Software is not necedssarily needed, speedometer needles have stuck at speed
in accidents many years before onboard computers were installed on cars.
Roy
"Steve W." > wrote in message ...
> panabiker wrote:
>> Over the weekend, I had a conversation with some friends on a recent
>> accident involving NJ governor. It was reported by news media that the
>> SUV was going at 91 MPH prior to the crash. My question was how they
>> found out the speed, and one answer was that a speedometer would stuck
>> at the speed the moment of the impact. I find it very hard to believe
>> that any speedometer would stuck at the correct reading considering
>> the violent nature of the collisions, unless the speedometers are very
>> specially designed to record speeds and to sense the crash. Can anyone
>> shed some lights on how accident investigators figure out the crash
>> speeds?
>>
>
> Easy to do IF you have access to the proper software. They just plug into
> the OBD port and query the airbag module for the vehicle parameters at the
> time it deployed. It saves the information just like the freeze frame data
> that gets stored when the MIL comes on. It will tell them the speed,
> throttle position, engine RPMs, in what order the sensors for the
> bag(s)tripped,if you had the brakes applied (also shows if ABS was
> functioning at the time), seat belt use, exterior temperature. Plus a few
> other items.
>
>
> --
> Steve W.
>