the light are switched on. During driving operation, subsequent
adjustments occur in specific intervals, with shorter intervals at high
speeds. This compensates for the decreasing fuel level. Static means that
dynamic vehicle body motion, such as during braking and acceleration, are
not corrected.

Sensors determine to what extent the front and rear axles are spring
deflected. The controller determines the load condition from the
difference. The multi-purpose instrument transmits the speed signal to the
controller for light span adjustment. This is how it recognizes the moving
condition. Then the servo motors adjusts the headlamps to achieve optimum
illumination of the road." 

end quote.

HTH
Scott (gas discharge) Mockry