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My previous article dealt with fog lights. This article will discuss driving lights. There will be some unavoidable repetition, but I’ll to try to keep it to a minimum.As the name implies, driving lights are designed specifically to assist a driver in seeing the road when driving after dark in clear conditions. They augment your high beams. If it’s foggy or snowing heavily, driving lights are NOT what you want to use. Under absolutely no circumstances should your driving lights work when your high beams are not in use because they put out as much or more glare than your high beam lights. Think of them as super high beams, and practice common courtesy if you have driving lights. You wouldn’t want to be trying to see on a dark night if somebody coming the other way didn’t turn off his driving lights, would you?

Driving light beam patterns and penetration

There used to be a French company (Marchal) that made driving lights with a variety of beam patterns, but they appear to be out of business (any stories that a company in Japan is now making them may or may not contain much truth). I used some Marchal bowtie-pattern driving lights for about a year once, but did not like the beam pattern so changed to some Carellos (an Italian company that also appears to be out of business) with an oval beam pattern and was much happier. Today, about all you can find (unless you’re extremely lucky on e-bay) will be driving lights with an oval or a pencil beam pattern. For use on roads in the Midwest, only the oval beam pattern makes any real sense because you will be more interested in seeing well out to a distance of a couple of hundred yards rather than the half mile or more a good pencil beam will penetrate.

An oval beam pattern has an oval hot spot with a flare of lesser-intensity light surrounding it. The hot spot is wider than it is high. For instance, the legendary Cibié Super Oscar driving light had an oval beam pattern with 10 degrees of vertical spread and 34 degrees of horizontal spread, and had a reflective range of 5,000 feet. When projected down the road, an oval beam spreads out to cover two or more lanes of traffic and, given the right design, can significantly increase the distance you can see from behind the wheel, though the degree by which this will happen depends on the type of high beam headlights you have.

A pencil (or spot) beam is just what the name implies. The hot spot appears to be almost perfectly circular when projected on a wall, and is designed for maximum distance with minimum spread. The Super Oscar pencil beam, for example, had both vertical and horizontal spreads of 13 degrees, and a reflective range of 9,500 feet (about 1.8 miles). Marchal’s 700-series lights were similar in size and output to the Cibiés.

When I lived in the Arizona desert, oncoming traffic was rare to non-existent, and wild burros are far worse than deer because they think they own the road, won’t move except to get in your way, their natural color blends perfectly with the background day or night, and their eyes are not reflective. I used one driving and one spot beam to get additional spread and distance over my Cibié QI headlights, and the reflective distances Cibié claimed are conservative – on one dark night (no moon, no ambient light, and no oncoming traffic) on a level stretch of road, the added lights would illuminate a reflective road sign that was more than 3 miles away. I saw burros on the road after dark on several occasions, and with those lights I could see them far enough in advance that no panic maneuvers were ever necessary.

Iowa is a different story, and a pencil driving beam here is probably of much less value than a shorter-range oval beam. However, not all oval driving beams are created equal. Manufacturers rarely provide photographs of what each of their lights’ beam patterns looks like when projected on a wall, so about the best way to choose is to depend on the manufacturer’s reputation. KC HiLites have been popular with off-road drivers (I’ve seen them mounted on a roof-top bar on Jeeps and other off-road-type vehicles) though I have no personal experience with them. Hella has been a trusted name for decades (though I don’t like their QI headlights, I do like their 500-series driving lights), PIAA is a major supplier of good after-market lights, and Cibié is still making very good lights. There may be others as well.

Here are six illustrations of driving light beams:
(Click any image for a larger view)

Illustration #1

This shows two driving light beams projected onto a garage door. The beams are basically circular but have an oval hot spot in the middle. Note the amount of fairly bright flare around the hot spots, which is important in helping drivers see things like overhead signs.

Illustration #2

This is from PIAA and shows how they design their driving light beam pattern. Note that instead of the 90 to 100-degree spread of their fog lights, their driving beams have a spread of from 10 to 25 degrees. They use a beam pattern that’s similar to their fog beam, and I’m not sure I’d find it as useful as one that is more oval to round in shape. On the other hand, perhaps this emits less glare for oncoming traffic while still providing good distance illumination. I have no personal experience with PIAA driving or fog lights. Click here to view the PIAA Lamp Technology Guide.

Illustration #3

This is from KC HiLites, and is the same illustration from them that I used in the article on fog lights.

Illustration #4

This shows my MINI’s HID low beams. Compare this with the next two photos, all three of which were taken in the same location with the same camera lens and exposure settings. None have been “Photo-shopped”. As noted in the fog light article, the two dark stains on the pavement are about 25 feet in front of the car.

Illustration #5

This shows my MINI high beams. Because I have a 2004 car with HID low beams, the low beams stay illuminated when I select high beams. All that changes is that two QI high-beam units are added to the output. You can see the slightly yellowish appearance of the QI high-beam area at the far edge of forward illumination, and you can now see the taillight reflectors of a car that is parked at the side of the road ahead of me.

Illustration #6

As many of you know, I’ve got four auxiliary driving lights mounted on the front of my MINI. This shows what I see when I’ve got them on in addition to my high beam lights. There is not much difference between illustrations #4 and #5, but there is a vast difference between illustrations #5 and #6, which is why I added the four driving lights. If you look closely, you will see the four individual driving beam patterns as they cover the road starting just past the oil stains. There is also a substantial increase in foreground light, but that does not constitute a serious problem because there is a commensurate increase in the amount of light projected onto the road surface much further down the road.

Location and Aiming

Well-designed driving lights should be mounted at least as far above the ground as your high beam headlights, and a bit higher is even better. Mounting them below the bumper, where your fog lights should be mounted, is an exercise in futility because you may be putting out a lot of lumens in a good beam pattern, but it will either put the light too close to the car to be useful or it will be so close to parallel to the road that it won’t be useful. You want the beam pattern to play out onto the road surface, and having the light mounted at an appropriate height makes that possible. The Tire Rack suggests a height of between 14 and 30 inches above the road surface, with higher being better. The Society of Automotive Engineers (SAE) guideline for aiming driving lights (J581) says proper aiming technique is as follows:

1. Park your MINI on the level so the front of the car is 25 feet from a light-colored wall.
2. Measure the vertical distance between the center of the driving light and the ground.
3. Place a horizontal mark on the wall at that height (I use blue painter’s masking tape).
4. Aim the lights visually so that when the light is facing straight forward, the center of the driving light beam’s high-intensity portion is 1½ inches below the mark on the wall.

Daniel Stern Lighting has much more extensive directions, including information on how to settle the suspension, how to determine the axis of each light, and the load simulation you should have in the car when you aim the lights. His recommendation of having the high intensity portion of the beam strike your aiming mark dead center conflicts with that of the SAE. I’ve found the SAE guidelines provide me with better illumination of the road ahead.

Proper aiming will ensure that your lights provide the best possible illumination for you. Keep in mind that driving lights are not designed to help you see when you’re in fog or heavy snow – they’re designed to help you see in clear conditions when there’s no oncoming traffic.

Using driving lights

The first, and perhaps single most important, rule about the use of driving lights is simple. Never use them when there’s any oncoming traffic. They should be used only away from any on-coming traffic, even when that traffic is separated by a large median such as that on the Interstates or other freeways. If you can see the headlights of oncoming traffic, be courteous and just use your low beams.

As mentioned above, I have four driving lights on the front of my MINI. Two of them are aimed dead straight ahead, and two of them are aimed in a slightly “wall-eyed” fashion – the right one toward the right ditch and the left one toward the left ditch. They are all aimed so that at a distance of approximately 50 yards the hot spots begin to merge, providing me with a wide spread of light that not only gives good distance penetration but also gives me a fighting chance of seeing the raccoon, opossum, or deer that’s about to climb out of the ditch and into my path.

In terms of the beam pattern, I got very lucky. I bought my lights as a kit in order to get the bar, which accepts four lights and mounts to the front sub-frame of my car (rather than to the grill). I was fully prepared to spring for four Hella 500s if the beam pattern of what came in the kit was not what I wanted. Eventually, I’ll need to replace the original lights with Hella 500s because at least one of the reflectors is beginning to degrade after exposure to nearly a decade’s worth of Iowa winter weather, but until then I’m happy with the lights that came with the bar.

Those of you who have bi-Xenon HID headlights (with both low and high beams from the HID capsule) may not benefit from the addition of QI driving lights simply because the HID high beam is probably going to provide more light in a very good pattern than will a QI driving light (see my article on headlights for lumens per watt and degrees Kelvin of each type of light). When I bought my MINI in 2004, however, the car’s HID headlights utilized a QI H-7 bulb for high beam and the high beam could not be aimed independently of the low beam. I was dissatisfied with the minimal additional useful light from the MINI high beams (see illustrations #4 and #5 above), so I got the driving lights to remedy the situation. I have no personal experience with MINI’s bi-Xenon HID headlights.

My driving lights are wired per the directions I provided for fog lights (except the relay trigger comes from a high-beam wire) because there’s a section of Iowa Code (321.403) that limits the number of auxiliary lights on the front of a vehicle to three (I have four) and another section of Iowa Code (321.420) limiting the total number of headlights and auxiliary lights that can be lit at any one time to no more than four. I’ve never been questioned about it, but I included a switch in my wiring so I’ve got a quick and easy way to turn off the driving lights in the event that becomes necessary to satisfy the law.

Be courteous and stay safe – use driving lights for the purpose for which they are designed and don’t expect them to do double-duty as fog lights.

Mounting and wiring driving lights

If you decide to install and use driving lights, you’ll need to wire them yourself unless you purchase the optional MINI driving lights and have the dealer wire them. If you’ve done that, everything should work correctly, though you should probably check their aiming just to be sure they put the light where you want it.

There are basically two options in terms of mounting location and technique. The MINI driving lights mount to the grill of the bonnet and go up and down when you raise and lower the bonnet. Specifically because I did not want that arrangement, I searched for nearly a year before I was able to find the bar I’ve got, which attaches to the front sub-frame of my Gen-1 car and stays in place when the bonnet is raised. If you are OK with having your driving lights mounted to the grill of your car, I think all such mounts are generally similar in design and perhaps even completely interchangeable. If, like me, you want to mount them solidly to something that doesn’t move, there is at least one such bar available for the Gen-2 cars.

Wiring your driving lights is similar to wiring fog lights as I described in that article. You’ll need a wiring diagram for the car, common wiring tools, zip-ties, 14-gauge wire, a switch, an assortment of connectors (or a soldering gun and resin-core solder), perhaps some shrink wrap, two 10-amp in-line fuses, and a 20-amp fused relay. Your lights may come with a wiring harness, and may contain a switch and a relay, which will save you some time and money. As I said about fog lights, NEVER wire auxiliary lights without a relay! Once everything’s ready, proceed as follows:

1. Disconnect the battery of your car.
2. Find a wire that feeds power to your high beam lights. You will tap into this wire.
3. Find a location for the relay. Don’t hide it, because if the fuse blows you’ll want easy access.
4. If you want the ability to turn the lights off when you have your high beams on, find a location for the switch you’re going to use. This is how I can turn off my four (illegal number) driving lights should the need arise while retaining the ability to use high beams.
5. Run a wire from your tap into the high-beam power source found in #2 above to your switch. If you’re not using a switch, run the wire to terminal #85 on the relay.
6. If you are wiring a switch into the circuit, run a wire from the other side of your switch to terminal #85 on the relay. If you are not using a switch, skip this step. Caveat: Check the wiring diagram that comes with or is molded into the body of your relay. I’ve used the terminal numbers from the relay on my car, but I can’t guarantee the numbering scheme is consistent across all makes of relays.
7. Run a wire from terminal 86 of the relay to a good, solid ground.
8. Run a wire from a good power source (the hot side of a fuse block or other good power source) to terminal 30 on the relay.
9. Run a wire from terminal 87 on the relay to each of the driving lights, placing one of the 10-amp in-line fuses into each wire before it reaches the driving light. Some relays come with two output terminals and you may be able to wire one driving light to each output terminal. Check the wiring diagram for your relay.
10. If your lights came with separate power-in and grounding wires, connect the grounding wires to a good, solid ground. You may need to add a length of wire to reach a solid ground. Some lights ground themselves on the mounting bracket, assuming that bracket makes good contact with the car’s chassis. I’ve never put much faith in that, so I’ve always run a separate grounding wire, which is what I recommend.
11. Double check all your connections. If you put shrink wrap over each connector as you went, heat it carefully until it shrinks tightly around the connector.
12. Reconnect the battery, start the car, turn on high beams, and turn on the driving lights (if you’ve used a separate switch). Then, flip to low beam to see if the driving lights go off as they should. Once you’ve made sure the driving lights work correctly, you can aim them. You’ll probably need to re-program your windows and re-set your car’s clock, but then you’re done.