So with the release of this bike, there has been a ton of questions about CanBus. What does it control? What does it not control?
What is CAN? CAN stands for Controller Area Network. CAN was designed in the 1980s because of limitations of existing serial buses for use in cars. You can dive in more about CAN history in this article: History of CAN technology
Honda is kinda late in the CAN game. BMW has been the powerhouse for years in the use of CAN. Indian uses it extensively and Harley started in 2011 on the Softails and 2014 on the Ultras.
On the physical layer, CAN consists of two dedicated wires for communication. These wires are called CAN high (red wires in above picture) and CAN low (white wires). These 2 wires are connected to and create all the communication between all the CAN controlled Units on the motorcycle.
The main brain of this system is the “Smart Control Unit”, but other modules work in conjunction with it. These include the TCM (Traction Control Module), ECM (Engine Control Module), and the Front and Rear Control Units (among many others, but that will be our focus).
The Front Control Unit does more tasks than the rear. It takes data from CAN high and low and controls everything from the heated grips to the headlights. It also takes the inputs from the handlebar controls for various functions. The switches use varied amounts of resistance for each function so that the Control Module knows what function you are trying to control. The Rear Control Unit does the seat heat, suspension adjustments and some other, but mostly those 2. Most traditional CAN systems remove fuses and relays, but the new Goldwing does retain some. Our initial view of the Honda CAN system shows the Front & Rear Control Units are fully responsible for supplying power for some functions, but others have their own fuses. This does not mean you should tap into those circuits that do have fuses as the Control Units still have inputs from those wires; this means they are monitoring them at some level.
In a traditional CAN system without fuses, the CAN knows that a certain circuit will have a minimum and a maximum amount of current set in the threshold. Too much current draw and the CAN will think there is a short and shut off. Not enough and the CAN will think whatever it’s trying to operate isn’t working. Most cases either of these can cause the CAN to shut off as a method of protection and in some cases will display a fault code on the dash.
Ok…so I know what are you asking at this point. Can I just tap into the existing wires like we used to? Probably not. I’ve not been able to fully research all the ins and outs of this system. Especially with the circuits that have fuses. If you do tap into it, and you hit the wrong wire, or you were to apply more load than the computer wants to see, there is a chance the bike will shut off that circuit until you get the bike to Honda and have the CAN examined. And as of my writing, dealers do not yet have the tools to do so. This could lead to problems with warranty as CAN wires do not like to be disturbed.