Hello, I read the documents and learned more on CAN BUS communication. It's really interesting and it made me understand strange things that can happen in the car.
1. According to the priority messaging system, when a problem occurs (not serious but triggers the engine alert), we have an engine alert on the dashboard and just after a second related alert from another controller. Not really important, but it is better to know why it is done this way.
2. Along the coding of the controllers, I saw that certain parts or sensors which were actually implemented on the car were recorded as "not mounted" or "not installed, not coded" on certain modules. Depending on the vehicle's equipment, the elements are connected directly to the controllers or to the onboard network BUS. Sometimes, the sensor is used for several units but when it's used for only one unit, there's no reason to make it communicate with all modules. So, VW made sub-networks or direct connections. Some modules'firmwares allows the two options which can be coded. In the Passat, it's the case for rain sensor and many others. I.e., we only select communication mode with those components. If it's coded on the module, identification and priority module's code is recognized on the bus can and data can be shared.
I know now why wires are interlaced (to avoid magnetic perturbations) + the two wire doesn't have the same working voltage but signal shapes are similar or opposite to limit inducted magnetic fields.
But in my car, near coupling points wires aren't interlaced on several centimeters (factory fitting) and there's no trouble... Is this allowed by self error control through comparing the two wires signal???
Beside this, I read other on Passat and diagrams to find the best way to connect driver seat controller. It's on harness just before door's coupling point on confort CAN Bus. It seems to be easy and nearly conform to factory fitting diagram.
I didn't find anything about the best way to connect CAN wires to other ones.
Thanks for all informations, comments or documentation :