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Light Failure Warning Light After LED Kit Installation | Bypass CANbus

Posted on: 2025-01-11
Lights failure warning lightsu Quandro strumenti Auto

CANBUS SYSTEM

 

Before trying to circumvent it, you need to understand what the Canbus system is and how it works.

Trying to summarize it in a very few words, CANbus Technology allows you to have an intelligent electrical system on the vehicle, capable of detecting the parameters provided by the manufacturer and communicating with the on-board computer instantly.

PROBLEMS AFTER INSTALLING LED BULBS

Depending on the type of car CANbus and the LED bulbs or full LED kits installed, you may encounter various types of problems:

  • Light Failure Indicator
  • Turning the lights on and off
  • Flashing lights
  • Radio Interference and Flickering
  • Reduced lighting power
  • Non-functioning or reversed operation of the high beams (in H4 models)

Some of these phenomena could occur together, but the solution and resolution may be different from case to case, as you may need ARMORED RESISTORS or ADDITIONAL FILTERS, it is useless to confirm that everything can be prevented from the start by 90% by purchasing correct and reliable LED lighting. Quality, the remaining 10% are cars with a particularly restrictive CANbus technology.

WHY THEY OCCUR

The problems listed above are due to the fact that the CANbus system of the car in question detects parameters different from those provided by the parent company which are not respected after the installation of an LED light transformation kit.

A Direct Example in a Simple Way:

A Halogen Car Bulb Has a Wattage / Absorption of approximately 55W per lamp;

On average, a Professional LED bulb has an assortment of 22W (LED is famous for this: Low Consumption, High Light Yield);

.

So the CANbus System Intelligently Detects That Its Halogen Lamp Is Not Working Correctly Or Is Burnt For This Reason It Reports The Light Failure, Or In The Case Of Flashing Or Failure To Turn On It Cuts Off The Voltage To The Headlight As A Precaution And Safety, To Then Try To Send It Again after a few moments, but detecting the problem again stops it again, thus creating a strobe or flashing effect.

Halogen and LED bulbs compared

HOW TO NOT HAVE CANBUS PROBLEMS

To Evade the CDB (On-Board Computer) It is Necessary to Install a Full LED Kit or LED Bulbs That Have the Same Absorption "W" and Voltage "DCI" as the Halogen Bulb. This is Possible with Only Professional and Specific LED Kits Assigned According to the Vehicle.

Representation of CAnbus Car Chip ECU
Calculation of Watts and OHMs

Cars with more restrictive Canbus:

Clarified that basically the problem lies in the different "Watt" absorption between the halogen and the LED, (which for the halogen bulb could mean greater light power, but for the LED, we can say for now that it is only the consumption)

There are cases in which it is more difficult to evade the CANbus, these are RESTRICTIVE CANBUS, i.e. Canbuses that are more attentive to the minimum variance in Watt "W" but in this case also in "DCI" voltage, to reveal the sensitivities:

A slightly restrictive CANbus that has a basic parameter of 55W halogen bulb, if you install a 49W LED bulb it is very likely that no problems will arise.

A Restrictive CANbus that has a 55W Halogen Bulb Base Parameter, if you install a 50W LED Bulb, it is very likely that the Annoying Light Failure Warning Light will appear.

I BOUGHT A 50, 60, 70, 80, 90, 100 WATT LED KIT BUT I HAVE PROBLEMS:

If you have purchased an LED kit where they tell you that the Watts are 50 or higher, "if true" you simply should not have any type of problem, otherwise an incorrect marketing action has been taken to sell more.

REMEMBER, LED Wattage Does Not Mean More Light Power, Don't Be Fooled.

See the QSPCARS Professional LED Kits

THE BEST CHOICE - LET'S SOLVE THE PROBLEM

Given that the best choice is to purchase a full LED kit or professional LED bulbs that are CANbus, i.e. they already have built-in dynamic filters, which is why they are also the most expensive. 

But if you are reading this little guide it is probably too late, so let's try to solve the problem:

As mentioned at the beginning, there are various cases and each one must be calculated and resolved in its own way. Forcing and testing in this phase can only lead to the lamps burning.

First of all you need to understand if you need additional filters or armored resistors.

WHEN ADDITIONAL FILTERS

Filter Turn Off Warning Light H7 Car Light Error

By avoiding technical explanations, we aim to help you understand how to choose the correct accessory.

The use of the same, as per the name "Filters", are used to Filter the Electrical Voltage between the Car and the Light Bulb. They are composed of capacitors (capacitors) that store voltage, and here the value to keep in mind are the MicroFarads "units of measurement of electrical capacity", their use is to be attributed to the least problematic cases, such as:

  • Lights flashing but regular operation without warning lights
  •  Occasional error CDB
  •  Radio interference
  •  The lights do not operate regularly (low beam or high beam reversed) or flickering
  •  Poor Lighting Power (not to be confused with an incorrect choice of LED Kit)

In conclusion, additional filters should be used:

Where the problem is not very accentuated, their quality can be attributed to the MicroFarads. If you want to rely on us, click here and view the best filters for H7, H4 and H1 LED kits.

WHEN RESISTANCE ARMORED TANKS

Unfortunately their value must be calculated for each car depending on the bulbs installed or to be installed. We will teach you how to do it and choose the best armored resistors. Their use is linked to more complex situations, where the problems occur together or are more accentuated. , How:

  •  Error on the CDB Fixed when turning on the lights
  •  Flashing lights
  •  Failure to turn on



Resistor H7 Turn Off Error Warning Light Car LED Lights

To choose the armored resistances you will need to calculate:

  • OHM (Value of Necessary Resistance )
  • WATT (Value to Dissipate)

They can be handcrafted (perhaps good news for you), but we strongly advise against this process, and indeed we invite you to purchase the best armored resistors you can find, since the quality of the materials plays an important role on this accessory, which It heats according to the electrical energy and the wattage that it must compensate to make the CDB believe that the lamp you have installed has a Absorption equal to the old halogen.

The Elements that Make this Article Quality are:

  • Heat shrinkable sheath
  • Metals and Heat Conduction and Dispersion Materials
  • Nylon Coated Wire

Attention, the Laws of Commerce often dictate that the lowest price sells the most, therefore we confirm that unfortunately 80% of those on the market do not have any of the 3 points indicated, and are undersized thus reaching temperatures that exceed 100°. If you want to trust to Us Click here and View Availability for H7 LED Kit.

CALCULATION PRACTICE OF LED RESISTORS

Let's start by calculating the WATT value to be dissipated, making a subtraction between Watts of the halogen lamp and Watts of the LED lamp, the result (the difference between Watts) will be the value to be dissipated in Watts. Be careful to avoid excessive overheating and double this value. For Greater Quality, the calculations Made by QualitySpCars when supplying this Item are Based on Triple This Value.

The true calculation of the resistance lies in the OHM and must be done by squaring the voltage of the vehicle with the engine running (V) and dividing it by the difference in wattage consumption between the original bulb and the LED lamp to be installed.

Representation of mathematical calculations

PRACTICAL EXAMPLE OF CALCULATION OF CAR LED RESISTANCE - FORMULA

Audi A4 b7 With LED Headlights On
Audi A4 B7 Light Failure Error | Example Calculation of Resistances

Don't you understand? Or Do you want to understand how to do it practically? 

Don't Worry Let's Take an Example Case AUTO+ LED Kit and Calculate the Exact CANbus Resistance:

- Car: Audi A4 B7, Known For Its Restrictive CANbus, The Annoying Light Failure Warning Light Easily Appears After Installing LED Kits On Low Beams And High Beams

- Professional LED Kit: QSPCARS Copper Mesh LEDs, One of the Best LED Kits on the Market.

See the QSPCARS Professional LED Kits

Values to Know for These 2 Calculation Elements

  • Car voltage with engine running: 14V
  • Watts of the original low beam and high beam lamps: 55W
  • Watts of the 5S Plus LED Kit: 45W

 

Practical Canbus Resistance Calculations:

Square of Car Voltage with Engine Running: 14Vx14V= 196V

Consumption difference between halogen lamp and LED lamp: 55W-45W= 10W (to be doubled or tripled for optimal resistance)

OHM Calculation "Divide the Square of the Voltage by the difference in Watt Consumption: 196V:10W= 19.6 "So we will need a 20 OHM 30 WATT resistor" 

Hoping to have been as helpful as possible. You can rely on us, Click Here to view the accessories that QualitySpCars has available for the installation of LED and Xenon kits.

We also invite you to try our SEARCH SYSTEM FOR YOUR CAR where we have reserved an area for each car, where accessories and LEDs are tested for compatibility.



SEARCH FOR YOUR CAR
Posted in: QSPCARS BLOG

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