remote entry -key fob programming

"Ted Mittelstaedt" > wrote in message
...
>
> "maxpower" > wrote in message
> . ..
> >
> > "MoPar Man" > wrote in message
> > ...
> > > maxpower wrote:
> > >
> > > > The RKE system and transmitter use a rolling code method ...
> > > > The transmitter sends a randomly selected sequence code each time
> > > > The code increments vary depending on a unique algorithm that
> > > > is preprogrammed to each transmitter at the time it was built.
> > > > The sequence changes each time the transmitter is used.
> > >
> > > > the sequence code cannot be calculated from the encoded
> > > > transmission. The receiver module also learns the transmitter
> > > > id code
> > >
> > > So far, what you're saying is that the FOB sends out a different
> > > sequence each time it's pressed, and that the ID code of the fob can
> > > be uniquely calculated from the transmitted data stream based on an
> > > algorythm.
> > >
> > > I doubt that the fob actually does generate a completely different
> > > stream each and every time it's pressed, as I doubt that the designers
> > > would ever anticipate someone with enough electronic gear would be
> > > close enough to the car to (a) want to open/unlock the car without
> > > possessing the real fob or key, (b) be close enough to evesdrop and
> > > capture the transmission, and (c) possess the electronics required to
> > > replicate the transmission. Just consider a use-case situation.
> > >
> > > But even if the fob does generate a different stream each time it's
> > > pressed, then I guess the receiver in the car would have to never
> > > respond to the same stream twice.
> > >
> > > > and initial sequence code at the time of transmitter programming.
> > > > The receiver then expects the next transmitted sequence code to
> > > > increment within a predetermined range of numbers
> > >
> > > Now that has got to be total bull****.
> >
> > Your right it has to be total bull****, But it isnt, google rolling
code!!
> > No wait, I will do it for you. http://en.wikipedia.org/wiki/Rolling_code
>
> maxpower, there is nothing in this description that would preclude
> the original poster from programming the same keyfob to open multiple
> cars - as long as the keyfobs were the same part number AND as
> long as the system didn't have a different set of pseudo random number
> generators. (PRNGs)
>
> If for example the transmitter had a table of, lets say 200 different
> PRNGs, and during keyfob programming the transmitter uploaded
> a selected PRNG to the keyfob, then you would have a problem
> doing it. What would happen is both vehicles would likely use a
> different PRNG.
>
> But, if the PRNG's are only different between vehicle models, and
> or years, and the PRNG was burned into the keyfob, then as long
> as both cars used the same PRNG you could do it.
>

Keep in mind that when you program one remote on this system you have to
program all at the same time. Or it wipes out the ones that you didnt
program.


> I can guarentee to you that at least up to 1995 Chrysler did in fact
> use fixed PRNGs in the RKE system. In fact the sequence generator
> was the same algorithim for multiple YEARS. That is why I was
> able to program both my '94 and '95 van to use the same keyfobs.

You were able to do your older vehicles because it was not using the rolling
code system I would think. when program a key fob into that year you didnt
have to have all of them to reprogram. You were able to add one
>
> They changed the remotes in 96, and I would assume the system
> as well. But, if the new keyfobs are transmit-only, then it would be
> very likely that keyfobs of the same part number would use the
> same PRNG and would work.
>
> Frankly the entire system is way overengineered. A thief simply
> walks up to the car and smashes the window with a rock, he does
> not bother fiddling around with sniffing RKE signals.

I beleive the key fobs were designed more to lock and unlock doors
easier.... not to deter thiefs. The skim key is to deter thiefs from
stealing the vehicle. and the vehicle theft alarm was to deter them
>
> Ted
>
>

>> maxpower, there is nothing in this description that would preclude
>> the original poster from programming the same keyfob to open multiple
>> cars - as long as the keyfobs were the same part number AND as
>> long as the system didn't have a different set of pseudo random number
>> generators. (PRNGs)
>>

>Keep in mind that when you program one remote on this system you have to
>program all at the same time. Or it wipes out the ones that you didnt
>program.

This is the OP checking in. I've been following the discussion and I'm
now at the point where I'm not sure I want to try the process for fear
of ending up with no fob that works! My fobs do have identical Part #
and FCC ID # for what that's worth (the vehciles were 1999 and 2000).
And the process described in the owners manual gives the steps to
program a different fob to work with the car but is silent about
having to apply the process to the existing fob. I can't afford to
have the dealer fix anything I screw up. Maybe I'll just continue
using the low-tech key when I have to use my wife's car :-)


John Keith

"Bill Putney" > wrote in message
...

> in this case, if you think about it,
> the development costs of such systems are amortized over practically all
> new cars on the planet (I'm assuming the algorithms and chips all come
> from a handful of manufacturers), and the per-unit costs are probably
> not increased much at all.

Understandable, the problem is that this ALSO applies to things such
as the human interface to the engine computer.

Why does it take a $10,000 scantool to interrogate the computer?
Car computers today could be fitted with an USB port and you
just plug in the laptop and run some software on it that interrogates the
computer. Or better yet as I've said before, put an ethernet port
on the car computer and put a webserver in it, and jack in your
laptop running a web browser and use that to interrogate the
computer.

> IOW, there is some slight benefit overall,
> but the cost is almost zero compared to a, say, pre-'96 system. It's
> not like some feel-good systems that are on our cars now or in the
> future from which the benefits are questionable but the added cost per
> vehicle is one or more hundreds of dollars.
>

Systems like the car computer interface which would cost almost
zero due to amortization, yet deliver massive benefits, are not
implemented. Systems like powered running boards that do
nothing other than make the vehicle look like a rolling Christmas
tree, ARE implemented. Is it any surprise Chrysler is this close
to bankruptcy?

Ted

Ted Mittelstaedt wrote:

> Why does it take a $10,000 scantool to interrogate the computer?
> Car computers today could be fitted with an USB port and you
> just plug in the laptop and run some software on it that interrogates the
> computer. Or better yet as I've said before, put an ethernet port
> on the car computer and put a webserver in it, and jack in your
> laptop running a web browser and use that to interrogate the
> computer.

That's been available for years - I own a third party tool that plugs
into the car's datalink connector and adapts to the USB port of a
computer (typically a laptop) into which you load the tool's software
(basically your computer and the software comprise the "tool").

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

"Bill Putney" > wrote in message
...
> Ted Mittelstaedt wrote:
>
> > Why does it take a $10,000 scantool to interrogate the computer?
> > Car computers today could be fitted with an USB port and you
> > just plug in the laptop and run some software on it that interrogates
the
> > computer. Or better yet as I've said before, put an ethernet port
> > on the car computer and put a webserver in it, and jack in your
> > laptop running a web browser and use that to interrogate the
> > computer.
>
> That's been available for years - I own a third party tool that plugs
> into the car's datalink connector and adapts to the USB port of a
> computer (typically a laptop) into which you load the tool's software
> (basically your computer and the software comprise the "tool").
>

Yes, I know about those tools but that isn't what I'm talking about.
The CPUs today used for embedded electronics like a vehicle car
computer have plenty of extra power and the entire software that is
in the tool could be easily stuck into the car computer - thus turning
your laptop into nothing more than a human interface device, and alleviating
the need to buy the software and the adapter that goes from the
datalink connector to the USB port (which if you were to take it
apart you probably would find quite a lot of intelligence in the adapter)

Remember, the software on the computer needs to read lots of
different models of cars, so it's much larger than it would need to
be if included in the car computer.

The federal government standardized the OBD-II connector over
a decade ago, today there's much more common computer industry
standard interfaces - ie: USB, firewire, and ethernet - where the
controllers for these interfaces are much cheaper due to the fact
that they aren't single-sourced. It's high time that the OBD-II
interface be retired and replaced with one of these so you can just
use an off-the-shelf $5 cable to plug your PC into the car computer.

Ted

"maxpower" > wrote in message
. ..
>
> "Ted Mittelstaedt" > wrote in message
> ...
> >
>
> You were able to do your older vehicles because it was not using the
rolling
> code system I would think. when program a key fob into that year you
didnt
> have to have all of them to reprogram. You were able to add one

No, in the older vehicles you have to program all the fobs in at the same
time also. But the programming method is different, it involves grounding a
wire and pushing buttons on the fobs, none of this business of requiring 2
working fobs beforehand. When I did it, I programmed the first vehicle
then the second vehicle.

The older system only allows a max of 2 fobs to be programmed.

I'm also pretty sure it's a rolling key system, but I think it's a standard
PRNG algorithm for all of the fobs.

Ted