System Description

WARNING: This page is about a different car, the 2014 Subaru BRZ. However, it is still accessible from the selected car via links, so may be relevant.

Summary
1. CAN (Controller Area Network) is a serial communication network for real time applications. It is an on-vehicle multiplex communication line with high data transmission and error detection function.
  
  Fig 1: CAN Communication Diagram
  Courtesy of SUBARU OF AMERICA, INC.
2. CAN communication uses differential voltage signals from a pair of lines: CAN-H and CAN-L (a base voltage is applied to generate potential difference for communication).
3. Many ECMs (sensors) are equipped onto a vehicle and each of them shares information and links with other ECMs (sensors) via CAN communication.
4. The main line has two resistors that are necessary for CAN communication.
Definitions of terms
1. Main line
  1. Harness between the two termination circuits on the bus (communication line).
2. Sub-line
  1. A line branching from the CAN bus main line to an ECM or sensor.
3. Termination circuit
  1. A circuit, composed of resistor and capacitor, converts the line current to bus voltage. Two termination circuits - one at each end of the main bus line are required.
4. CAN J/C
  1. J/C for CAN communication.
Circuit description
1. The circuit is configured based on VBUS. (For circuit connection, refer to CIRCUIT FIGURE )
2. Each termination circuit on CAN bus has a 120 Ωresistor.