Car headlights (and brake lights) questions

In days of old, car headlights and taillights came on and went off according to the headlight switch only. Nowadays it seems that many cars require the ignition to be on. What’s the rationale for the switch? Is it just to possibly running down the battery?

On my previous car, the brake lights also required the ignition to be on in order to function. Why would that be

Wrong question, IMHO. The question is, why the hell did anyone want their headlights OR their brake lights on when the car’s off? Flashers, sure, but headlights?

Short answer is yes it prevents the battery from being drained by from the headlights being left on.
I have never seen a car that required ign on for the brake lights to work.

Many a time in younger days headlights were used to illuminate a “situation.” So, we found 'em useful for that as well as driving.

The car that required ignition for brake lights was a BMW 735i.

Leave the car off, turn the lights on, light up the campsite, football field, parking lot, …

As aktep describes.

As one who often drove to my first college class before 7:00, I know the pain of forgetting to turn off my headlights once I parked. I’d spend the whole day on campus, then go to my car at 4:00 pm with a dead battery.

Nowadays, I drive with my headlights on all the time, even bright daylight. To go with that, I also developed the habit of turning off my lights no matter what.

But just in case, I do have a set of jumper cables in my trunk. :D:D

In an emergency, such as having Old Rolf cough to a stop on a 2-lane county road and seeing the approach of headlights in the other direction, one would pray for the ability to flash the headlights. Having no lights at all when the driver has walked away with the keys is unthinkable, in my opinion.

My '93 Jeep Cherokee is set up so that the headlight switch only works to turn the lights on or off when the key is turned on. So far, so good, you can’t turn the lights on when the car is off. But you can’t turn the lights OFF when the car is stopped, either. If I get out and notice I’ve forgotten to switch off my headlights, I have to get back in the car, reinsert the ignition key, turn the car back on and turn the lights off. I think that’s stupid.

Day Time Running Lights are for safety, vehicle is more visible.

Wow, racinchikki, that setup is kind of anti-prevent running the battery down.

Are Day Time Running Lights the normal headlights?

here’s a tip from my gamma: If you need to switch your headlights on during the day, lock the door beside you - when you go to get out of the car, the door is locked (ou will have forgotton), you go to unlock the door, and remember at the same time, to switch your headlamps off.

Works fine in older cars. In newer cars I have driven, lights go off when the ignition goes off, so there’s no chance of the battery going dead. Some people might have a problem with not being able to light up, er, “situations”, tho I never have.


I don’t know about all cars, but my 2000 Pontiac Bonneville uses the brights, however, they run considerably less bright during the day. The headlights (next to brights) come on automatically if it’s dark enough outside, in which case i can turn brights on full power with the turn light thingy.

In my experience (European cars), newer cars switch the headlights off with the ignition, but leave the sidelights on, presumably to conserve the battery.

Also, I think there is usually a way of overriding this if you really do want to have the headlights on with the ignition off, but it’s something you have to make a conscious effort to do.

e.g. Fiat cars have a small button next to the ignition switch that you have to push in and hold while you are turning the ignition off.

I suppose you might want to use this if for whatever reason you want to leave the headlights on but don’t want to leave the keys in the car.

BTW, German cars have an extremely irritating type of parking light which comes on if the indicator is left on with the ignition off. In this case only the sidelight on the side of the car that the indicator is set to remains on. (Does that make sense?) I have run down many an aging battery by forgetting to cancel the indicator after switching off the engine…

I’ve not had a car yet where the brake lights don’t work with the ignition off. This seems like it could be dangerous. Say you’re stalled at night and your headlight switch popped off in your hand – it’d kind of be nice to have brake lights so no one rearends you.

My current, newer, modern car (Continental) doesn’t have daytime running lights (DRL) at all. My previous car (same as SlickRoenick’s) had DRL, and I’m pretty sure it’s common across the entire GM line (my current car is a product of Ford, and should be a “step up” from a Bonneville [but that’s another story]). But in both cases, the headlights come on automatically when the car thinks it’s dark enough. Works for me and I never have to screw with turning lights on or off. The Bonny’s owner’s manual explained that DRL’ were the high beams operated at a lower voltage. Since the key is visibility, I think this is probably common in most DRL systems.

In in the case of both cars, the automatic headlights off time is programmable via the computer (actually, on the Bonny I think it’s a knob).

Hint: if you have your lights on automatically and need to turn them off, flip on the parking lights manually. It worked on my Bonny and my Continental.

Yeap. They’re fog lights. Like, when you’re parked somewhere and it’s a foggy night, the light that’s on the outside (road side) of the car is left on, so as to warn other cars that there’s an obstacle (parked car) ahead.

Adding to that explanation, it’s not just a fancy feature of German (and most European) cars that lights can be turned on when the engine is off, even when the keys are removed. Cars are required to be built that way by law (in many European states). When you are parking on a road with no street lamps at night, you are required to light your car that way. All motor vehicles except very light motor bikes are therefor required to provide the ability to run a light like this solely on battery power.
The feature of having only the lights of one side on actually saves energy, compared to leaving all the lights on.

I don’t think they’re exclusively for use in fog, although obviously they’d be extra useful then. I’ve usually seen them referred to as parking lights. I’ve certainly never used them intentionally, despite having them for about three years on a car I owned. If I’m stopped in a dangerous place for whatever reason I always use the hazard warners, which are brighter and more conspicuous anyway.

I usually lag behind current car technology by a decade or so (my current car is 15 years old), is it true that cars now switch your lights on for you when it gets dark?

Wow. When I think of all the times I’ve driven for miles in the pitch black wondering why I couldn’t see anything, then realising that I forgot to turn on the headlights…

What a life-saver!:smiley:

In the US, cars used to have “parking lights”, which were tiny red bulbs mounted on the rear fender. I was too young to know how they were turned on, presumably a dashboard switch. This was ended during WW II as part of general blackout regulations in anticipation of enemy bombing. Little did we know that the only part of continental US that would ever be bombed were some Oregon forests. But I distinctly recall these light on every fender, for years after the war, although they were not lit.

I have seen some people walk away from their cars with headlights on & then a couple minutes later they are off. In that case not even the key is in the car at the time.