Symptoms:
It is a common phenomenon that Mercedes Benz Vito/Viano, W636/W639 doesn’t show mileage at all after replacing second-hand instrument cluster.
Cluster (new type ) Eeprom: 25LC640 (25640)
Solution:
Disassemble the instrument cluster, remove dashboard, locate chip IC 25LC640, read 25640 chip data with CG100 or CG Pro 9S12 programmer
Save eeprom.
How to modify data:
The red frame is the mileage area, which can be changed to 0.
The blue frame is the synchronization ID (SSID) of the instrument cluster and the key, which needs to be modified according to the SSID of the current key.
For mileage to show, mileage+ssid must match EZS.
Read working key information with CGDI MB. Write down the SSID and key position
Current key position: 2
SSID:69 6F 44 40
The first key SSID should be 68 6F 44 40
97 90 BB BF Back to front： BF BB 90 97
BB=44, BB verification： B4 4B
90=6F, 90 verification：9F 60
97=68, 97 verification：98 67
Before modification vs After modification
Write the modified chip data to cluster.
Reinstall instrument cluster to vehicle.
Dashboard shows the correct mileage, all data work properly.
Done.
http://blog.obdii365.com/2022/10/10/mercedes-w636-w639-not-show-mileage-cgdi-solution/
