openxc-dashboard tool available as a part of the OpenXC Python
library can be used to view the output of the vehicle interface
over USB or UART. This is the most useful tool when determining which vehicle
signals are working.
The Python library can be installed with
Once installed, you can use any of the tools it provides.
It may also be necessary to check the current version of the software you have
on a vehicle interface - the
openxc-control tool can tell you that.
You can also write a message back to the vehicle interface (which may or may not write it through to the CAN bus, depending on if it is an approved signal or not):
You can write raw CAN messages, too: