How to Choose the Right Wiring for Your Lighting

Step 1: Understand Why a Relay Cable Kit is a Must

Let's start by saying that trying to connect auxiliary lighting without a proper relay cable set is dangerous and wrong. The car's original wiring to the main beam is extremely thin and designed to handle a lamp of about 55W. Loading them with a 150W LED ramp will lead to overheating and fire risk.

A relay cable kit solves this by an ingenious principle: It draws the power (high current) directly from the battery via a thick, fused cable. It uses only a small signal current (low current) from the car's high beam to activate a switch (the relay). When the relay receives the signal, it switches on the power from the battery to your new lights.

This protects the car's electrical system, ensures that the lights receive enough power to shine at their maximum, and is the basis for a safe and durable installation.

Step 2: The Big Choice: Modern Car with CANBUS or Older Car?

This is by far the most important decision you will have to make, and it depends entirely on your car.

Track 1: The Modern Car (circa 2017 onwards) with LED/Xenon headlights

If your car has advanced headlights and a modern electrical system, your lights are controlled digitally via your car's computer. This is called CANBUS. Here, there is no simple +12V cable to "steal" the signal from. Trying to find one with a multimeter is futile and risky.

The only safe and recommended solution is a CANBUS interface like the XBB Dongle.

How does it work? You connect a small box (Dongle) to your car's diagnostic socket (OBD-II). It reads the car's digital signals and wirelessly sends the "high beam is on" information to a small receiver (PowerUnit) to which you connect your relay cable set.

See XBB Dongle: https://xenonkungen.com/produkt/xbb-obd-ii-dongel-powerunit/ 

Why is it the best? Simply because it is 100% safe. You won't damage your car's original wiring, you won't risk any fault codes, and it's an incredibly smooth and quick installation.

Track 2: The Older Car (before about 2016) with Halogen headlights

If your car has traditional halogen bulbs as high beams, it usually has a simpler electrical system. In this case, you can use a traditional relay cable kit and get the high beam signal directly from the cable to one of the high beam lamps.

How do I find the signalling cable? Here a multimeter is your best friend. Set it to measure direct voltage (V DC). With the high beam switched on, measure the pins in the connector of the high beam lamp to find the cable that gives a reading of about +12V. This is your signal cable.

Important: Be careful! If in doubt, consult a workshop manual or a knowledgeable friend.

Step 3: Choose the Right Kit for Your Lamps: Number and Power

Now that you know how to pick up the signal, it's time to choose the right cable set for your specific lights.

Number of Connections (DT connectors)

Most modern lamps use a waterproof, standardised connection called a DT connector. Our kits are clearly labelled with how many lamps they are intended for.

1 x DT: Ideal for a single LED ramp.

2 x DT: For a pair of auxiliary lights.

3 x DT: For three auxiliary lights.

4 x DT: For four extra lights, and so on.

Find our relay trays here: https://xenonkungen.com/produkt/luxtar-relakablage-2dt-12v-60a/ 

Power (Watt) - Standard or Heavy Duty (HD)?

Calculate the total power of the lighting you are going to install.

Example: 3 extra lights of 100W each is 300W in total.

Rule of thumb: For a total power up to about 300W, a standard cable set is perfectly adequate.

If you are going to power extremely powerful lamps or many lamps with a total power above 300W, you should choose a Heavy Duty (HD) cable set. These have stronger cables and a stronger relay to handle the high load safely.

Step 4: Checklist for choosing the right cabling

• Identify your car: Is it new with CANbus, or older with traditional electrical system?
• Choose the connection method: XBB Dongle for the modern car, or a traditional relay cable set for the older one.
• Count your lights: How many DT plugs do you need? (1, 2, 3 or more?)
• Add up the power: Does the total wattage exceed 300W? If so, choose an HD kit.
• By following these steps, you can be sure that you are buying a wiring harness that not only works, but makes your installation safe, durable and professional.
• See our full range of cables and relays here https://xenonkungen.com/produkt-kategori/installation/relasats-arbetsbelysning/ 
• Do you have a modern car? Read more about the XBB Dongle here https://xenonkungen.com/produkt/xbb-obd-ii-dongel-powerunit/