Using LED with a CAN Bus System

You have heard once before, and you will hear it again.  “What is a CAN bus system?”  A CAN bus is a “Controller Area Network” vehicle bus which interconnects components inside a vehicle.  A CAN bus is like an on board diagnostics system that runs upon turning the ignition and while the vehicle’s operating.  The system also monitors your vehicles applications such as lighting.  A CAN Bus system is equipped with the vehicle to alert a driver of a problem with the normal functionality of an application or their vehicle.  A lot of 3rd parties indicate that it only monitors your lighting applications, which they do, but they also monitor everything else that may be considered a safety hazard should the part, component, or application fail or begin to malfunction in a manner that is considered abnormal.  A CAN bus system can be frustrating or cause malfunctions but they are an essential system to have on your vehicle.  We created this article to help you understand how to make your lamps function properly without a worry of a dreadful lamp out indicator or flicker.

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The main reason why a CAN bus system cannot detect an LED bulb is due to the power draw (current) of the lamp application or resistance change.  By upgrading your lighting application, whether interior or exterior, you are decreasing the power draw substantially.  It may vary between vehicles, but a CAN bus system (or any similar system) is designed to function a certain amount of power (current), voltage, resistance or amperage of the different applications on the vehicle including lights and by installing an LED bulb, it may recognize the bulb as a fault or opened circuit.(burnt out bulb)  These type of systems are not designed to work with the current of an LED replacement.  They will not be able to distinguish the difference between an actual ‘burnt out’ halogen bulb, and a new upgraded LED so an error code or lamp out indicator may be triggered.  Some cases it will cut power to the application which will result in a sudden flicker then shutting off.  So how do you solve or avoid this malfunction?

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The solution is very simple, for most vehicles.  JDM Astar offers “error-free” LED replacements in various sizes from 921 (T15), 1156 bayonet size, and all the way to bulb sizes for headlamps.  They come equipped with built-in decoders.  A decoder (or anti-flicker harness) is a module that is designed to counter or fix CAN bus related problems and they feature a built-in capacitor to keep the LED’s charged (prevents flickering).  The decoder will also increase amperage which will allow the system to detect the lamp (prevents lamp out indicator).  There is also added resistance to allow the vehicle’s circuit normal functionality and ensure the LED’s are receiving proper current.

You can also take the simple route and add resistors which will allow the bulb to simulate a much larger current draw which for most cars will fix a problem triggered by the system.

Another great option is to use an “Error Free” LED which for the most part is designed for vehicles equipped with CAN bus.  With Error Free LED’s, they will feature resistors within the bulbs circuit to allow a larger current draw, however, this type of setup has its limitations on how much can be drawn.  There are certain makers and/or model vehicles that are programmed to detect a much larger current than what a CAN bus-ready LED bulb has to offer.  They may still trigger an error code so then the proper load must be applied to the vehicles circuit by wiring in a resistor.  You can do this by installing resistors to the ground and lead wires.  Resistors will draw out the difference in power to simulate the power draw of your halogen bulb.

If your vehicle is built with a CAN bus system, then don’t worry.  We have an arsenal of solutions waiting for you to resolve any minor issue with your vehicle’s CAN bus system and LED replacements.  If you run into a problem, we are here to help.  We can help you find the perfect LED replacement so that you will have an error-free experience.

-JDM Astar Team