What is CAN (Controller Area Network)?

Controller Area Network (or CAN) is the latest communication system within the automotive world. At its simplest level, it can be thought of as a means of linking all of the electronic systems within a car together to allow them to communicate with each other.

As computerisation within a car increases, so to does the number of different electronic systems. The information recorded and processed by each one is often used by one or more others - hence the requirement for a standardised means of quickly passing information between them. This requirement led to the development of CAN.

Background

The CAN technology was first developed by Bosch for industrial use, but was quickly recognised as a powerful system for in-car use. Some manufacturers were actually using the technology within their cars from as early as 1992, e.g. Mercedes.

Which cars use the CAN protocol for diagnostics?

Within the car diagnostics world, on certain 2003 and newer cars, it is possible to access the CAN network (and communicate with various onboard systems) through the 16-pin OBDII/EOBD diagnostics port. Prior to 2003, manufacturers were required to provide non-CAN interfaces under the OBDII/EOBD legislation, e.g. PWM, ISO etc.

Many of these newer cars, e.g. Ford's latest range, Mazda RX-8, the latest Vauxhall Vectra, offer only the CAN protocol/interface as a means of communicating with the engine-management system. This will actually be mandatory on all cars by 2008.

Whilst many of these cars might still be under the manufacturer warranty, anyone investing in diagnostic tools for the long term should ensure that their tools support the CAN protocol.

The CAN protocol now forms part of the OBDII and EOBD standards. Manufacturers could begin implementing CAN for engine/emissions diagnostic purposes in 2003 and must implement it by 2008.

What are the benefits of CAN-based diagnostics?

The CAN protocols and interface run at roughly fifty times the speed of the earlier OBDII/EOBD protocols. This speed improvement, combined with the addition of new diagnostic parameters, will give technicians the ability to see data faster and gain more information from newer cars than is currently available.

The original OBDII/EOBD protocols (J1850-PWM, J1850-VPW, ISO-9141 and ISO-14230) did help reduce the number of tools required for engine/emissions fault diagnosis, but by allowing 4 protocols there was still a great deal of confusion, and over-complexity of tools.

Simplifying this to a single protocol can only lead to reduce this confusion, and the cost of diagnostic tools.

Which diagnostic port pins are required for CAN?

The CAN system uses pins 6 and 14 in the 16-pin diagnostic socket:

Diagnostic connector

The car will also need to have pins 4 and 5 (ground pins) and pin 16 (12 Volt supply).

Which tools support CAN cars?

Nearly all of the tools we sell now support CAN.
The only exceptions to this are some of the lower-cost manufacturer-specific products, which are designed to cover a specific range of vehicles - such as our VAG KKL cable.

Which cars currently support CAN?

A few examples of 2003/4 model cars that require CAN-enabled tools are:

Ford Fiesta
Ford Focus
Ford Fusion
Ford Mondeo
Mazda 3
Mazda 6
Mazda RX-8
Porsche Cayenne
SAAB 9-3
Vauxhall Vectra

Most new models from all manufacturers from approx. 2004 - CAN must be used for EOBD engine diagnostics by all manufacturers by 2008.

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