If you don’t know the CAN message of the steering wheel control button, you need to find it.
When the Scan started, numerous CAN message will be listed in the CAN mesage list.

The steering wheel control message has its own CAN ID or IDs. We need to see only the steering wheel control CAN ID.
Click ID Filter to seel the ID Filter dialog. All the scanned CAN IDs are listed in the ID Filter list.

When you push the steering wheel button repeatedly, a new ID will appear at the end of the ID filter list.
This is the steering wheel control’s CAN ID.

To filter out the the CAN message with the steering wheel control’s CAN ID, enable the HW Filter.
Check the box Enable CAN ID HW Filter and HW of the steering wheel control’s CAN ID.
Then CPJexc received only the CAN message of the steering wheel control.
Because there is too many CAN messages to receive all the CAN messages on the CAN BUS,
leave the HW Filter enabled after the scanning is finished.