Decoding puzzle

[ClaretSupporter]

Originally Posted by Phil-T4

I'm feeling pretty pleased with myself as it only took me 3 hours to work this out..

Here is your challenge if you wish to accept it

Here are two encoded VIN numbers that i read from different EWS ecu's.

1C29B6D371D64B0CD088241041
1C29B6D345544C896046084046

Here are the decoded VIN's for the above

SARRJSTPB3D289111
SARRJHLHCYM162416

How is it done?

Good Luck
Phil

The coding is straight forward compression. There are 36 characters required which requires a total of 6 binary bits per character. As identified by others this gives the coding
0 -> 0x00 = 000000
1 -> 0x01 = 000001
2 -> 0x02 = 000010
3 -> 0x03 = 000011
.
.
.
9 -> 0x09 = 001001
A -> 0x0A = 001010
B -> 0x0B = 001011
.
.
.
Y -> 0x22 = 100010
Z -> 0x23 = 100011

To represent a 17 character VIN we require 17 * 6 = 102 bits.

Modern communication systems use 8 bit characters to transmit data so we can take this string of 102 bits and split it into 13 8 bit characters. As 13 * 8 = 104 we have to pad the 102 bits with an extra two zeros at the front.

The first example with padding becomes
S A R R J S T P
00 011100 001010 011011 011011 010011 011100 011101 011001
B 3 D 2 8 9 1 1 1
001011 000011 001101 000010 001000 001001 000001 000001 000001

Regrouping into eight bit bytes we get

00011100 00101001 10110110 11010011 01110001 11010110 01001011
1C 29 B6 D3 71 D6 4B
00001100 11010000 10001000 00100100 00010000 01000001
0C D0 88 24 10 41

I hope this explanation will show why the algorithms described in this thread are required to split the sequence of 8 bit bytes into a sequence of 6 bit bytes.

[Phil-T4]

Excellent explanation - thank you

[Avulon]

And here's an Excel spreadsheet to make it easy, (can you tell I really don't want to be doing what I'm supposed to be doing ).

[ClaretSupporter]

For people who prefer a picture to my explanation above, the following web page will show the mapping from either a coded or an uncoded VIN. It also provides a decoding of the various components using the information provided by Reebs.
click here

[tomcat22]

Do you know what the "ECD" stands for?
ECD options are none, ECD2 & ECD3

Originally Posted by Conni

Hello Together,

here the meaning of the HexCodes of the code ZCS.
The Checksum is in brackets and here it concerns not HexCodes,
but these are with the biggest likelyhood Alphanumerics.
I cannot say the other to the Checksum,
because moreover I myself still look for explanations.

GM
73220121(5)

7=R75-Basis, 3=M47R, 2=2.0 Liter,2=RHD, 0=GM5 no choice like zero, 1=UK, 2=Manual, 1=English UK

SA
422748C08700843A(J)

4=Tourer, 2=Alarm withUS, 2=RainSensor, 7=(4=PDC KMC Sounder, 2=PDC, 1=RearWashWipe),
8=CruiseControl, C=12(8=OneShut Up, 4=OneShut Down), 0=SA7 no choice, 8=ATC Aircon,
7=(4=NoRearPretensioner, 2=AirbagCourtain, 1=SideAirbag), 0=SAA no choice, 0=SAB n.choi.,
8=EOBD, 4=Diesel Fuel, 3=(2=ECD 2, 1=ACU C10), A=10(8=AntiTrap, 2=el.Front+Rear Window

VN
1800001043(W)

1=XPOWER, 8=135 PS, 0=no choice, 0=no choice, 0=VN4 no choice, 0=VN5 no choice,
1=PDC 003, 0=VN7 no choice, 4=KBM C04 Rover-Diesel, 3=(2=LSM C28, 1=GM6 C04)

that's it!

I have found into two queries concerning 'RainSensor'.
Both have in each case the value 2, but in different positions.
Sometimes becomes after 'RainSensor' asked and sometimes after 'RainSensor G2'.
If different versions are meant herewith or somebody can give me an explanation moreover.
If so, then already Thanks in Ahead.

Greetings

Conni

[BigRuss]

Originally Posted by tomcat22

Do you know what the "ECD" stands for?
ECD options are none, ECD2 & ECD3

European Commission Directive 2 or 3

It's the Euro emmisions rating.

Russ

[tomcat22]

Originally Posted by BigRuss

European Commission Directive 2 or 3

It's the Euro emmisions rating.

Russ

Many thanks. Imho ECD2 does not make sense for our cars.
Also not sure how if it changes anything