Lights, wipers and demisters

By the end of this topic you can

• You can switch between sidelights, dipped headlights and main beam.
• You can decide when main beam is safe and dip it to avoid dazzling others.
• You can use front and rear fog lights only when visibility is seriously reduced.
• You can use hazard warning lights correctly.
• You can clear and demist the windscreen and rear window quickly.

What you need to know and understand

• Sidelights and rear number plate lights must be on between sunset and sunrise.
• Use headlights at night, which the Highway Code defines as from half an hour after sunset to half an hour before sunrise, except on roads with lit street lighting.
• Use dipped headlights at night in built-up areas and in dull daytime weather, so others can see you.
• You must use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres.
• You must not use front or rear fog lights unless visibility is seriously reduced, and you must switch them off when it improves.
• Hazard warning lights are for when you are stopped and temporarily obstructing traffic. On the move, only use them briefly on a motorway or unrestricted dual carriageway to warn of a hazard ahead.
• You must be able to see clearly, so all windows must be cleared of ice, snow and mist before you drive.

Which lights, and when

• Sidelights: low-power lights, mainly for being seen when parked or at dusk. They are not enough for driving at night.
• Dipped headlights: your normal lights for night driving, dull days, rain and spray.
• Main beam (full beam): for dark, unlit roads with no one ahead. Dip as soon as you see an oncoming vehicle, or when you are following another vehicle, so you do not dazzle them.
• Fog lights: only in seriously reduced visibility. Rear fog lights are very bright and can hide your brake lights, so switch them off once you can see further.
• Hazard lights: when broken down or stopped in an emergency, or briefly on a motorway or unrestricted dual carriageway to warn of a queue ahead. Never as an excuse to park illegally.

If you are dazzled

If oncoming headlights or low sun dazzle you, slow down and, if necessary, stop. Look towards the left edge of the road rather than straight into the lights. Do not flash your own lights back. At night or in poor visibility, do not wear tinted glasses or lenses that restrict your vision.

Keeping your view clear

Wipers should clear the screen in smooth sweeps. If they smear or judder, the blades may need replacing. Keep the screen wash topped up, as a dirty windscreen in low sun can be almost impossible to see through.

To demist the front screen, set the fan to the windscreen setting, turn the temperature up and switch on the air conditioning if your car has it, as it dries the air. The rear demister is a separate button, usually showing a rectangle with wavy arrows. Wait until the windows are fully clear before moving off, not just a small patch.

On your test

Show me questions can include washing and cleaning the front or rear windscreen, switching on dipped headlights, setting the rear demister or demisting the front screen while you drive. Tell me questions may ask how you would check the headlights, rear fog light or main beam warning light.

Common mistakes

• Driving at dusk on sidelights only. Use dipped headlights so you can be seen.
• Forgetting to switch off fog lights when the fog clears. They dazzle drivers behind.
• Leaving main beam on behind another car. Dip it whenever someone is ahead of you.
• Using hazard lights to park on double yellow lines. They do not make illegal parking legal.
• Setting off with a misted screen. Wait until it is fully clear.

Test yourself: Lights, wipers and demisters

Answer each question, then read the explanation. Questions come in a random order each time.

Go deeper

• When to Use Fog Lights
• Highway Code Signals