Originally developed by Bosch in the 1980s, CAN (Control Area Network) is a robust system which enables high-speed communications and signals between different systems on a vehicle without the need for complex wiring. An increasing number of manufacturers utilise CAN Bus for managing systems such as lighting, heating, instrumentation, suspension, braking and engine control with separate ECUs which can be linked with a single pair of wires, thus drastically cutting down the total amount of wiring required within a vehicle.

This allows the different ECUs to work together effectively and efficiently. The engine reports the vehicle’s speed to the transmission, for example, which in turn must tell the gearbox when to shift up or down. Using a CAN system allows vehicle manufacturers to build in additional equipment but reduces the overall weight of the installation. It allows for simplified electrics, therefore addressing issues with specific areas of the vehicle or individual component systems becomes more straightforward as each can be isolated and diagnosed via the OBD port.

The CAN messaging system consists of ‘CAN Frames’ containing bits of data associated with the various inputs that a system or component requires to operate. A basic ‘CAN frame’ contains 11 bits of data, more complex, extended systems can contain up to 29 bits of data. The data transmitted between ECUs can trigger commands, confirm activation and report errors , amongst a host of other two-way interactions.

So why does CAN matter when fitting Auxiliary Lighting?

When switching on a vehicle’s standard headlamps the unit historically received a basic 12V signal to operate, it was either on or off. With CAN, this 12V signal is replaced by a different type of signal, in the form of a CAN frame mentioned above. Auxiliary LED lights cannot always interpret this signal correctly and it could cause the auxiliary lights to flash rapidly or not activate at all.

How do I know if I need a CanM8 High Beam Interface?

Just because your vehicle has a CAN Bus system doesn’t necessarily mean you’ll run into any problems. Some vehicles using CAN still send a 12V signal to the headlamps when the High Beam activates. If this 12V signal is available, it will activate the 12V relay in our wiring kits and the lamps will work as normal.

VIDEO: How to Locate 12V High Beam Signal Wire

NB: It is important when testing the strength of the signal to the back of the headlamps that you identify the correct wire/pin for the high beam and check the signal strength on/off by having another person flash the lights, not by leaving the high beam in the permanently on/off position.

If the strength of the signal to the high beam is less than 12V then a CAN Bus interface to interpret the CAN frame will be required. The Lazer CAN bus Interface, developed in partnership with UK manufacturer CanM8, provides an effective solution for detecting both High Beam and Side/Position Light activation.

Each interface is supplied with a dedicated wiring kit for simplified installation, as well as compatibility with our Contactless Reader (see below). The interface incorporates a multi-function status LED, which indicates correct connection to the CAN system, CAN activity present and confirmation that the CAN identity has been recognised.

How and where do I fit the CanM8 High-beam Interface?

Your local franchise dealership or qualified auto-electrician should be able to advise you on the location of the CAN module, the relevant coloured wires from the CAN and specifically which wires relate to CAN Hi and CAN Lo. Purchase of the Lazer CAN bus Interface will also permit access to vehicle specific installation guides, via the CanM8 app. You are of course welcome to enquire with us directly, or through CanM8.

VIDEO: CAN Interface & Wiring Kits

Will fitting the CAN interface void the manufacturer’s warranty?

During the installation process, care needs to be taken as you will be connecting wires directly on to important vehicle systems. The vehicle warranty will be unaffected, so long as the installation has been carried out correctly, without damaging the surrounding systems. If you are unsure, get the help of a qualified auto electrician.

NB: Always make sure you strip and connect one wire at a time. Do not strip both wires before connecting the CanM8. If the Can-Hi and Can-Lo wires touch it can cause significant damage to the ECU.

An alternative, non-invasive option is the CanM8 Contactless Reader which allows the CAN Bus interface to read vehicle CAN Bus data without any actual metal to metal connection. The reader is secured around a section of the vehicle CAN Bus wiring and data is read simply by induction.

The CanM8 RUI (Research and Update Interface)

Each Lazer Can interface kit is supplied with the latest firmware at the time of manufacture. However there are times when a new or updated vehicle has not been added to the CanM8 database or the CAN data is not being interpreted correctly by the interface to operate the auxiliary LED lights as expected.

This is not a limitation of the system, often manufacturers will update the headlights and associated CAN during a facelift, for instance, or a new variation of an existing model is released with a slightly different CAN signal. Fortunately the Lazer Can Bus units are upgradeable and can be remotely updated with the latest CanM8 firmware to accommodate the latest specifications.

In these instances it will require the use of an CanM8 RUI (Research and Update Interface), which is available to trade customers direct from CanM8 or via Lazer. The RUI kit and associated smartphone app has a dual function: It can be used to update the CAN Bus firmware and also interface with the vehicle’s CAN to analyse the relevant data, allowing CanM8 to update the module with the relevant data to deal with a specific vehicle.

Remote analysis will require a live connection with the CanM8 engineers (via the smartphone app) to read and interpret the CAN data. New firmware will be issued which can then be updated on the module to be fitted to the vehicle. This process can take from a few minutes to a few days depending on how long it takes for the firmware to be updated so it is always worth contacting CanM8 directly to discuss the issues in advance.

When you purchase a CanM8 RUI kit, you will be issued with a username and password which allows you to install and use the supplied Windows software onto one desktop PC and one Smartphone App (available from Google Play or the Apple App store). Registered users will then have access to the library of vehicle specific installation instructions, showing CAN Bus locations and detailed wiring information for installations of the Lazer CAN interface modules.

If you are working on a vehicle which is not listed and need to arrange a live session, this can be arranged direct with CanM8.

VIDEO: Using CanM8 RUI to update install for a Yaris GR.