[valley_nomad]

I have seen "Canbus error free", "Canbus decoder", "Canbus adapter" and other Canbus-related terms that are associated with various LED bulbs. But I have not been able to understand how exactly an LED bulb works with the Canbus which is a networking platform among various electronics modules in the car for digital communication. It seems that neither an LED bulb nor its so-called Canbus decoder/controller/adapter is connected with the Canbus, let alone communicating with other modules via Canbus. Can any one shed some light?

[Billfitz]

Canbus monitors the car systems. If it checks a lamp circuit for the resistance normally presented by a halogen bulb it won't find it with an LED, because LEDs don't present the same resistance that halogens do.

[valley_nomad]

Thanks. But my understanding is that Canbus is just a bus or network connection. It provides only the service for communication among modules and doesn't have any functionality, such as monitoring lamp circuit. In my car it is FEM that controls the front lights, and it very likely monitors them as well... Is Canbus just a marketing term when it comes to aftermarket LED?

[Orion4]

You are correct. The term "Canbus" has just become the overarching term when addressing these issues. As they say" it is just the bearer of bad news".

[Shadycrew31]

Canbus is just a communication protocol vehicles use. The ecu monitors components which are setup to work on a canbus network, light bulbs, ballasts, micro controllers, relays switches etc.

So to answer your question If you install an LED bulb that does not have the correct resistors installed the ECU thinks the bulb is burnt out and will trigger a fault. If the proper resistors are installed in the led bulb the ECU see's everything working normally.