Your Tow Vehicle May Already Have a 'Black Box'
Sandy A. Nicolaysen
truck's on board computer to win court cases:
http://www.montereyherald.com/mld/montereyherald/6195751.htm
Now, the thing that bothers me is that all of the facts in this story
are true. I can use my laptop computer to retrieve maximum speed,
emission limits, seat belt use, etc. Maybe Alan King can clarify us
about the capabilities. I do know that the last few 'events' are
recorded in RAM and can be uploaded to a computer.
Lawyers are going high tech. God save us!
- Sandy
Tom J
"Sandy A. Nicolaysen" <sand...@erols.com> wrote in message
news:sdi1gv4nluepuscmk...@4ax.com...
> Now, the thing that bothers me is that all of the facts in this story
> are true. I can use my laptop computer to retrieve maximum speed,
> emission limits, seat belt use, etc.
Most of that data gathering capability was in Freightliner trucks with the
ND-14 Cummins engine as early as 1993 that I know about, except they stored at
least a month of data that the owners of the truck or Freightliner could
download and make a part of the record of the truck, and incidentally the
driver.
I had the printout laid in front of me after one coast to coast trip I ran
with too little hours down time & a little too much speeding time. :-(
Just like what is still going on today - was told to be careful and keep good
looking logs!
Tom J
Tom J
Neon John
wrote:
Actually that article was quite misleading. Speaking only for GM products
which I am familiar with, the "Sensing and Diagnostic Module" feature is well
known among informed mechanics and is extensively documented in the service
manual. This functionality is actually part of the air bomb control module.
In general, all the inputs to the air bomb module are sampled at high speed
and written to a circular buffer. When the bomb is triggered, the contents of
the buffer are flashed to flash RAM using the remainder of energy stored in
the internal energy storage unit (capacitor). This ensures that the data gets
written even if the crash has severed power to the module.
What gets recorded and for how long is vehicle-dependent. In my 94 caprice,
the buffer length is 17 seconds. I can't recall all of the inputs but ones I
remember include throttle position, RPM, VSS (speed), brake light status
(on/off), ABS status and several other things.
As that article mentioned, this facility was designed into the air bomb
control module for post-deployment diagnostics. The data stream was encrypted
but the encryption was so weak that it was quickly broken. The Big Two
decided to make some money on the situation by licensing the readout
technology to Vetronix and other companies.
The way to defeat this logging function is the same as the way to remove the
potential of severe injury from the air bomb - remove the fuse to the air bomb
controller.
>
>Lawyers are going high tech. God save us!
The major problem with the scumbag lawyers being allowed to use this data is
that it is a perfect example of GIGO - Garbage in, Garbage out. The SDM was
not designed to log data with any degree of absolute accuracy. For the
intended purpose, only reasonable accuracy and linearity does the job. Trends
are more important than absolute values in most instances. That's the first
major problem.
The second major problem is that the data sources are not reliable. Having a
lot of experience with race car data logging, I understand just how hard it is
to get accurate and repeatable data using systems designed for the purpose.
Example: The vehicle speed input is actually the drive shaft RPM as signaled
by the Vehicle Speed Sensor (VSS). This is fine within the envelope of normal
operation. It produces garbage during an accident sequence when the drive
wheel(s) may be off the ground and the throttle position uncontrolled.
Consider a situation where the driver drifts to the median, loses control,
hops the berm and collides with someone traveling in the other direction. The
impact with the berm will likely result in at least some of the wheels being
airborne. Simultaneously the impact may G-load the driver's foot and leg
enough to press on the accelerator. This causes an open throttle signal to be
recorded. And with no load on the airborne wheels, the engine speed and drive
shaft speed accelerate rapidly. At the same time the G-loading of the brake
pedal will move the pedal far enough to engage the brake light.
The readout will show the driver suddenly accelerating and braking at the same
time followed by the impact and air bomb deployment, ending data logging.
Since there are no inputs for actual vehicle speed, pitch, yaw or attitude,
there is nothing to indicate to the person looking at the data that the car
had been airborne and that the data is meaningless. Toss in a lawyer to
intentionally obfuscate the data and the end result is a horrible mess.
As I see it, the real problem is not that the data is being logged. The
problem is that judges are allowing such garbage anywhere near the courtroom.
Unfortunately most judges are lawyers who couldn't hack it in private practice
and are about as technology savvy as my cat so the "computer data" dazzles
them.
John
---
John De Armond
johngdDO...@bellsouth.net
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN