CANbus is the work of the devil when applied to whole vehicle - it means instead of just fitting a new part you have to address it and get it to talk to the network. Each module (eg. rear light cluster ) can receive and send information back to ECU (to tell if a bulb has blown etc. but to do this it measures the current device is drawing, if you replace a normal filament bulb with an LED one which will draw much less power it will signal a fault) - there are two ways to get new bulb accepted - one of which is to strap a resistor in parallel with LED to draw enough current to fool the module, another one is you can reprogram (or get it reprogrammed) the system to accept the new lower current. That is why a lot of aftermarket equipment like LED bulbs and HID bulb power supplies are labelled 'CABbus compatible' as they will fool the system, also CANbus systems can be more susceptible to electrical interference than normal wiring system so an un-suppressed shonky after-market HID module (25KV) will play havoc with the bus, but on a non-CANbus system will just interfere with your radio. Most Jap car makers have been slow to go over to CANbus to control every aspect of the vehicle, but the Europeans went into it headfirst. This lines up well with the fact that Germans were put on the planet to make things as complicated as possible, but the Japanese like to keep things simple - anyone who has ever worked on Siemens industrial stuff will know where I am coming from, Allen-Bradley, Omron and Mitsubishi are much more user friendly.
https://en.wikipedia.org/wiki/CAN_bus