Auto lights


Saw a mini-van the other day while driving down I-93. Every time this woman went under a bridge she put on the brakes. I finally passed her…didn’t want to be behind this type of driver. I’m a few car lengths in front of her and we pass under another bridge and saw her head-lights come on, then off as we clear the bridge. That’s when I realized what was happening. Each time she drove under a bridge the sensor would think it was night time and turn on the lights (front and rear). The way this vehicle implemented this feature is real dangerous. My wifes Lexus and my highlander have this feature, but when I put it in auto light mode the rear lights are always on…only the front lights turn on and off. This vehicle it looked like she was braking when in fact it was the auto lights turning on the lights thinking it was dark. I wasn’t paying attention to what car it was…some 15+ yo mini van. Hope the newer versions of that vehicle don’t work that way.


Really? I have never seen that. What type of car?

I’ve seen DRL’s glowing at night with NO rear lights on but not the other way 'round. Or not so I’ve noticed. Automakers started including auto-lights, I think, because SO many people were wandering around in the dark with NO tail lights on.


That’s a good argument towards turning your lights on when you turn your car on and just leaving them on…Would help the morons who use only DRLs and forget to switch their head lights on (and the tail lights…) when it gets dark/the vehicle doesn’t have a light sensor


I have auto lights on both vehicles. The Volvo has DRL’s and the rear tail lights are not on until the headlights come at dark. The other one does not have DRL’s so the tail lights are not on until the headlights come on.


With my current and previous cars, there was a short delay before the lights came on, which was enough to prevent this situation.


I just leave my lights on all the time.


Although most will not understand I am an old school dinosaur adverse to auto everything concerning operating my motor vehicles. My theory is the more I am involved in the operation the more I stay focused. So far it is working. I hope when I am reaching incompetence I have the sense to surrender my license. Most likely because I am a school trained military aviation/OSHA certified, and experienced safety specialist. I’m not a “Luddite”. I do love having Thousands of songs available on my vehicle’s stereo stored in an inexpensive USB drive. Unfortunately I would have to scroll through them on the stereo visual display to locate a certain one. and need to safely park to accomplish that. Following the advice of the late, great Jim Morrison (“The Doors”) “Keep your eyes on the road and your hands upon the wheel”. I have started using “random” which is like a radio station that only plays songs that you like with no commercials. If it selects a song I don’t want to listen to at that time I can advance to the next one with a switch located on the steering wheel.


I see this all the time in the tunnels here in Duluth and nearby, but not with overpasses. I agree there should be some more delay built into systems that turn on the headlights so quickly.

So here’s a new game: wager on whether a specific car will do this. And, over time, build up a data base of those more and less quick to turn on the lights.


Headlights turning on is NOT the problem. It’s behind someone when the tail lights keep going on and off. It looks like they’re braking.


I’d have to go look in the manuals again but I’m quite sure there is a sensitivity setting that can be programmed in. My Pontiac is much more sensitive to twilight than my Acura but they usually have a delay to avoid the lights going on and off. My lights do go on though when I drive in the garage so it really isn’t much of a delay. I actually carry a small piece of headliner material that I put over the dash sensor in low light conditions to turn the tails on and also so I don’t have to remember to shut the lights off when I park.


Good, informative post OP. I’ve never considered that as a reason why sometimes the car ahead of me brake light’s are turning on, apparently randomly. Next time it happens I’ll watch carefully too see if ambient lighting’s effect on the automatic lighting system is the actual reason.


Pay close attention and see if you can recognize the difference between brake lights and tail lights, that might alleviate a panic while driving though shaded areas or under a bridge.


The difference is the third brake light, so that’s not too hard to do.


First of all, since 1986 US cars have had to have a third brake light in the center either on the trunk or in the rear window (and sometimes mounted up high). If the third brake light isn’t going on then it is not a braking issue (except in the rare case of all the lightbulbs being burnt out in the third brake light).

Second of all, most auto headlight functions have a sensitivity setting that can be adjusted so that headlights go on and off automatically at a threshold that the driver selects. Mine are set to be slightly more sensitive than the factory settings since I found that the headlights took too long to come on at dusk.


And many times the Cyclops light isn’t working.


Not to take a diversion but there was a time when there were no brake lights. Seems to me the neighbor had a 49 or something Plymouth or Desoto that had a brake light in the center of the trunk that was sold as a new safety feature.


And in 49 there were less then 5% of the cars on the road today.


@Bing. I know the Chrysler products had a center brake light and this started with the 1942 models and continued through the 1949 models. The 1950 and later Chrysler models had the tail lights and brake lights on either side under one lens with dual filament bulbs just like other makes. I don’t know when cars first had brake lights. My Dad’s 1939 Chevrolet had brake lights and I think the Model A Fords had a brake light combined with a single tail light.


My 2017 4Runner works the same as the minivan - the tail lights don’t come on until the headlights turn on in “auto” mode. Not sure why this is dangerous as tail lights are not nearly as bright as brake lights and the 3rd brake light desn’t come on. In a tunnel or under a bridge the tail lights may seem brighter but still, If this were dangerous, wouldn’t we all be braking when people turn their lights on manually?


You will have to excuse my apparent ignorance, but I can’t figure out what that accomplishes.