Regulations require that all automobile manufacturers establish a common communications system. The communication between the powertrain control module and the off-board diagnostic equipment (scan tool) is achieved on a serial communication line. Serial data is sent in linear form, one bit at a time, over the communication line.
ISO Class 2 Serial Data
This vehicle utilizes the International Organization for Standardization (ISO) communications Class 2 protocol. ISO Class 2 specifies the requirements for setting up the interchange of digital information between the on-board emission-related engine control modules of road vehicles and the OBD II scan tool as specified in J1978. This communication is established to facilitate compliance with California Code of Regulation. The most significant result of this regulation is that the regulation provides the scan tool manufacturers with the capability of accessing data from any make or model vehicle.
A UART serial data line is used to communicate with other modules such as the Electronic Brake Control Module (EBCM) and the Supplemental Inflatable Restraint (SIR) system.
