The Headlight Flash. What Does It Really Mean

August 19, 2010 by Lug_Nut · 37 Comments  
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IMG_1313The flashing of one’s headlights is something we have seen for years throughout Europe.  It was, and is, used to generally signal the intention to overtake another vehicle.  Kind of a heads-up and to ensure the vehicle being passed was aware of this action.  For this use, nearly all the vehicles sold in Europe for the last forty plus years were equipped with a momentary headlight switch built into the directional signal.

This quick flash feature started to show up on North American vehicles in the late 80’s, early 90’s.  Since then we have all witnessed vehicles on the highway, on city streets and in mall parking lots using this visual communication.  The problem being, the headlamp flash is conveying a specific message.  But who is the message intended for and how is it translated?  Let’s look at some of the things this light flash may be saying.

  • Police speed trap ahead
  • I think I know you.  Hi!
  • Your lights or high beams are on and shouldn’t be
  • Your lights are off and should be on
  • I guess that isn’t the wipers
  • Go ahead and pull out
  • Don’t pull out, I’m going through
  • Get out of my way I’m in a hurry
  • Go ahead and cross the road, I see you
  • Don’t cross the road, I’m here and coming by.
  • And many more……….

Well, first of all, warning of a police speed trap in that manner is illegal in most, if not all, places.  But, with a motor home or tow vehicle combination, it is highly unlikely we will have to be concerned about speeding anyway.

From the list of some of these meanings it is easy to understand the dilemma of the intended recipient.  This has many times lead to accidents involving serious injury or death, not to mention thousands of property damage events.  Many of these visual signals are not legal, are not supported by the highway traffic act and are not deemed a safe method of communicating a message.

So, is there a good use for this signal? Well, of course the I.C.C. application of flashing a passing vehicle when it is clear to pull in is certainly a valid use.  Additionally, though not necessarily recognized as a legal signal, a highway flash indicating of a hazard ahead seems both practical and may help to increase safety.  The hazards would be things like a vehicle accident ahead, deer, or the like, on or near the roadway ahead, or any obstruction on the road or traffic ahead.

Driving in today’s traffic requires skill and concentration, especially in a heavy RV or RV trailer combination.  Part of that skill requires reliable input to correctly anticipate your next move.  In most cases flashing headlights have no definitive meaning, but caution should always be exercised when such signals are present.  Don’t add to the confusion by flashing your lights for anything other than the I.C.C. for passing large vehicles and to warn of a hazard ahead for oncoming traffic.

So, what’s your take on the flash frenzy of the roadways today?   Have you ever experienced an issue for the good or for the bad when you have observed this method of on road signaling?

With A Flashing Thought   -    Lug_Nut     -     Peter Mercer

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37 Responses to “The Headlight Flash. What Does It Really Mean”

  1. Don on August 19th, 2010 4:28 pm

    I haven’t found a way to flash my RV headlights because it has the constant driving lights!

  2. Dalton Tamney on August 19th, 2010 4:40 pm

    When I was learning to drive in the Fifties flashing your lights at night was a way of telling the vehicle in front of you that you intended to pass them. Sometimes they would also flash their lights as an acknowledgment. Today it seems there are a number of possible messages this is meant to convey. Without knowing the “code” they could be misinterpreted and lead to confusion or possibly something more dangerous. I don’t do this.

  3. Tex on August 19th, 2010 4:41 pm

    Lug_Nut, Very well-thought out and interesting article. I agree that we RVrs should concur on a set of uses of the headlights, much as we concurred on a common CB channel for RVrs many years ago. Your two uses are absolutely fine, but I would add one more headlight flash to expect. It’s this: when a professional driver is overtaking me in his semi, I usually flash when it’s clear to come back into my lane. The ritual is usually for the trucker to say “Thank You” by flashing his trailer lights after he comes back to the right. However, when I overtake a truck and try to do that in my motor home, I can’t isolate my rear lights, so the headlights come on too. My suggestion is to do the Thank You flash whenever an overtaken vehicle flashes you that it’s OK to come back to the right lane.

  4. Barbara on August 19th, 2010 4:43 pm

    When we bought our first motorhome, we were told that the flasher was to be used to let large trucks know when it is safe to pull back over in front of us as they pass. On our 2004 coach, the switch to flash was labelled “ICC”, but on our 2009 Dutch Star, there’s just a momentary switch that reverses whatever setting the lights are on when depressed – so we actually have to repeatedly click it to make the lights flash (we always drive with out lights on). We routinely flash to let passing trucks know they are clear, but I don’t get the sense that the truck drivers really care – they come back over when they are ready, regardless of whether we flash them clear or not. We’ve not used the flasher for any other purpose.

    Barbara and Tom
    Newmar Dutch Star 3623

  5. Gary on August 19th, 2010 4:50 pm

    I know that truckers used to appreciate the flashing of your lites to let them know that they were”clear” and it was ok to move back over after passing. That was when you had to turn your lites off and on. The flashing aspect certainly makes that easier. Don’t know if they really care anymore, seems the practice has waned. Too bad. Could use that for all vehicles now. But, road manners have disappeared along with common courtesy and following the rules of the road. Driving is so defensive now and that reduces the fun of driving. People need to learn that yellow signs are advisory only. You can exceed that posted limit. RV drivers, NO!! Follow the signs. You will be safer. And so will I

  6. Jock Bliss on August 19th, 2010 4:53 pm

    Just recently a car coming up in the passing lane behind me flashed his headlights — so I believe he was letting me know that he intended to pass. I had already turned on my directionals to indicate my desire to pull out and pass a slow moving vehicle in my lane. So I turned off my turn signal and waited…and waited…and the person flashed his lights several times again…and was obviously slowing down.
    So he was actually telling me that he saw my original intent, and he was telling me to go ahead and pull out and pass the slow-miover.
    Really the opposite of what one would expect.
    So, yeah, there’s no possible “standard” for the flashing headlight signal. And based on the American way (everyone doing what they damn well personally please as much as possible), I can’t imagine there’s any way we’d get a “standard practice.”

  7. John Adams on August 19th, 2010 5:09 pm

    re:”I haven’t found a way to flash my RV headlights because it has the constant driving lights!”
    Same problem with my Allegro.
    I make sure my headlights are set for high beam and turn them off.
    Then I have to reach over and turn them on and off to flash the highbeams.
    A real stupid system. In the last 10 or so years, i have never owned a truck or car that would not allow you to flash by just moving the “high beam stalk”.
    On my first trip out, I wondered why I never got the “thank you” flash from any truckers.

  8. Bill Dow on August 19th, 2010 5:28 pm

    For those who can’t flash their clearance lights, I have found two methods that truckers often use in place of that. First is to flash your four-way emergency flasher one or two times as an acknowledgment. Second (which is easier and in my opinion safer) is this: After passing and returning to the right lane, when you shut off your right turn signal – flash the left turn once and then the right turn once as an acknowledgment.

  9. Lisa T on August 19th, 2010 6:19 pm

    In Europe I’ve seen overtaking drivers flash their lights on the Autobahn as a way to say “Outta my way, I’m speeding through!”. Here in the States, a headlight flash to a trucker (or motorhome, etc) signaling a lane change could mean “I’m slowing down, come on over”. I do like the way the Europeans hit the flashers when hard braking to mean “hazard ahead”. I’ll turn the flashers on when moving over for an emergency vehicle. It seems to make more of an attention getting impact for cars following.

  10. Rick Burch on August 19th, 2010 6:22 pm

    In Europe the flash from behind has a little different meaning, there is either an emergency in thier vehicle or your driving too slow and slowing the other vehicles down and want you to get out of their way. If it is an emgency normally a cloth is fluttering in the wind.

  11. catchesthewind on August 19th, 2010 7:54 pm

    Dont care what they do in Europe. The word over here is–SITUATIONAL AWARENESS–. Since there is no standard, as with Mr. Bliss, signal your intentions and see how other traffic responds.
    As for me I flash my headlights when I pull out to pass far enough behind to see the mirrors of the vehicle im passing. When an 18 wheeler or large class a or any body that signals I will activate my high beam until they return to the lane im in. As a rule of thumb I use the same signals the truckers use pretty well to good effect.

  12. Liz Bard on August 19th, 2010 8:00 pm

    My dad was an independent truck driver back in the 1950’s, so he taught me the flashing headlights coming toward you mean “you have your high beams on, please dim them.” He also taught me if a trucker is passing you and trying to get back in, to flash the lghts so he knows he has cleared you.

    In the late 1970’s when we were all using CBs, I was racing from Ohio to Texas for a family emergency. A trucker heard me telling someone I was married and in a hurry. He invited me to lunch at a truck stop. He was my dad’s age and wanted to compliment me on how I turned down the party guys. It gave me a chance to ask about the flashing lights since I had been doing it for the truckers who were passing and trying to get back in when it was raining a gully washer. He said at night or when it is raining really bad, that letting them know they have cleared your vehicle is very helpful. They can see you in the daytime, so it is during the evening or inclement weather that the flashing lights are appreciated.

    I use the light switch to turn the brights on briefly. Now to really age myself, my first car was a 1955 Chevy 2 door and you turned the lights on by pulling a knob out on the dash. To make the brights operate, you had a button about the size of a quarter in the floor (more like up on the quarter panel not down on the floorboard) and you had to push it down to hear a click to turn on the brights, then push it again to click to turn the brights off.

    When I was in Germany and just learning to drive on the autobahn, I was in the right lane and I would get the flash of lights in the rear view mirror of our 1972 Opel Manta (with American catalytic converter, 4 cyl standard transmission) the car passing me was usually a Mercedes Benz coupe with a little old lady or man behind the wheel doing the “go granny, go” speeding. I felt comfortable up to 80 mph to drive. I was riding with someone who was doing 100 mph and just had to look elsewhere.

  13. butterbean carpenter on August 19th, 2010 8:22 pm


    I know this because I drove trucks and always ‘flashed all-clear’ for others.. Over
    the CB I heard some say “Get way ahead of him, he’ll brite-lite you.”, so I stopped
    using my hi-beam… You can use your turn signals, though…
    In the ’50s the Jaycees tried to start a campaign for using the flashers when an
    obstruction or dangerous situation was behind you…you turned on the flashers for
    a mile.. This made sense, but never did catch on much.. I still use it, though..

  14. Julie Rea on August 19th, 2010 8:30 pm

    When travelling on crowded interstates, and passing semi’s, I have had a number of them flash their lights when I had safely cleared. This has been greatly appreciated, even on sunny days – sometimes glare in the mirror or backup camera can make seeing difficult.

  15. Dennis Anderson on August 19th, 2010 9:00 pm

    Dad was a truck driver in the 50’s. His routes covered mountain roads in the west. When I got a chance to ride with him ,once in a great while someone in oncoming traffic would flash their lights at him in broad daylight. Sure enough, a mile or two down the road we’d pass an accident or other traffic obstacle. He was always glad that other people on the road warnd him by flashing their lights.

    In the 60s we drove cross-country many times. It was always nice to be near truckers that flashed their lights to let us know when it was safe to pull back after we passed them.

    We miss those days when flashing lights really meant something.

  16. nnedtono on August 20th, 2010 7:39 am

    Because I learned to drive in the 50’s, I also was taught to be courteous to other drivers . The advent of light flashing to help other drivers (except warning of speed traps) was my normal way of driving. Different ways of driving have changed my attitude lately. It seemed that when I flashed the lights to signal somebody to make a left turn in front of me was met with a blank stare of confusion. Other times they would hesitate and wait until it was to late to pull out nearly causing an accident. So now I don’t signal anyone, your on your own. When a semi driver flashes to signal me to pull in front of him, after I’m in the right lane I give him a quick signal by one or two flashes of the left signal light and then the right and let it go at that.

  17. Geoffrey Pruett on August 20th, 2010 9:52 am

    Have the marker light flasher on our current Gulf Stream A which I use to indicate clearance to pull back in, some reply, some do not. Wondered why until a commercial driver in a group I belong to said that like many polite driving practices the attorneys for the insurance industry loused it up. Just like the steering stops on my current Astro van, created by proffesional fault finders to try and provide a way to dodge legal responsibilty for incompetent drivers, the engineers design, the attorneys destroy. Will not stop me from flashing my clearance lights particularly in poor visibility conditions as freeway driving with a triple trailer has enough hazards already. Since I drive at “retired” speeds, truck speed or slower in blustery conditions being passed is a normal thing. The worst thing about trucks passing is the cab over style, quite a bow wave jerking the wheel with those units, long nose are less sudden. When I started driving in the 50’s we used to go on the 2 lanes from Portland to Spokane and Boise and the long haul drivers were very good about flashing to tell us it was alright to go by and have been returning the favor ever since.

  18. Gene0 on August 20th, 2010 12:02 pm

    Besides being an RV’er, I drive a 45′ Motorcoach part-time. I always ‘flash’ passing trucks back in. Most respond, some don’t. Seems like the least likely to respond/reciprocate are the largest carriers (which suggests corporate policy forbids the practice, perhaps coming from the liability standpoint). Most smaller lines and independent owner/operators still abide by long-ago established rules-of-the-road.

  19. Keith on August 20th, 2010 4:51 pm

    I have been driving for nearly 55 yrs and it use to be you flashed your lights to let some one know you were going to pass. If you were meeting some one it meant police ahead or some obstruction on or near the road and you should slow down. Even if people thought you were flashing because of police it served the same purpose and people slowed down for a while.

  20. Barry & Monique Zander on August 20th, 2010 7:12 pm

    Dear Lug_Nut,
    When I was a little boy in the ‘50s riding in the back seat of our car, my father often used his flashers for many of the reasons you listed. I still flash my brights as a signal when I think it’ll mean something to another driver, like “It’s okay to pull into my lane ahead of me.” I want to add another dimension to the subject. I learned early-on in my driving days, probably from my dad, that two flashes means “Warning: Problem Ahead,” and three flashes means “Imminent Danger.” I think anyone would realize you’re trying to deliver a message when you flash your lights more than once.

  21. Barry S on August 20th, 2010 7:57 pm

    It seems to me that flashing lights to inform truckers driving a rig with no trailer might be a waste of time because they are (or should be) well-versed in estimating the distance required to pull back in front of me after passing. It would seem that flashing your lights to a trucker pulling an incredibly long rig with a long trailer would appreciate flashing lights since there is a greater amount of skill or depth perception required to know when to safely pull extra-long rigs back into the forward lane after passing.

    Any ex-truckers on this site who can comment on when to flash or not flash?

  22. Lug_Nut on August 20th, 2010 8:18 pm

    ■Barry & Monique Zander, Great input from all the posters. Yours is very interesting, however, I don’t know how everyone would know this. Thanks for your great input on this topic.

  23. Herb Jones on August 20th, 2010 10:22 pm

    Hi, many years ago it meant it was clear to pull in for heavy haulers especially in bad weather. To this day, I signal truckers they are clear to pull in in front of me. To this day, the professionals all give me a flash of signals lights thanking me, Respect is still recognized! Herb and Ardy

  24. Larry on August 20th, 2010 11:33 pm

    I was, until I retired 2 years ago, a truck driver. On the subject of flashing your lights, in the daytime in clear weather, the flashing of your lights wasn’t really needed, but I didn’t mind. I’d respond with my trailer lights most times, but at night I would rather cars & RVs didn’t unless they could turn them off and then right back on. What I really hated was when cars or RVs (and trucks too) used their high beams for this purpose. Like one poster said above, it lit up the whole inside of my cab, and just when I was peering intently into my right hand mirror checking for pull in clearance, they’d hit their high beams right into my dark adapted eyes thereby blinding the heck out of me. I’d see large green spots for five miles or so afterwards. Those halogen headlights are bright enough to knock your eyes out. My advice to you if you are driving one of those vehicles that have the headlights on permanently is to just do nothing in this situation. I have hated halogen headlights ever since they were invented because of that and people who won’t dim their lights when meeting another vehicle at night, especially on two-lane roads. They need to be dimmed at least a half mile away when meeting another vehicle at night. I realise a lot of people don’t have a concept of what constitutes a “half mile” in distance, so try it this way: when approaching headlights appear to be a single light, the vehicle is a mile or more away. When the approaching lights visibly separate into two distinct lights is approximately a half mile. A quarter mile is when you can see motion or closer. On passing at night on a 2 lane road, if the lights have separated into two distinct lights, it’s not safe. You don’t know how fast the approaching car or truck may be traveling. Another thing on headlights: get your headlights adjusted once a year or sooner. I don’t know how many cars I have met that had one or both headlights out of adjustment, with one right in my eyes and the other so far to the right as to be useless. I met one one night that had one in my eyes, so I flashed my brights at it and the driver hit his dimmer only to have the other one in my eyes instead! It’s usually cars that have the headlights adjusted too far up or they have something heavy in the trunk or some heavy people in the back seat. LOL I see a lot of pick-ups pulling a travel trailer with too much tongue weight jacking their lights up into oncoming traffic eyes. If you’re going to be pulling a trailer, get your lights adjusted, and on a night before you leave on your trip, go to some building where you can shine your low beams on it’s wall about a hundred feet away, mark the spot where both lights hit, then go hook up your trailer and come back and do it again. If your lights are higher on the wall than before, then you need to install load leveler shocks on the rear or adjust your tongue weight lighter or whatever you need to do to get those lights in the same place as before or just don’t drive at night. I grew up in the fifties and I have learned to my sorrow that common courtesy, like common sense, is not so common these days….

  25. Larry on August 20th, 2010 11:44 pm

    Hello. This is Larry again. I justt thought of something else: As far as I know, the headlights are not adjusted at the factory. They just stick them in as the car comes down the assembly line, so you need to get them checked as soon as you aquire a vehicle be it new or used. I have noticed that most well adjusted headlights that I meet are on a police car or a big truck. I see far fewer out of adjustment on semi’s because the drivers are usually diligent about adjusting their headlights. If some of you reading this know for a fact that headlights are adjusted at the factory, post it here. I’ll bet there are a lot of people out there like me that don’t know for sure.

  26. Lug_Nut on August 21st, 2010 5:17 am

    Larry, Thank you for for posting your knowledge on this topic. The headlight adjustment is also very interesting and may explain some of those extra bright lights. Thanks for your great input.

  27. Art on August 23rd, 2010 8:18 pm

    Yes headlights are adjusted at the factory…………………it is just one of the many FMVSS (Federal Vehicle Manufactures Safety Standards) that are required my all vehicle manufactures, including motor homes manufactures.

  28. Art on August 23rd, 2010 8:23 pm

    Woops, I miss typed…………….It’s FMVSS, Federal Motor Vehicle Safety Standards

  29. Rich on August 23rd, 2010 9:15 pm

    The idea that I should not flash my lights to warn of a “speed trap” is ludicrous.
    Is not the purpose of the police car in the median to get traffic to slow down?

    The flashing of my lights to warn of a “speed trap” gets drivers to do just that.

    Unless the cops are there to generate revenue, instead of slow down traffic.

    Perhaps that is the real reason they are there. Other wise they would sit in the median with their lights on instead of hiding by the bridge support in an unmarked car!

    I want to puke when I see expensive Ford Mustangs and Chevy Camaros all decked out in cop equipment.

    They should be patrolling for real crime instead of picking the low hanging fruit.

    And no I haven’t had a ticket in over 25 years because I set the cruise control and forget it.

  30. Haf Canadian on September 2nd, 2010 3:23 pm

    Larry, you should write an article on the subject for Good Sam Club’s Highways publication.

    I spent a lot of time composing my own commentary here, but for whatever reason it didn’t like the captcha code I typed, lower case/upper case, I dunno. And it erased my entire piece. So in disgust I won’t write it again, except to ask if the number of flashes, one or two or more, means anything.

  31. Wendy on September 15th, 2010 1:58 pm

    I live in WA State and got pulled over for “flashing” my lights at the car in front of me. I was not actually meaning to do that thou. I was trying to turn on my wippers which being in my husbands car are on the opposite side my own car has them on. I was informed by the officer that in WA it is illegal to flash my lights. After explaining myself he did not give me a ticket much to my relief.

  32. Lug_Nut on September 15th, 2010 5:41 pm

    Wendy, Great input. I will bet most people are unaware of this. Thanks for your input.

  33. wfree on January 14th, 2011 9:27 pm

    light flashing goes back the 30’s & 40’s. It was developed by the truck drivers of america. and adapted by the automobills of america before freeways came to use. Most roads were two lane. The use of turning your lights off and back on also was used in the same way.
    1 vehical behine you you would signal (flash) the road ahead was clear to pass.
    2 Vehical passes you signal (flash or light off light on) once they are clear of your vehical.
    3 On comming car only one meaning signal (flash) your dam lights are on bright turn them down.
    There are more signals but i dont have time to explaine. This language is not used much anymore most drivers that know it have pass or live way out in the country, cit;y people most likly would not know any of this. Hope I’v help yall

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