Can someone please give me a brief overview of potential challenges or pitfalls of creating an aftermarket add-on CAN bus device for Toyota and/or Chrysler vehicles? I'm well versed in software and reasonably good with hardware, but new to CAN bus, and specifically CAN bus in the automotive environment. My goal is to make a device that plugs in as just another node on the CAN network, and can communicate on the network to detect and toggle the state (on/off) of select buttons on the dash board.