Re: Reprogramming digital odometers

[Jim Cash <j.cash@xxxxxxxxxxxx>]

Suzy Kraft writes:

> I thought digital odometers could only be reprogrammed by an authorized
> dealer.  I found a device called the DiaProg Compact (www.megachip.de)
> that claims to be able to reprogram most digital odometers, including
> those used on most  BMWs. Does anyone know if this thing really works?

Suzy

I had an electronic exchange with someone in Europe last year about this
issue. Apparently there are a number of devices out there that are able
to change the odometer reading in the dash.

BUT - there is another issue.

The later BMW's (E38 & E39 for sure) have a process whereby the mileage
is "backed up" in another component in the car. The instrument cluster
sends a software message to the other component every 100 km's, so that
the back up data is never more than 100 km=92s different than the reading
on the dash.

Every time the car is started the 2 data files are checked (as is the
VIN which is also stored in the redundant location). If there is a
mismatch in the mileage greater than 200 km=92s, then an "error" is set i=
n
memory in the instrument cluster.  If there is a mismatch in the VIN,
the cluster sets the "tamper indicator" - a small red led next to the
tripmeter reading on the E39.=20

And, the mileage data stored in the backup location can only be
overwritten by a "higher" value.

I am not identifying the backup component on purpose.


If the odometer is reset to 0 then the instrument cluster will reset it
again to the mileage stored in the backup component the next time the
car is started.  But, if the odometer is set to anything other than 0
then the only thing that happens is the error code being set ( as
mentioned earlier ).


In theory a device that can change the odometer reading could also find
and cancel any error code, but that code should be set again when the
car is started.  Sooooo - if someone turns an odometer back fraudulently
there should always be a telltale error in the memory of the instrument
cluster.

I understand that if you need a new instrument cluster, it is delivered
from BMW  with the VIN number assigned to it - for your car, and the
mileage set to 0.  The unit then restores all other data from the back
up source as long as the VIN numbers validate. (other data includes all
SI information).


Hope that helps.

Cheers

Jim Cash


PS  If man evolved from apes, why do we still have apes?

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