CRC checksum and signature Rolls Royce/BMW error or bypass?

[TJCollins]

Good morning,

We are investigating a collision loss on a 2021 Rolls Royce Cullinan. The VIN conforms to VIN standards, however, the Serial Number is *Out of Range... ie; never produced by the mfg. As it was involved in a collision, we imaged the EDR through the DLC/OBDII port. It did read the VIN during the imaging process, HOWEVER, I believe the OBDII port was bypassed for VIN identification. Oh yeah, it may be a VIN switch...

During the imaging process, the CDR tool read the VIN, but that's the whole idea of the bypass, to have it read the VIN you programed into the bypass.

I have analyzed many BMW's EDR, however, have never seen this line in the Hexadecimal Data, "FA18 No Data received (CRC checksum and signature did not complete successfully)" In other BMW's, FA 18 simply says "No data received".

The software reads the data three times prior to imaging it and if any bits or bites do not match, it normally advises the user the imaging was unsuccessful. BMW has an internal integrity check within the vehicles system prior to giving the report to the user, and since it appeard in the Hexadecimal Data, I am wondering if that is why there is a
CRC error.

Does anyone have any experience similar to this or know where I can find more information?

ANY thoughts are greatly appreciated!

Tracy