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Fitting Xtra Lights

The hows and whys of seeing where you're going at night.

by Julian Edgar

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They're distinctly out of fashion but in most cars if you want to see where you're going when driving fast at night, you'll need them. What are we talking about? - driving lights. And despite protestations to the contrary, you can almost forget upgrading the existing bulbs or fitting tiny projection-style ancillary lights if you want a lot more high beam depth and brightness. Nope, by far the best way to see further is to fit large, good quality extra lights. If the build quality is there, they don't even have to be all that high in wattage.

But like all things automotive there are a few aspects to look out for when buying, and a few tricks to the best installation. And after you've fitted them, there's one of the most critical steps of all - aiming the lights.

Lights... and Lights

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These days with the proliferation of factory foglights - most of which seem to be switched on at all the wrong times - you could be forgiven for thinking that extra lights are only for wankers. (After all, even the factory foglights don't seem to be much better in beam cut-off or penetration than using your ordinary low beam in the fog!)

In fact, some people call all extra lights 'foglights', being unaware that ancillary forward-facing lights come in three distinct types:

  • Foglights - these have a very low beam cut-off to avoid shining the light into the fog and dazzling the driver with the reflected light. Their reach is therefore limited, typically being about 150 metres. Some foglights are coloured, which further helps reduce dazzling. For driving fast at night in non-foggy conditions, foglights (whether factory or aftermarket) are useless. That makes sense - they're not designed for that purpose.
  • Driving Lights (cornering) - Cornering lamps aren't just for going around corners - the broad beam that they provide can also be useful in seeing any wildlife that is about to step (or hop) onto the road. Cornering lights have a typical range of about 250 metres.
  • Driving Lights (pencil beam) - As the name suggests, these lights have a long, narrow beam. A good pencil driving light will have a useful range of up to 2000 metres - that's 2 kilometres.... What 'useful range' means in this context is that you'll be able to pick up roadside reflectors at that sort of distance - on dead-straight roads, anyway.

A serious night driving set-up might use one cornering beam and one pencil beam. Since these variations are normally available in identical bodies, the pair of lights will look much the same, with perhaps just slightly different lens designs. (Some driving lights are available in all three configurations - fog, cornering and pencil. So you'd better be sure what you're buying!)

When comparing like with like (light with light?!), the larger the reflector, the more light that you get out of it. Sure, driving lights come with various bulb wattages, but going from a 50 to a 100 watt bulb won't make anywhere near the difference of upsizing from a tiny 50W driving light to a big 50W design. That doesn't mean that you have to be running a set of lights that look like they came off a bull-bar at an outback truckstop, but it does mean that if you reckon that you'll get the equivalent of a pencil beam reach out of a light smaller than your fist you're fooling yourself. (On any normal kind of budget, anyway.)

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There are plenty of unbranded driving lights around, often at very low prices. However, for durability and functionality, we highly recommend that you go only with a major, longstanding brand like Hella, Narva, Cibie, Bosch - or something similar. Have a look at the brands of lights used by those who really need them - long-distance trucks and buses are a good starting point.

If you buy a driving light of adequate size and from a good maker, it's unlikely that you'll need to go super high in wattage. The recommended bulb and wattage for that lamp should be sufficient. People fitting higher than standard bulb wattages are really saying that the lens and reflector aren't good enough.


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Before you venture to a retailer, work out the general type of light that you want. Driving lights are available in round and rectangular (and some oval) designs, but in addition to this they also vary in depth and mounting technique. Will the light be hung from its mount (pendant style) or will the light be standing upright? Most driving lights can be easily adapted to either configuration, but some can't - so you need to know before you go buying. Is a very thin light required or is mounting depth unlikely to be a problem? What's the maximum size that you feel comfortable with from an aesthetic point of view?

The more recent the car, the more difficult it will be to visually integrate the lights. In some cases, if you want large lights you'll need to consider adding a front nudge bar - there's simply nowhere else to place them! (Using a nudge bar mounting also reduces radiator blockage, but a couple of big Cibies on a nudge bar kinda brands you as being a resident of somewhere way out in the red dust....)

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And of course the dollars and cents come into it, too. The sky's the limit when it comes to spending money on ancillary lights, what with high-intensity gas discharge and active cornering light designs available. However, on a saner plane, you can pay from about AUD$150 to about $250 for a pair of good quality lights of the sort that we've been describing. If this is too much, look for secondhand driving lights (although remember to make sure that you're not getting foglights when you're thinking of driving lights!).

The Hella Comet 450 driving lights shown here were purchased secondhand (complete with relay and wiring) for AUD$32. They are 100W cornering light units with a beam reach of about 250 metres and with a wide secondary lighting area. As such, they are much more suitable for winding roads than for long straights.

Mounting Positions

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Because of the angle that the beam of light makes with the road, the higher the lights are mounted, the better. However, in practice, mounting the lights above or below the bumper will make very little difference to the end result. More important to the positioning are two factors - visual preference and available mounting points.

Many years ago when all cars had chrome-plated steel bumpers, it was easy - you drilled a hole in either the top or the bottom of the bumper and bolted the lights in place. Fifteen minute job. But with plastic-covered bumpers, integrated brake ducts and undertrays, finding decent mounting points can be very difficult. Invariably, a pair of custom brackets will need to be made - but hang in there, most can be formed with just hand tools and some patience.

Another major reason that very firm mountings are needed is that it's important that the driving light is as rigid as possible. A light that vibrates - or worse, moves an even greater amount under aerodynamic and vertical loads - will have a shorter bulb life, in addition to potentially flashing the beam all over the place.

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When selecting a mounting spot, keep in mind that your brackets are most likely going to need to access existing bodywork bolts that are fairly major in dimensions. If you can attach the light with a bracket that is secured in place by only a single 10-mm (socket size) bolt, it's almost a certainty that the light will vibrate badly. Either multiple 10mm bolts or a single much larger bolt will need to be used. And why existing bolts? Two reasons - (1) when you sell the car it will allow the easy removal of the lights without leaving daggy holes, and (2) an existing bolt is likely to be more rigid than one that you insert in a hole drilled through some flimsy sheet metal.

Making the Brackets

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The Comet 450 driving lights were destined for a first-series Lexus LS400. A number of mounting positions were considered; locating the lights under the bumper either side of the numberplate was aesthetically the best. But to find secure mounts at these locations would have been very involved - for a start, the bumper cover would have had to have come off. It was instead easier to mount the lights in front of the grille, which also has the side benefit of giving a higher mounting point.

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The Lexus grille lifts with the bonnet so it was decided that the flat brackets should protrude from under the grille - that is, the grille would shut down on the brackets (there's sufficient gap that the grille wouldn't hit the brackets). Behind the grille were a number of plastic screw plugs that hold the bumper cover to a metal pressing that runs across above the main structural bumper beam. The plastic screws weren't ever going to hold anything rigidly in place, but they popped out to reveal good sized holes through which new bolts could be inserted. The bracket for one light (always do one at a time!) was bent up from thick 50 x 4mm aluminium strip and held in place with a spacer and high tensile bolt. The spotlight mounting bolt needed to be shortened a little to allow clearance to the opening and closing bonnet, but other than that it was sweeeeet.

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But actually it wasn't. The bracket was strong but the sheet metal pressing that it was bolted to wasn't sufficiently rigid - the spotlight could be easily wobbled by hand. The answer was to make a stiffening piece that ran along the full length of the metal pressing. Constructed from 25 x 3mm aluminium angle, it provided extra torsional (twisting) strength, despite the fact that parts of the alloy angle needed to be cut away to give clearance for the bonnet rubbers and the bonnet release handle. Note that the aluminium angle also had to be bent to conform to a slight curve (when viewed from above).

With the strengthening piece bolted into place, the bracket for the spotlight could again be attached. This time it was remarkably secure. The process now proved, the second lamp bracket could then be made.

Note that the aluminium brackets and strengthening piece were later painted black with a spray can.

The Wiring

While if you keep a few things in mind the mechanical fitting of extra lights is straightforward enough, some people then drop the ball when they get to the wiring. However, despite the need to use a relay, if you make one vital decision it can all be pretty simple. The vital decision? That's the one where you decide that whenever the high beam is on, so are the driving lights. If you configure the system like this, all the wiring can be done under the bonnet without any need to run cables back into the cabin - in most modern cars, that makes things much easier.

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With this approach, power is picked up directly from the positive terminal of the battery and the relay is triggered straight from one of the high beam power feeds.

Note you can always have a switch under the bonnet to disable the new lights, should a situation develop where when you are running high beam you don't want the ancillary lights on. (In the real world I have come across that requirement only once - when the car had a failing alternator and the driving lights were gradually flattening the battery.)

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The first step is to wire the two earths of the driving lights to the body. Some older designs using metal bodies earth themselves through their mounting bolts, but with the plethora of plastic in cars it makes sense even in these designs to run an additional earth from the bodies to the metalwork of the car. The other wires from each of the lights (ie their power wires) run back to the relay, connecting to terminal 87. Terminal 30 (the other side of the relay 'switch') connects to the positive of the battery via an in-line fuse holder.

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There are a few things to pay attention to when doing this work. Firstly, always make sure that you use a fuse - without it, any short-circuit that might develop could lead to a car fire - and that's the case even with the car locked and you having walked away. Always place the fuse as close to the battery as practicable. (In the case of the pictured Lexus, I used a panel-mount fuse holder that I had salvaged from an old domestic hi-fi amplifier.)

Secondly, use wire of adequate gauge for the wiring discussed so far. The wire from the battery to the fuse holder and then to the relay needs to carry all the current that the two lights will draw. That could be as high as 15 amps - make sure that the wire is rated to suit.

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You'll need to make a connection to the high-beam wiring to provide the switch-on signal for the relay. Use a multimeter to probe the back of the headlight until you find a wire that has 12V on it when the high beam is on - and 0V when it is off. If the car uses a separate high beam light within the headlight assembly, finding this wire will be easier. Tap into the high beam power supply wire and then run the new wire to terminal 85 of the relay. Terminal 86 (the other side of the relay's coil) then gets connected to earth.

[In some cars, power is always fed to the high beam, with the factory switching working by earthing the light to turn it on. In cars where the wiring is like this (you'll soon know because you won't be able to find a 12V at the light that ever goes off) just wire the relay coil in parallel with the high beam. The other connections remain the same.]

The way the system works is this. When you turn on high beam, power also flows through the relay's coil, creating a magnetic field which pulls the relay contact over. This allows power to flow from the battery to the fuse to the driving lights, turning them on.

If you want to put a switch in the circuit, place it in between the headlight high beam power pick-up and the relay, ie break the wire heading to terminal 85 and put it in there. Note that unlike the power feed for the driving lights, these wires can be quite thin in gauge without any problems being caused.


These instructions refer to traditional car lighting. If your car has high intensity discharge (HID) lighting you should not probe into the wiring of the system. Dangerously high voltages are present in these systems.


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So you've bolted on the driving lights and wired them up. Think you're now finished? Wrong! Aiming of the lights is one of the most important steps in their fitment.

What you need is a dark (duh!) empty and straight road, preferable with roadside reflectors. You'll also need two people, one to adjust the lights and the other to sit in the driver's seat and call the shots.

The actual process is pretty simple. With the car idling and in a normal position on the road, adjust each light until the beam reach and illumination is best. Typically, that will mean starting with the lights too high then gradually dropping them down in aim until distant reflectors start to be highlighted - then down just a fraction more. The driver's side light should be aimed down the middle of the road while the passenger side light should be angle a little more towards the edge of the road.

Incorrect aim - especially of pencil beams - can make the difference between having fantastic additions or having lights that you may as well not bothered fitting. The difference can be that great.


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If you buy carefully and fit them correctly, driving lights can make a huge difference to night-time country road visibility. The cost doesn't have to be very high and the results are typically vastly superior to changing the bulb design and/or wattage of the original headlights.

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