#filament

Robin writes:

Hi Sajeev,

It’s me again, steady reader, random poster/questioner, with another D21 question. My good old ’94 Nissan D21 is soldiering on, 213,000 and steady on. Of course I don’t ever thrash it which I’m sure makes a difference.

But to get to the point: the other day I went out to go to work and presto! No low beams. High beams, check. All signals, markers and brake lights, check. Just no low beams.

TTAC commentator Celebrity208 writes:

Sajeev:
I’d always thought that police crash investigators would check the tail light bulbs of a car that was rear ended to determine if its lights were on at the time of the crash. I thought it had something to do with the way the filament was broken/burnt/etc. So my question is two-fold, am I crazy and do they do this, and if so how might LED tail lights remove this piece of forensic evidence regarding correctly operating brake lights at the time of an accident (presuming the fault was contested)?