As featured on Motoring TV

Volume 1: Why Is There A Headlight Switch In Your Car?

Jim Kenzie has joined our team at Vicarious! Read his columns here, you don’t want to miss it!

Everybody knows the safest way to drive is with your lights on. I did that in my first car, a tiny little Fiat 600. It’s equally tiny battery – from Magneti Marelli, Italy’s answer to England’s Lord Lucas, Prince of Darkness – had a real struggle keeping up.

But safety is paramount, yes?

Canada was one of the first countries to make headlights-on mandatory, in 1990.

Good on us.

Daytime Running Lights

The preferred term was “Daytime Running Lights”, a.k.a., DRL.

There were concerns that this might burn the headlights out prematurely. Thus the approach taken by most manufacturers was to employ the less-often-used high beams at reduced intensity. The burn-out issue eventually became moot with modern long-life headlights.

Needless perhaps to say, governments got DRL wrong.

First, one eventual downside of the high-beam approach has been the near-universal adoption of taller trucks and SUVs, so following vehicles’ DRLs go right into your rear-view mirror.

Second, vehicle manufacturing standards are federal, but vehicle operating standards are provincial. There is nothing preventing you from disabling the DRL. Don’t know why you would want to, but former Car and Driver editor Csaba Csere used to advocate just that.

Third, if the DRL failed as early-production ones often did, there was no requirement for vehicle owners to fix them.

But the biggest flaw in the DRL law is that it only requires front lights, not the rears.

In fact, when DRL was proposed for the United States, some states actually had laws that if the front lights were on, the rear lights also HAD to be on.

Why? Because bootleggers would run headlights-only to make it harder for revenuers to follow them as they tried to escape at night with their illegal hooch.

Now, the original point of DRL was to make your vehicle more visible to on-coming traffic, hence reduce head-on crashes, by far the most dangerous type. This obviously is only an issue on roads with two-way traffic.

I don’t know what percentage of our traffic now runs on controlled-access freeways. Especially in urban areas, I’d bet it is really high. And if somebody is coming towards you on your side of the median barrier on these roads, DRL is the least of your worries.

Highway traffic at night

Still, front-only DRL is virtually pointless on freeways.

Why doesn’t DRL legislation require ALL lights to be on, front and rear? Like the southern US already did?

Excellent question.


In the early days of DRL, most dashboards had incandescent illumination, which only came on when you manually switched on the headlights. When it got dark, you knew to turn on your headlights because you couldn’t read the dash. My trusty 2003 VW Jetta TDI Diesel wagon is a perfect example.

But with the advent of digital dashboards, this built-in warning went away. I know you all have seen people driving along at night, blissfully unaware that they are invisible from behind. These drivers see their dash all lit up. They can see ahead of them. All’s good. Or so they think.

I wonder how many collisions have been directly caused by this “safety” device?

How can you warn such drivers that their taillights aren’t on? You can flick your own lights off and on, but the difference between your reduced-intensity high beam DRL and your regular headlights usually isn’t big enough for them to notice.

I have pulled in front of people and turned my lights off and on to warn them. They don’t get the message.

I once even had a guy think I was a cop, and he pulled off onto the shoulder. I just reached in and turned his headlights on. Probably wouldn’t dare risk that today; he might have an AK-47 under his seat.

Headlight switch

My question: why is there even a headlight switch in a vehicle? Ignition on, all lights on. Ignition off, all lights off. Dead easy.

It’s what motorcycles have done for years, and how often do we get safety ideas from motorcycles?

No more headlight switches. Problem solved.

Do you know how much a headlight switch costs?

Me neither. Depends on the vehicle I guess. For the sake of argument, let’s go in low and say $5.

With some 80 million cars built every year world-wide, I just made our roads safer, and saved the car industry $400,000,000.

You’re welcome. I think a 5% commission would be appropriate.

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