How Do I Get Rid of Canbus Error While Installing Led Lights in Car?

car lighting

The CANBUS is a technological standard born in the early 2000s and used by almost all cars today. It serves among various functions to detect any light bulbs burned out completely automatically. On a CANBUS car, when a light bulb is burnt, the car itself will notice them and indicate it to you with a message on the dashboard.

When you replace an original incandescent bulb with a led bulb, the car may not be able to recognize it and immediately signal the message on the dashboard. It seems like a kind of message like “error !!”

A CANBUS led bulb has electronics that can be recognized by CANBUS cars; in this way, you will not have any error message or lights failure on the dashboard. It is Indispensable for cars produced in the last ten years! So you can mount these led lights without worrying because car CANBUS will recognize them without reporting anomalies.

You have chosen the right LED bulb for you, but you have found yourself fighting with the CANBUS system. When you change the bulbs and install the 3157 LED bulb in your brake light, you can have problems with the Canbus.

car lighting

The Reason Why Some Led Lights Don’t Work with Canbus

The led lights do not work with the Canbus because the led bulbs draw less current, and therefore the control unit reads a lower working power from the bulb and responds error to the Canbus system. The control unit turns on the burnt-out headlight or even stops sending power by switching off the component: this is for safety reasons.

Getting around this problem is simple, usually just putting resistance in the circuit. But given that there are many types of LED bulbs, to be sure of the result, you need to have a tester, patience and take measurements.

car lighting
How to Measure and Calculate

I will show you the steps that I followed to get the resistance to buy so that any bulb you will replace ( low beam, high beam, stop, or position with a 921 led bulb), you can always find the resistance that is right for you.

Let’s start by measuring the current that the original bulb needs, which we will replace with the led. To measure amps, connect the tester in series to the bulb and turn it on, better make these measurements with the car on.

The same procedure must do with the led bulb. Since you are there, also check the voltage, which must be measured by putting the tester in parallel.

Do all these measurements with the engine running and maybe with the high idle (2000 – 3000 rpm) because the voltage varies, and it is easy to have much more than the classic 12 volts. Very often, at high rpm, it even reaches 14.5 volts.

Now you have all the data you need, let’s do the calculations. We calculate the watts of the led bulbs and the original bulbs (do not trust much what write on the bulb, it is always better to do the calculations with the instrumental data) So now, we can trace the resistance of the two circuits: LED circuit and filament circuit.

And we can finally go back to the resistance that we will have to buy, which is what we need is to mount in our specific case without making several attempts, therefore straight to the goal!

When you mount resistors that dissipate a lot of currents, you will have to take them well-placed. It is better to place the resistors on the metal place but not plastic.

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