There must be TWO terminating resistors in the system.

If you're utilizing the 14 pin cable.... you'll need the one on the engine, and ANOTHER plugged into the Junction box.

The terminating resistors indicate the "ends" of the data run, and without them, data will be "garbled".

If you ever need to test terminating resistors- their value is "120 ohms". A CAN 1 data circuit with TWO good terminating resistors will read 60 ohms between the "blue and white CAN 1" data wires.

Install the missing terminating resistor before looking for other problems.