eZ Navi Delete Project

radensb

Different languages and physical layers.

Pins 4 and 5 on the M67 are a completely different voltage signal and protocol than M72 pins 6 and 8. The dial module with M67 uses a RX and TX style of communication with a voltage reference lifted from ground (for noise immunity I imagine). This communication is directly with the AC Amp in base model cars.

The Navi stock controls on M72 operate on a secondary CAN bus (AV-Comm) with the Navi controls and touch screen interface. The Navi head unit has a CAN Bus hub that links the AV-Comm CAN bus with the main ECU CAN bus which is what the Navi based AC Amp (white box under head unit) is connected too. One set of CAN messages live on the AV-Comm CAN bus where certain ones that contain information about the state of the AC controls are translated into messages on the main ECU CAN Bus. This was needed to get the information about the AC system to the head unit so that it could be displayed for the user on the screen.