Harley-Davidson's Can-Bus communications system: HDLAN

In this article, we'll try to explain in a simple way Harley-Davidson's latest communications system, the HDLAN.
This new technology will allow the entire HD range to feature ABS brakes, reduced wiring, and the elimination of the ignition key, among other improvements.

Internet inside your motorcycle
One of the first questions you might ask when you hear about the communications system is, "Why does a motorcycle need this?" The answer lies in the technological evolution that automotive brands have been forced to undertake in recent years to reduce emissions and comply with increasingly stringent regulations, while simultaneously improving safety and ride quality standards.
With the adoption of electronic injection, it is necessary for the various sensors and actuators to communicate with the vehicle's ECM or control unit.
This communication occurs in digital language, that is, with "zeros and ones," just like our personal computer or tablet.

Let's give a simple example:
-The pilot activates the left turn signal switch.
-The handlebar button module sends the message “flashing button actuated” to the network.
-The BCM (electrical controller) reads this message and energizes the turn signals on the indicated side, it also looks for the speedometer signal and also the tilt sensor signal, in this way it determines how long the turn signal will remain on.
-At the same time, the speedometer also reads the message and turns on the dashboard indicator light.
All these messages are sent through a cable called the “Data Bus,” which is a kind of Internet within the motorcycle, allowing the modules to communicate with each other.

HDLAN
Until 2011, the communications protocol used a single wire and was based on the J1850 standard. Starting that year, a faster, two-wire communications protocol, HDLAN, based on the CAN BUS automotive standard, was introduced in the Softail models and later in the Dyna family.

To avoid getting lost in technical details, imagine that J1850 is like the old, very slow PSTN-based telephone line internet. CAN BUS, on the other hand, would be like ADSL, faster and more modern.

Using the HDLAN (Harley-Davidson Local Area Network) communications system offers several advantages:
-Higher data speed
-Greater security against data loss
-Minimizing the wiring, relays and fuses on the motorcycle

-More compact and unified modules
-Improved diagnostic capabilities

The heart of the system is the BCM, a module that directly receives power from the battery.

In models prior to this system, if we pressed the horn button, for example, we connected the battery power to the horn so it would sound. The electricity ran from the battery to the handlebar button, traveling all the way around the bike, and then back down from the button to the horn.
With HDLAN, when we press this button, what happens is that it is "published on the motorcycle's Internet" that we want the horn to sound, so the BCM reads the message and sends electricity directly to the horn so that it sounds.

There's no more electricity running up and down the handlebars to activate it, just a message. This, applied to the entire motorcycle electrical system, means all modules (speedometer, ABS, BCM, ECM, radio, etc.) can communicate with each other, resulting in superior performance and reliability.

Improvements like those that have appeared in the Sportster models, such as the ability to display the engine speed or the current gear on the odometer, the introduction of ABS, the elimination of the ignition key, and the optimization of the battery compartment, are all possible thanks to this technology.

Conclusion
It's clear that custom model owners aren't the biggest fans of technological sophistication, but knowing that it will inevitably engulf our lives (and our motorcycles), at least it's comforting to know that in some cases it's used to simplify complex systems, making them safer and more reliable at the same time. The result is that magical blend of old school and new technologies that will keep us riding freely and better connected.

Frank Burguera

#harleymechanics