I don't know what manual you have, but they made it crystal clear in mine.
On page 7-9 of my Chevy Cavalier's owner manual:
Vehicle Data Collection and Event Data Records
Your vehicle, like other modern motor vehicles, has a
number of sophisticated computer systems that monitor
and control several aspects of the vehicles
performance. Your vehicle uses on-board vehicle
computers to monitor emission control components to
optimize fuel economy, to monitor conditions for
airbag deployment and, if so equipped, to provide
anti-lock braking and to help the driver control the
vehicle in difficult driving situations. Some information
may be stored during regular operations to facilitate
repair of detected malfunctions; other information
is stored only in a crash or near crash event by
computer systems commonly called event data
In a crash or near crash event, computer systems, such
as the Airbag Sensing and Diagnostic Module (SDM)
in your vehicle may record information about the
condition of the vehicle and how it was operated, such
as engine speed, brake applications, throttle position,
vehicle speed, seat belt usage, airbag readiness, airbag
performance data, and the severity of a collision. This
information has been used to improve vehicle crash
performance and may be used to improve crash
performance of future vehicles and driving safety.
Unlike the data recorders on many airplanes, these
on-board systems do not record sounds, such as
conversation of vehicle occupants.
To read this information, special equipment is needed
and access to the vehicle or the SDM is required.
GM will not access information about a crash event or
share it with others other than
with the consent of the vehicle owner or, if the
vehicle is leased, with the consent of the lessee,
in response to an official request of police or similar
as part of GMs defense of litigation through the
discovery process, or
as required by law.
In addition, once GM collects or receives data, GM may
use the data for GM research needs,
make it available for research where appropriate
confidentiality is to be maintained and need is
share summary data which is not tied to a specific
vehicle with non-GM organizations for research
Others, such as law enforcement, may have access to
the special equipment that can read the information
if they have access to the vehicle or SDM.
If your vehicle is equipped with OnStar, please check
the OnStar subscription service agreement or manual for
information on its operations and data collection.
> Now I have to worry
This seems to be a "hazard" on just about any car that has airbags. On
the other hand, I look at it this way: if I'm driving responsibly (like
I just about always do) and the person I have a collision with isn't,
then more likely than not the SDM will be in my corner, and I will WANT
that data to be used to defend my case. Otherwise, it's my word against
his or hers.
E-mail fudged to thwart spammers.
Transpose the c's and a's in my e-mail address to reply.
2001 Firebird. Page 1-26:
Your vehicle is equipped with a crash sensing and diagnostic module,
which records information about the air bag system. The module records
information about the readiness of the system, when the system commands
air bag inflation and driver's safety belt usage at deployment. The
module also records speed, engine rpm, brake and throttle data.
No mention of "and if you crash, the cops and your insurance company
will seize it to try and determine the cause of the accident."
I have a clean record, I'm just uncomfortable with having an electronic
nanny onboard recording everything incase I might crash. How long until
it's standard for your insurance company and cops to seize them from
That isn't the concern as much as the accurate of the data being
stored and used for a conviction. The average speedometer is 3-5% off
but there are wide variations among that. "Theoretically" if one
wheel was spinning on ice and the other on pavement a 30 MPH accident
could be recorded as 70MPH, or a skidding locked up an 80 MPH accident
could be recorded as 0 MPH for the person spinning into your car.
Or if perhaps you've got a defective speed sensor (not that GM ever
has defective parts installed) incorrect data could be entered into
the computer. I know that I don't know what my ABS data is as it's
travelling down the road.
Perhaps I'm not as trusting of the government as most, just trying
to figure out what new cars would be a secure purchase for me.
Thanks for the info guys
Of course the data needs to be interpreted, same with any other forensic
I don't think it's likely that any major speed measurement error in the case
of a collision would go unnoticed, since the SDM also calculates the
collision delta-V based on the accelerometer readings, which is independent
of the normal vehicle speed indication.
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from firstname.lastname@example.org
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.