4WD Action - Five Minute Instant Expert - Lights

Posted under: Whats New ! Posted on: Jan 13, 2016

Five Minute Instant Expert

Brought to you by Drivetech 4x4, this article was published by Australian 4WD Action Magazine (Issue 240 - 2015). Words by Allen Hodges, photography by Wes Whitworth. To download the full article, CLICK HERE.


Become a light bar expert in six easy steps.

Who doesn’t want that extra flood of light when you go on those last minute night runs? A good option for improving visibility off-road is to fit a light bar to your 4WD as it will give you a crisper whiter light.

In this issue we are going to go through the six steps you need to fit and wire up a light bar using one of Drivetech 4x4’s new 20inch LEDs. A universal harness that has all your relays and switches is also available, so all you have to do is plug it in and connect some wiring.

Step One

Pick a light bar that’s right for you and your truck. We measured the space we had and found a 20inch light bar would fit perfectly on the centre of the bull bar. We went with the Drivetech 4x4 unit as it represents great value for money and is very easy to install.

Step Two


With full installation kits available, fitting your light bar is fairly straight forward. Position it on your bullbar and secure it into position. Different manufacturers have varied ways of mounting their light bars; some use “L” brackets on the ends and others use a moveable mount at the bottom of the bar. 

The Drivetech 4x4 unit can be fitted both ways as it has side mounted “L” brackets and moveable bottom mounting bolts. Don’t forget to check with your local roads and traffic authority when choosing the best mounting position for your 4WD.

Step Three

 150519 DIY Light install_017.jpg

If your light bar doesn’t have a pre-made harness available like this Drivetech 4x4 unit, you can wire it in with two core wire and make your own harness. First, disconnect the negative terminals of both the main and auxiliary battery. Next, run power from your main battery positive terminal through a suitable fuse to terminal 30 on your relay, and then another wire from terminal 87 up to the light bar. To turn it on and off, run a wire from terminal 86 on the relay to one of the headlights and splice into the high beam wire, then from terminal 85 to the on/off switch on your dash. This configuration means your light bar will only work when the high beams are on. 

NOTE - When choosing the wiring and fuse for your light bar, it’s best practise to use gear that’s rated to 2-3 times the maximum current draw of the light. For example, if your light bar draws 15amps, use a 30amp fuse and wiring.

Step Four 

Run the power wires from the output terminal on the relay to the power supply on the light bar and solder the connection. Run the earth wire from the battery to the negative wire on the light bar and solder the connection. Ensure all your connections are soldered securely and any terminals are crimped correctly, then insulate and secure your wiring using conduit and cable ties.

Step Five


Test the operation of your light bar to ensure it turns on and off by the switch once the high beams have been switched on. Park your 4WD forward facing about one and a half meters off a wall and adjust the aim of your light bar so it’s roughly in line with your headlights, then tighten up all mounting bolts.
NOTE - Loosening the mount bolts will allow you to adjust the direction of the light’s beam.

Step Six

Once you have it all connected and aligned, go for a run with your mates and show off your handy work. At this stage, check the alignment once again and readjust if required.


Positive Vs Negative Switching

There are two ways for a relay to switch on and off. Positive switching is when the relay uses the positive wire as a signal wire to turn your lights, or whatever is in the circuit, on. Negative switching is when you use a negative as the signal wire to actuate the relay.

What we used...