Prometey, did you manage to find which CAN commands dump bytes from ROM?
By the way flash can be read by checksum calculation command. For example for TCM module 7A:
1. Start sending sleep message for 2 secs with 100 ms interval:
0xFFFFE 0xFF 0x86 0x00 0x00 0x00 0x00 0x00 0x00
2. Switch TCM module to programming mode:
0xFFFFE 0x7A 0xC0 0x00 0x00 0x00 0x00 0x00 0x00
3. Send start add for checksum: AABBCCDD - addr from 0xF0000 down
0xFFFFE 0x7A 0x9C 0xAA 0xBB 0xCC 0xDD
4. Send get checksum with next byte:
0xFFFFE 0x7A 0xB4 0xAA 0xBB 0xCC 0xDD+1
5. Read response from TCM.
6. After all flash is read send CAN reset message.
0xFFFFE 0xFF 0xC8 0x00 0x00 0x00 0x00 0x00 0x00
Looks like this approach can also be used for ECM module read.