[zyNoT]

You need to set your multiplexing settings on engine ECM to point to the cab controller.
You can find these settings in INSITE > Features and Parameters > Multiplexing.

49 is correct, make sure that the correct CAN channels & baud rates are set.
Newer ECM's use CAN4 while older ones do not. The baud rate is also set different.

There are also parameters set in the calibration that are specific to J1939 communication. 
Each calibration likely has different ones set for different chassis.