Sunday, Jun 02, 2019 at 11:33
The CAN bus system was developed by Robert Bosch in 1983 and presented to manufacturers in 1986.
It was developed due to a need to control the new electronic fuel injection systems produced from 1986, and to more accurately control exhaust emission levels.
CAN stands for Controller Area Network, and the word "bus" in electronics is simply the contraction of "omnibus", thus indicating an electrical pathway for electronic communication purposes.
The CAN bus system allows electronic communication between ECU's/ECM's, microprocessors, and sensors, without a dedicated host computer.
The CAN bus communication system began to be fitted in vehicles from 1991, in Mercedes cars.
The CAN bus system was then "enlarged" to allow connection of code readers/scanners, to enable OBD - On-Board Diagnostics.
In 1993, the CAN bus system was recognised with an International Standard - ISO 11898.
In 1991, the California Air Resources Board (CARB) declared that all new vehicles sold in California needed to be fitted with some type of OBD device to enable diagnostic control of exhaust emissions.
The CARB regulations took until 1994 to be defined precisely, and legislation made it mandatory for OBD to be fitted to all cars and light commercials from the 1996 model year in California.
OBD was fitted to a large percentage of vehicles sold globally from 1996, with more makes and models being added yearly, as more electronic controls were added to the vehicle construction.
1996 saw the standardisation of fault codes across all vehicle CAN bus systems.
Prior to 1996, manufacturers used their own fault codes with no standardisation, thus creating diagnostic difficulties.
The standardised OBD system from 1996 is known as OBD-II. Any diagnostic system in use before 1996 is known as OBD-I or sometimes just OBD. The OBD-1 systems are extremely basic and limited.
There is no car or light commercial built in about the last 18-20 years that does not use a CAN bus system with OBD-II.
Your electrical ECU's in your vehicle are programmed via factory software to control electrical loads and electronic signals, with electronic and electrical parameters.
If the signal is outside the set parameters, the system will log a fault, or simply refuse to operate - or go into "limp mode", operating under low levels of power with limited operation.
This is done as a protective measure to prevent overload or damage to components.
Cheers, Ron.
FollowupID:
899575