[MrE]

My question is "To my knowledge, all I need is the transmission ECU and engine ECU communicating with J1939 CAN bus for it to work". Seeing as I can't use the donor bus as an example because of it's multiplex system, and can't use the Newell as an example because it was all mechanical, is there another component required for the two ECUs to talk? My Range Rover uses CAN bus, and it's probably got about 30 units conversing over the CAN bus talking to each other. If my seat belt isn't fastened it's a CAN bus error, if a taillight is out it's a CAN bus error.

Just want to make sure that I'm not headed back there without something necessary.