Headlights in cars might sound like a simple subject. If they’re on, they’re on, and it’s easy to tell because you can see where you’re going, and your dashboard is illuminated. Right?
Well, that isn’t always the case. Nowadays, with the rise of automatic headlights and daytime running lights, (DRLs) it isn’t always quite so easy to fathom which lights your car is showing to other drivers.
It doesn’t help that many cars nowadays have dashboard lights that come on any time the engine’s running – rather than only with the headlights, as they used to – meaning another visual cue that many drivers once used can no longer be relied upon.
So which lights should you have on, and how can you tell whether they are? And what do those headlight symbols actually mean? Here’s our guide to make sure you’re no longer in the dark.
What’s the problem? I can tell when my lights are turned on
Are you sure? Have a look at these two images.
In the top one, the headlights are turned off, meaning the car’s DRLs are active. In the lower image, the car's dipped-beam headlights are turned on.
Note that in both images, the dashboard lights are lit. Like many modern cars, this one features dashboard lights that come on when you turn on the ignition.
As a result, the dashboard lights are no longer a sure-fire way of working out out whether the headlights are turned on. In fact, the only way to tell in the above images is the slightly brighter beam from the headlights
Some cars feature a sidelight warning light, to show you when your sidelights are turned on, while others feature warning lights for both sidelights and headlights. But not all do, which means the only way to reliably tell whether your lights are turned on or not is to check the position of the switch.
Now that full-time dashboard lights are becoming commonplace, more manufacturers should be including dipped-beam telltales – but sadly, few do so, which is leaving many drivers baffled.
So, what am I looking for, then?
If you haven’t got a dipped-beam telltale – and, as we’ve just explained, you probably haven’t – then the only sure-fire way to check which headlights you have turned on is to check the switch itself.
The vast majority of headlight switches in modern cars are mounted either on the dashboard, to the right-hand side of the steering wheel, or on the end of the indicator stalk.
Every headlight switch will include positions for sidelights and headlights, and there’ll also be a button or switch to turn on your rear fog lights, which is usually located nearby.
Some headlight switches also feature an extra position, marked ‘Auto’ or featuring a headlamp symbol overlaid with the letter ‘A’. If your car is fitted with automatic headlamps, this is how to activate them – more on which later.
Some cars will also be fitted with front fog lamps which, if fitted, will usually have a switch next to or near that of the rear fog lights.
All cars will also have full-beam headlights, which must only be used if there is no other traffic on the road ahead of you, and are activated using the indicator stalk. Some cars may have an automatic full-beam function, which detects when the road is clear and turns the full beams on and off for you.
Here’s a rough guide to your headlamp switch. Not all headlamp switches will be laid out this way, but the symbols will mostly look the same.
So what different lights do I have, and when should I use them?
Part of the reason many people don’t use the correct lights is because they don’t understand the differences between the different types of lights that are fitted to their cars, or what their different uses are.
Here’s a quick guide to each of the main types of light you might find fitted to your car.
Daytime running lights (DRLs)
Fitted to all new cars released after February 2011, these illuminate whenever the ignition is on, and the headlamp switch is in the 'off' position. They take the form of either a dim headlight-like bulb in the main headlamp or front fog lamp units, a row of LEDs, or a slim, shaped light bar.
They are there to make sure your car catches people’s attention out on the road, but must not be used in lieu of normal headlights or sidelights in low visibility or at night.
This is partly because they aren’t bright enough to light the road ahead of you, but mainly because they are only fitted at the front of the car. So if you use only these at night time, your car will not be lit from the rear. What’s more, nor will your registration plate, which could land you in trouble with the police.
Sidelights (or side marker lights)
Fitted to all cars as standard, these take the form of small bulbs, often within the main headlamp bowl or sometimes in a separate section of the headlamp unit. Some newer cars use the daytime running lights as side lights, by dimming them when you turn the sidelights on.
They come on at the same time as the rear lights, so can be used in they shouldn’t be used at night because they are very dim and don’t cast a beam forward in front of the car, meaning you won’t be able to see where you’re going.
If you’re in any doubt as to whether it’s more appropriate to use sidelights or headlights, use the latter – it’s better to see and be seen than to take a chance on lights which might be too dim.
You can also use these to illuminate your car when it’s parked, if you’re afraid other drivers might not see it. Their low brightness means they won’t drain the battery as quickly as regular headlights.
Some cars have a green warning light on the dashboard to show when the sidelights are turned on. This often takes the form of the sidelight symbol, as shown in the switch diagram above.
These are what most people think of when they talk about headlights. They’re the bright lights at the front of the car that you should be using at night or in poor visibility to see where you’re going.
When you turn them on, the sidelights stay on, but they’re joined by the main headlamp units, which direct a beam out to the front and down towards the road. This means you get red lights at the rear of the car, combined with bright white lights at the front.
They must be used whenever you’re driving after sunset, but you should also use them in any conditions in which visibility is compromised – including when driving through rain, fog, smoke, or even tunnels.
Some cars – but not as many as you’d think – have a green warning light to show when the dipped-beam headlights are on. This usually takes the form of the dipped-beam headlight symbol, as shown in the switch diagram above.
These are brighter headlights which can be used when there is no other traffic around, to see further along the road than you otherwise would be able to. They’re fitted as standard to all cars.
It’s important not to use them if there is an oncoming car, or a car driving in front of you in the same direction, as they’re so bright that they can dazzle other road users.
In most modern cars, they’re turned on by pushing or pulling the indicator stalk away from or towards you until it clicks. However, some older cars might use a button on the floor that you press with your foot, while other cars might have a switch on the dashboard. They can also be flashed briefly, usually by pulling back lightly on the indicator stalk.
It’s important not to forget that they’re turned on when you meet other traffic, or you could blind other drivers. You should also avoid using them in fog, which the bright beam doesn’t penetrate; instead, it gets reflected back, meaning it’ll reduce your visibility rather than increasing it.
To that end, it’s a legal requirement that a blue warning light shows on the dashboard whenever your full-beam headlights are turned on. This usually takes the form of the full-beam headlight symbol, which can be seen in the switch diagram above.
Rear fog lights
Rear fog lights are brighter versions of your rear sidelights. They’re fitted as standard to all cars, and used to ensure your car can be seen from the rear even in low visibility.
The legal requirement is only for one rear fog light to be fitted, on the driver’s side. However, some car manufacturers fit a rear fog light on each side of the car. Often, these are part of the main rear lamp units, but some cars feature separate rear fog lights installed in or below the rear bumper.
Rear fog lights should only be turned on when visibility drops below 100m, and should be turned back off again whenever the visibility increases again. This may mean you have to keep turning them off and on through patchy fog.
This is because when they’re used in clear conditions, they can blind drivers behind you, especially when you’re in town and other cars are close behind.
All cars have an orange warning light which appears on the dashboard to show when the rear fog lights are on. It usually takes the form of the rear fog light symbol, which can be seen in the switch diagram above.
Front fog lights
Front fog lights, which are usually located in a car's front bumper, project a low, wide beam which helps you to see the edges of the road at close quarters when you’re driving slowly in fog.
They're fitted to some cars as a special equipment feature, but are not a legal requirement. Because there’s no regulation beam pattern that they must emit, which means that some are effective while others aren’t.
As a result, you may find your front fog lights to be pretty ineffective. In any case, they should only be used to complement dipped beam headlights when visibility drops below 100m, rather than to replace them.
They should also be turned off completely whenever visibility rises above 100m, as they can dazzle other road users.
But I have automatic headlights, so I don’t need to worry – right?
That isn’t entirely true. Automatic headlights detect when it’s dark, and bring on the dipped-beam headlights in order to enable you to see and be seen. But they can’t always tell when it’s foggy or raining, which means you still have to think about which lights your car is showing.
If you’re driving a car that has automatic headlights, therefore, you should always check that the lights have indeed turned on when you think they should have. The best way to do this is by checking visually, either by stopping and getting out of the car, or observing its reflection in the car in front or a shop window – when it’s safe to do so, of course.
I don’t need to use my headlights – I can see perfectly fine
Don’t forget that headlight use is not just about seeing where you’re going – it’s about being seen, too. Even if you can see clearly, it doesn’t mean other people can see you.
A good tip is to try and remember at all times not just what you can see, but also how your car looks to other road users. It’s something you should think about and question repeatedly – can other drivers see you? Can you do more to make your car stand out?
Remember, you want to do as much as you possibly can to make sure you catch the eye of someone who might not otherwise have seen you, without dazzling other road users. That is the underlying principle of safe and considerate headlight use.
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