The CAN protocol was originally developed by Intel^TM and Bosch in 1988 for use in the automotive industry to provide a standardized, reliable and cost-effective communications bus for a cars electronics to combat the increasing size of wiring harnesses.

The CAN-bus system is a high speed serial data bus-system linked by an unshielded twisted pair of wires: yellow/black and yellow/brown. The wires are twisted to minimize electromagnetic interference. Both wires carry information and for the CAN-Bus to operate, both signals must be present.

The CAN-system is the fastest of the bus systems used in the MINI, transmitting at 500,000 bits per second. This speed is recognized as the fastest practical operating speed without shielded cable. It is used for systems where the speed of exchange of information is vital for their performance; engine management systems, automatic transmission and automatic stability control.

The CAN-system uses a linear topology which consists of the main bus length and shorter branches. The main bus length terminates at the EMS 2000 and the IKE. The shorter stubs must be as short as possible and no longer than one meter. Any untwisted portion of the bus must not be longer than four centimeters.

Fig 1: CAN-Bus Function

Courtesy of BMW OF NORTH AMERICA, INC.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

System Components: CAN-Bus

Use the Manual With the Right Hardware

When to See a Mechanic