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What is canbus decoder in the process of upgrading headlights?  Why and how to decode it?

Views:115 Author:hellodido Publish Time: 2022-07-14 Origin:original

With the development and progress of the automotive industry, more and more cars are equipped with driving computers and driving protocols. When we upgrade xenon lights or LED lights, or even replace the width lights or brake light, the dashboard will appear "fault lights"(error messages on instrument panel), or one side or both sides lights off, flashing problems etc. 

The above situation shows that this car need to canbus decode when transforming car lights.

error message on instrument panel picture


This is because the power of halogen bulb is generally 55W, while xenon lamp or LED lamp is usually 30W to 40W. When the power is reduced, the current becomes smaller. 

So when the driving computer detects that the current is different from the original, it judges that the headlamp is faulty, thus error messages will appear on instrument panel.  

Therefore, when upgrading xenon lamp or LED lamp, we need to decode in order to solve the fault or interference problem.

So how to decode it?  What are the common decoding methods?  

1. Use the LED headlight or HID xenon which have the canbus function itself.

The LED headlight or HID xenon ballast has a build in canbus system and no need to add some other methods, just plug and play, this method is most popular.

For the LED headlight, we suggest F55 canbus LED headlight, it has strong canbus function and can pass 90% of the  cars on market.

For the HID xenon ballast, Q5 canbus ballast can pass most of the car on the market and no error lights on instrument panel.

2. Capacitor decoding  

Connect a capacitor to the positive and negative ends of the power cable.  

capacitor decod image

The detection of light bulbs by capacitive absorption filter train computer.  Capacitors of 22,000 uF and 4700uF are usually used according to the size of the detection signal output by the vehicle computer.  

This method is mainly for pulse detection and waveform detection models.


3. Resistance decoding  

Resistance image

A common approach to cars is Ohm's law,  

R =U (voltage) /I (current)  

For example, after the car starts, the voltage is 14V, the halogen bulb current is 5A, and the resistance is 2.8 Ω.  The disadvantage of this decoding method is the resistance heat while the advantage is fast in decoding speed.  

4. Modify the CAN protocol, also known as computer software code  

computer canbus image

This method is mainly for Volkswagen, Skoda, Audi, BMW, Ford, Benz and other models.  Use the car manufacturer's engineer computer to change the car code, achieve decoding.  This decoding method is the most scientific, use the engineer computer to turn on xenon lamp or LED lamp function and turn off halogen lamp function.  

4. Relay harness decoding.  

relay harness image

This method is mainly used for Korean cars.  The bulb flicker due to excessive starting current of left and right bulbs after installing ballast.  The decoding can be achieved by balancing the current on both sides with a combination of lines. 


So the above are some common decoding methods, if you have canbus decode problem or need any technical support, contact us at [email protected]

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