NefMoto

Hi guys, not sure if I'm posting in the correct forum here. I'm interested in information on the k-line bus that connects the controllers in my 00 s4. I'd like to know if it's possible in that car to control certain functions of the central locking pump from the bus. I'm mainly interested in knowing if messages to trigger something like rolling down the windows or locking/unlocking the car are even sent on the k-line bus, or is that something that really only occurs in newer can bus vehicles? I thought it would be a cool project to remote control certain functions of the car through an arduino connected to the cellular network. I can think of plenty of cool convenience functions that I could program such as if the car is parked and interior temperature passes a setpoint, and GPS detects that the car is at any of a couple predefined safe locations, the windows and sun roof will automatically crack open to cool down the interior. A rain sensor could close everything up in the event of a storm. I'm pretty sure that the windows and definitely the locks are controlled from the central locking pump, I'd just like to know if it's possible to command the module from the k-line bus, so I wouldn't have to tap into a myriad of different wires to control these functions.

No, not practically. The K-Line and L-Line are single wire serial busses used for diagnostics only. The controllers connected via K and L lines don't have any means of communication between the controllers with any data that would be relevant to the types of interoperability you want. CAN bus controllers do have this kind of functionality. If the '00 S4 uses separate Powertrain, Convenience and Infotainment CAN networks you could extend the CAN with a gateway to connect the three different CAN busses together like on the B6 A4/S4s The 3 separate CAN networks can't be directly connected because they use different data rates.