AACAN2 on the basboard is conneted internally to both FCU and Jetson module. The basics could be implemented from Nvidia user guide:
Controller Area Network (CAN) Jetson Linux Developer Guide documentation

However, you could follow the below quick commands might make you able to loopback test the CAN connection between Jetson module and FCU on Jetson's terminal:
Copysudo modprobe mttcansudo ip link set can0 type can bitrate 500000 loopback onsudo ip link set can0 upcandump can0 &cansend can0 123#abcdabcd

The last command has to have the following output if can is running OK:
Copy can0 123 [4] AB CD AB CD can0 123 [4] AB CD AB CD