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Mechanically Speaking: Fog lights can help you see and be seen

"Recent trips up and down the local roads have been a challenge. Thick fog prevails, and poses a real driving challenge."

When you don’t see the sun for a week or so winter can get depressing. Even worse is a week of fog, especially when you have to drive in it.

Recent trips up and down the local roads have been a challenge. Thick fog prevails, and poses a real driving challenge.

Many vehicles are equipped with fog lights. If you have driven with fog lights you know they help in certain fog conditions but they are not a revelation. A fog light is mounted down very low on the front of the vehicle and it puts out a very broad beam of light. The light is sharply cut off horizontally to prevent any upwards glare.

To understand glare just turn your high beams on in the fog. The light reflects off everything in front of your eyes making driving a nightmare of sorts especially in a foggy snow storm.

The fog light’s broad beam puts some extra light to the sides of the road and helps to better define your path. They are especially helpful when the shoulder of the road is defined by lines or barriers of contrasting colour. When the shoulder of the road is a snowbank and the road is covered in snow the fog light’s effectiveness wanes.

The ineffectiveness of many fog lights is a result of the plain and simple fact that they are just not working. Their location below the bumper puts them in a war zone of sorts. In many cases their lenses have been destroyed by rocks and after a lense is broken and moisture gets in the bulb is not long for this world. Most fog lights are also lower than curb height. This means a few parking curb collisions have likely unfavorably adjusted their positions if not totally broken their mounting system.

The fog lights relative usefulness in most customers’ minds has become clear to me by the simple fact that many people choose not to pay to fix these lights.

Daylight fog presents a challenge that no fog light can provide any help other than the obvious. It will give oncoming traffic a much better chance of seeing you. A customer of mine recently pointed out that we have grown complacent when it comes to driving in the fog during daylight hours.

Fortunately all vehicles 1990 model year or newer have had to have daytime running lights in Canada. The indisputable fact that vehicles with their lights on are much more visible in all driving conditions resulted in this legislation.

So by default when we get in our vehicles and drive away our lights are on. In most vehicles the high beam lights are turned on at a reduced power level. Typically a daytime running light module (DRL) is in charge of this operation.

Unfortunately these modules do fail and on some vehicles there is no indication of their failure. Some vehicles do indicate when this system is inoperative but many drivers may not recognize the indicator or choose not to fix the problem.

Many of us have probably grown complacent about using our headlights when driving in daylight fog assuming our daytime running lights will take care of our visibility but there is a very real problem with this assumption. Daytime running light modules in most cases do not turn on the tail lights. Your vehicles visibility from the rear is compromised.

To be seen in the fog turn on your lights.

Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: nutechauto@telus.net