Rain sensors don’t actually collect moisture.
Well, at least not the ones on cars that help run your rain-sensing wipers.
So how do they actually work?
It’s all about light and reflected light.
The rain sensors are actually a component that reflects LED lights onto your windscreen.
The same component then measures how much light is being reflected back into it.
However, if there are raindrops on the windscreen, not all the light being beamed gets reflected back.
The rain sensors detect this, and are programmed to activate your wipers.
The wetter the windscreen, the less light is reflected back.
This then tells the rain sensors to increase your wipers’ speed.
Auto headlights use a similar system, too.
Automatic headlights help drivers by ensuring the headlights are switched on when conditions get dark.
Most cars have them.
Ironically though, the number of drivers driving around without headlights in Singapore seems to be increasing.
But we digress.
Auto headlights operate off a light sensor mounted behind your front windscreen.
Like rain sensors, a light sensor sits in front of your rear view mirror.
Light sensors don’t beam light onto the windscreen, though.
Instead, they have photocells that collect light.
When the light collected by the photocells falls below a particular level set by the carmaker, the headlights are switched on.
Both systems can be switched off if the driver wishes it.
Having your rain-sensing wipers on isn’t always useful.
For instance, if you’re driving through a car wash, you probably want to switch them off.
After all, you want the cleaning crew to do their job of cleaning your windscreen and wipers.
But in the case of automatic headlights, we recommend you leave them on.
You can see an “Auto” setting on your indicator stalk or control dial.
Leave it there.
Automatic headlights switch themselves off when you switch off your engine.
And just because your instrument panel is lit, doesn’t mean your headlights are already on!
