Auxiliary light wiring: guide to the right choice

What does a relay wiring kit do for auxiliary lights?

A relay wiring kit collects the cables, relay, fuse and connections needed to power the auxiliary lights separately from the car's regular lighting. In a standard relay connection, the high beam signal turns the relay on and off, while the current to the lights goes through the separate supply.

So there are two things that need to work: the power supply to the lights and the signal that controls them. A set of the correct lamp connectors may still need to be supplemented to work with the car's high beam control.

Choose the right connector and number of lamp connections

First check which connector the lamp has and how many pins it uses. DT connectors come in several designs, and DT and DTP are different connector series. Choose according to the lamp specification and wiring diagram, even if the connectors look similar.

On Luxtar cable kits it is important to distinguish the connector designation from the number of connections. In DT-3 X2, DT-3 means three pins in each connector and X2 two lamp connections. This does not mean that the kit is for three extra lights.

We recommend that you start with Luxtar's relay cable kits and choose the design according to the lamps. Here are three examples for 12 V:

Also check what the extra pins are used for, for example position lights, and that the functions match the lamp's wiring diagram. The same number of pins is not enough as a check. Also measure the cable route so that the connections reach without the wiring having to be stretched.

How much can the cabling handle and what cable area is needed?

Based on the actual power consumption of the lamps in the power mode to be used. The wattage of the model name does not necessarily correspond to the consumption, and several lamps load both the common supply and their own connections.

Therefore, check the cable set's stated load limit together with the cable area, cable length, fuse and contacts. A relay marked 80 A does not mean that each contact, or the entire complete set, can be loaded with 80 A. There is no general limit where all standard cables can handle up to 300 W and anything above that requires HD.

The cable area is usually specified in mm² and needs to be selected according to the current and the length of the cable run. A longer cable gives a greater voltage drop for the same current and cable area. Follow the instructions of the relevant kit and lamp, especially if the wiring is to be extended. If the permissible load per connection is unclear, let us check the combination before you order.

Does the car need XBB or other high beam control?

It depends on how the high beam is controlled in your particular car. The year of model or whether the car has LED, xenon or CANbus is not enough to choose the connection. Check which control signal the cable set needs and which solution is supported for the car model and its equipment.

XBB Dongle with PowerUnit is an alternative when there is a working recipe for the car. The dongle is plugged into the diagnostic socket, OBD2, and communicates wirelessly with the PowerUnit. The lights still need cables for the power supply. Start with the compatibility check in XBB installation manual before choosing the solution.

The PowerUnit has its own load limits. For the standard XBB PowerUnit, the manufacturer states that lighting that draws more than 15 A needs a separate power relay controlled by the unit. Select the wiring for that connection and check the relay socket connections. It is not enough to replace the relay in any ready-made wiring kit.

The actual connection and control signal checking is described in our guide to installing additional lights. For placement, mounting and wiring, see our guide to install led ramp on car.

Checklist before ordering cabling

Have the details about the car and the lights in front of you when comparing relay cable sets:

• Correct system voltage for car, lights and wiring harness.
• Correct connector series, number of pins and connection of the functions.
• Enough lamp connections.
• Permissible load for both the entire kit and each connection.
• Cable length that is sufficient for the intended routing.
• A solution for high beam control that works with the car.

If something is unclear, we will help you choose. Send us the car model, year, information about the original headlights and links to the lamps, so we have a better basis for checking the wiring and any control module together.