Electronic Control Modules - Service Information: Communication: Operation

Data exchange between modules is achieved by serial transmission of encoded data over a broadcast network. The Controller Area Network (CAN) data bus messages are carried over the bus in the form of variable pulse width modulated signals. The engine CAN data bus speed is 125 Kilo-bits per second (Kbps) (ignition on) while the interior CAN data bus speed is 83 Kilo-bits per second (Kbps).

The voltage network used to transmit messages requires biasing and termination. Each module on the CAN data bus system provides its own biasing and termination. Each module terminates the bus through a terminating resistor and a terminating capacitor. The Powertrain Control Module is the dominant node for the CAN engine data bus system and the Body Control Module is the dominant node for the CAN interior data bus system.

The CAN bus uses low and high voltage levels to generate signals. The voltage on the bus varies between zero and two and one-half volts. The low and high voltage levels are generated by means of variable-pulse width modulation to form signals of varying length.

When a module is transmitting on the bus, it is reading the bus at the same time to ensure message integrity.