taillamp bulb forensics

[CARIBOULH@xxxxxxx]

Gary Stark had wondered:

"In talking to the Mercedes rep about the incident, he is reporting to
 her that there is a way, within either the taillamp or the bulb, to
 determine if the brakes were actually applied at the time of impact."

This is actually very simple and can be done with any type of vehicle, not
just a Mercedes. Assuming that the filament in the bulb is broken by the force
of the impact, you can simply examine the broken ends of the filament to
determine whether or not it was glowing (meaning hot) when the break occurred.
The newly exposed ends of the break will oxide instantly due to the heat in
the filament and there can also be evidence of arcs from sparks as the voltage
tries to jump across the tiny gap that opens as the filament breaks. The logic
is that if the ends of the broken filament show evidence of this, then the
filament was hot and glowing, and the brake lights were on because the brake
pedal was depressed. A cold filament that breaks will exhibit completely
different characteristics on the broken ends. Because of the very fine size of
the filament wire, even if the brakes were on and then released, the filament
cools almost instantly, so it's condition when examined is usually a quite
accurate indicator as to brakes on or brakes off at any point in time.

Best Wishes,

Ed at Caribou Imports, Inc.
NOW... the largest Fiat parts supplier in the Western U.S.
visit us on the Web at:
www.caribou.cc
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