By on October 18, 2016

 

third brake light chmsl. shutterstock user Bhakpong

Chris writes:

I’ve noticed various new-ish cars, ranging from Kias to Lincolns, with a flash-then-steady mode on their center high-mount stop lights. Is this becoming standard? I expect it’s not federally mandated, but I can’t imagine where else it’s coming from.

More importantly, how is it being implemented? I’m thinking about grabbing one from a salvage yard in a few years.

Sajeev answers:

Yes, they’re legal not illegal, but no, they ain’t factory. Mercedes tried to bring them to the US — and failed. You can buy the kit for cheap or, more shockingly, as a (high-margin?) add-on sold inside a dealership’s F&I department. I suspect you are seeing the latter in your neck of the woods, as I doubt people would install ’em otherwise.

I first saw a flashing CHMSL on a C5 Corvette at an open track event at MSR Houston. Thank goodness I was the fastest guy in the novice run, so I could pass the obnoxiousness in my trusty 1988 Cougar. That said, I installed sequential signal lights (homage to the original 1967 model) during its mild restoration in the last two years.

So who am I to judge poor subjective taste?

(Sorry again for not turning my potato sideways. I’ve learned much since 2014.)

I reckon these are a box of solid state electronics, much like the sequential kits on the market today. The three wires splice into the factory harness, but I wouldn’t cannibalize one of these kits if you find one in the junkyard. The data on its safety benefits seems subjective and I doubt it’ll stop an Instagraming driver from rear-ending your ride. More to the point: no amount of flashing is more eye-catching than social media, son!

Look, I don’t necessarily practice what I preach. But if the new Mustangs and even Audi implemented sequential signal lights, perhaps I’ll successfully take the higher ground.

Off to you, Best and Brightest.

[Image: Shutterstock user Bhakpong]

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73 Comments on “Piston Slap: To Flash or Not To Flash your CHMSL?...”


  • avatar
    PeriSoft

    I’ve thought for a while that brake lights ought to flash when ABS is triggered (or perhaps when deceleration exceeds some preset threshold like .5g or .75g). Out on the highway that could serve to give an extra second or so warning of serious traffic-crunch half a mile ahead, and thereby alleviate the concertina effect that ends up with some poor bastard a mile back from an incident getting rear-ended.

    • 0 avatar
      energetik9

      I do agree on this one.

      BMWs have a feature where additional brake lights engage under hard braking to create a larger visual footprint. A flash under ABS engagement would be a great visual indicator of the degree of braking ahead.

      • 0 avatar
        Featherston

        I seem to recall a less expensive car’s doing this under hard braking on the Top Gear test track.

        @ PeriSoft – I once was a passenger in a car that almost did the rear-ending in that scenario. The friend behind the wheel is a less pokey driver than I am but generally is pretty careful. I wondered how he could have come some close to hitting someone. The subsequent stop-and-go crawl showed that, yep, the brake lights on the car in front of us were completely out.

        Brake lights are important, people. Give them a check in your driveway every once in awhile.

    • 0 avatar
      heavy handle

      That would work if the US mandated amber turn signals, like the rest of the world. As things stand, it would just created more confusion (flashing = turn signal, but both sides are flashing, so maybe it’s hazards, or maybe it’s something else… at which point you’ve hit whatever was flashing).

      • 0 avatar
        strafer

        It’s not really “flashing” like hazards, but more “rapid pulsating” that grabs your attention.
        Back in 80’s there was similar device called Firefly that would do the same for motorcycle headlights to make them more visible during the day.
        Some were concerned with it triggering epileptic seizures, however…

      • 0 avatar
        Scoutdude

        It is the CHMSL that strobes not the lower brake lights.

      • 0 avatar
        HotPotato

        Euro makers are on my shiznit list for doing all-red taillights for the current and previous generation of US-bound cars. It might look cleaner, but it sure isn’t safer. Return my amber turn signals please.

    • 0 avatar
      APaGttH

      This I agree. I’ll put on my hazards if traffic suddenly comes to a halt on the freeway as an extra, “HEY PAY ATTENTION BACK THERE”

  • avatar
    energetik9

    I wouldn’t do it. Mostly because I can picture how annoying that would be if I were following you.

    • 0 avatar
      vvk

      Annoying is good. That’s the point.

      Having said that, I am annoyed at people using their brakes randomly when simply lifting off the gas would suffice. I seldom use my brakes, mostly relying on engine braking to slow the car. My front brake pads usually last 150k miles or more.

      • 0 avatar
        Nick_515

        tapping the brakes also appears to be a widespread ‘cruise disengage’ strategy. also unnecessarily annoying.

        • 0 avatar
          ToddAtlasF1

          My current car has a nice cancel button for the cruise control that doesn’t wipe out the speed setting. I’ve had other cars though where the only way to be in a position to use the resume feature was to tap the brakes. The only other option was to shut off cruise control and lose the speed setting.

          • 0 avatar
            Nick_515

            I do as well ToddAtlas and thought that was universal. If there is no other way to turn off cruise without loosing the speed setting… that really sucks.

          • 0 avatar
            scrubnick

            I thought this was the case on my Prelude! Turns out, the “cancel button” is simply pressing the faster and slower buttons together.

          • 0 avatar
            Vulpine

            If you have a clutch (manual transmission), hitting the clutch will release the CC as well.

          • 0 avatar
            scottcom36

            Vulpine, not always! My ’15 Civic doesn’t disengage the cruise when clutching. I can shift gears and the cruise stays on. It was a strange feeling at first.

          • 0 avatar
            Vulpine

            Interesting. My Jeep and my Saturn both would disengage cruise if I depressed the clutch. I would think the cruise would race the engine if you let speed drop off when holding the clutch down. Any chance they might have a timer on it that would disengage after the clutch is held for a few seconds? Otherwise, that sounds unsafe, especially if you’re downshifting to reduce speed.

    • 0 avatar
      slance66

      It’s annoying and distracting and will cause accidents in my opinion. The strobe effect is blinding and causes you to flinch and probably close your eyes. These brake lights are the worst thing I’ve seen come out in many years.

      • 0 avatar
        Kenmore

        How ’bout for epileptics? Four lanes full of cars in front of them all accordioning and strobing them with every bunch-up? Like old helicopter blades flashing sunlight.

      • 0 avatar
        Vulpine

        Why do you assume it has to be a strobe? 4-way flashers are not strobes; neither are turn signals. They’re simple blinkers. It’s just a matter of varying the rate of the blink, not “strobing” the lights.

  • avatar
    Vulpine

    Any flashing for the brake lights would need to be standardized… perhaps slow for light pressure or maybe even on steady, then an increasing rate as pedal pressure is added. The old incandescent lamps (still in use on many, if not most, models, simply can’t offer the reaction times to handle a high rate of flashing and would likely burn out more quickly if consistently used at a relatively fast flash. LED lamps react far more quickly and offer a very sharp on/off cutoff.

    Now, personally I liked the sequential taillights such as Sajeev references. I loved seeing them on the old Thunderbirds (’60s) and later Cougars. Some modern taillights, like the ‘racetrack’ assemblies on the Dodges would almost lend themselves very well to such, along with some of the aftermarket light strips you see on some pickup trucks (though placement or something has their brightness questionable at times.)

  • avatar
    Joss

    This is something other than rear fog lights right? Which seem to activate as either just intensified brake lights or park/brake lights.

    • 0 avatar
      heavy handle

      You are correct, this is different from rear fog lights. Rear fog lights are mandatory in Europe, but usually only found on high-end European imports in the US.

      Rear fog lamps fall within the same brightness range as brake lights. They do not flash.

      Formula 1 mandates a similar rear light when a race is officially “wet”. F1 rear fog lamps do flash.

  • avatar
    Car Guy

    It is not legal in the USA to flash the rear lamps. Anything like that is aftermarket.

    • 0 avatar
      tsoden

      Are you sure? BMW’s have this feature and the current and last gen Mustang have sequential turn signals…

      • 0 avatar
        Car Guy

        100% positive. I work in the industry.

        The sequential turn signals are OK as thats a separate function from brakes.

        Sajeev is right – this is a dealer add-on (usually with a huge mark up) that should not be sold on a new vehicle.

        • 0 avatar
          zamoti

          I think you can typically have it enabled if you have the software; I know that BMW EDIBAS can do it, though I’ve never tried myself. I’m sure there are plenty of simple solutions to enable it if it’s just a software bit flip.

          • 0 avatar
            JimC2

            Hmmm… software thing… it would be unfair of me to bring up the permanently on Pontiac G6 brake lights, so I won’t bring that up.

      • 0 avatar
        Pch101

        “U.S. government regulators say brake lights are allowed to do only one thing: glow more brightly than the taillights. Flashing is off-limits. Mercedes did get approval to install the feature on a few cars, as a trial program, but that’s all.”

        http://www.popularmechanics.com/cars/g1195/10-car-options-the-law-wont-let-you-have/

      • 0 avatar
        golden2husky

        The Mustang’s sequential turn signals are not legal for use in Europe; the cars that are sold abroad have this feature disabled…yet you can buy European cars with a switch that keeps one brake light on all the time for better visibility in fog or snow squalls. Of course many American drivers leave this on all the time….talk about annoying.

  • avatar
    ajla

    “… as a (high-margin?) add-on sold inside a dealership’s F&I department. I suspect you are seeing the latter in your neck of the woods,”

    Now I’m sad.

  • avatar
    sportyaccordy

    Flashing is good. Catches my eye for sure, and I know it works with my motorcycle’s headlight.

    What they REALLY need to do is dial back these LED tail lights’ brightness at night time. My retinas are still burnt from sitting in traffic on the Lincoln Tunnel like 5 years ago.

    • 0 avatar
      DenverMike

      The flashing bike headlight goes way beyond annoying. The bikes should be impounded and crushed! I don’t care if it’s legal, they don’t completely strobe OFF, and it’s God himself in assless leather chaps.

  • avatar
    Pch101

    Most of the safety benefit that is derived from the uniqueness of the disco-style center brake lights would be short-term at best as drivers become accustomed to them and learn to tune them out.

    Long-term studies of the standard center-mounted brake lights found that they were ultimately helpful but were less effective over the long run for that reason.

    I wouldn’t bother changing anything out.

    • 0 avatar
      JimC2

      I think the other downside to CHMSL is they were conceived when nearly all the vehicles on United States highways were cars. The SUV craze didn’t really take hold until about ten years later. Pickup trucks got a lot more popular at the same time too. So the idea of seeing through the car right in front of you–be it a sedan, coupe, or vista cruiser station wagon, but all of approximately the same height–well that just doesn’t happen anymore.

  • avatar
    IBx1

    I put one of these on my motorcycle’s LED brake light. The module costs $5 or so, and before I had it I always tapped the brakes a lot before slowing down to flash the light myself. However, in an emergency stop, I need full braking power and don’t have the luxury of time to flash the light before slowing down. Anything that gets me more visibility keeps me marginally safer.

  • avatar
    JimZ

    they have off-the shelf kits for motorcycles. look for “brake light flasher” or “brake light modulator.”

  • avatar
    Kenmore

    Well, now I know what CHMSL really means. I’ve seen it of course but just assumed it was something like YHWH or DKNY that you weren’t supposed to say aloud.

  • avatar
    BriGuy

    Some states have mandated these flashing break lights, such as Nevada. Perhaps other states have as well?

    • 0 avatar
      heavy handle

      I don’t think that states are allowed to over-rule federal car safety standards. They can choose not to enforce some standards, which amounts to the same thing.

    • 0 avatar
      eggsalad

      I live in Nevada. Neither of my cars have flashing CHMSL. In fact, none of the cars I have ever owned have had them.

      Furthermore, only about 5% of the cars I see have flashing CHMSL. That would mean 95% of the cars on the road are operating illegally.

      Can you please cite the Nevada Revised Statute mandating flashing CHMSL?

      • 0 avatar
        eggsalad

        No? Well here’s the most current Nevada Revised Statute, and I can’t find ONE SINGLE THING mandating flashing “break” lights.

        I’m pretty sure that whoever told you this was lying to you. Probably a car salesman.

        NRS 484D.125  Stop lamps.

        1.  Except as provided in subsection 5, every motor vehicle, trailer and semitrailer, and any vehicle which is being drawn at the end of a train of vehicles must be equipped with two or more stop lamps, except that any vehicle manufactured before July 1, 1969, must have at least one stop lamp if the vehicle was originally equipped with only one stop lamp.

        2.  Except as otherwise provided in chapters 484A to 484E, inclusive, of NRS, the stop lamp or lamps must:

        (a) Be on the rear of the vehicle, and if there are two or more than two must be as widely spaced laterally as practicable;

        (b) Display a red, amber or yellow light visible from a distance of not less than 300 feet to the rear in normal sunlight; and

        (c) Be activated upon application of the brake.

        3.  On a combination of vehicles, stop lamps on the rearmost vehicle only are required.

        4.  A stop lamp may be incorporated with a tail lamp.

        5.  The provisions of this section do not apply to towable tools or equipment.

        (Added to NRS by 1969, 1204; A 1981, 622; 1987, 1343) — (Substituted in revision for NRS 484.555)

  • avatar
    suburbanokie

    I’ve been seeing this increasingly, especially on Hyundais and Chevys. In fact test drove an Azera a few weeks ago and every vehicle I could see on the lot had a sticker near the center stop light advertising this feature. That said, I don’t think they should activate below, say, 10-15 MPH. Makes stop-and-go, or being stopped behind someone who likes to creep at a light, really annoying with one of these cars in front of you.

  • avatar
    JimC2

    iPd used to have a hazard light relay in their catalog (remember those??) that would make the *amber* hazard lights blink under hard braking. The ad said something about it being apparently legal.

    This idea seems like a paranoid soccer mom timid driver thing, like arbitrarily turning on your hazard lights in the rain.

  • avatar
    LeMansteve

    As long as the brake lights are all there and functioning, I’m fine.

    Two of my biggest pet peeves are:

    1. aftermarket tail lights with less performance than the OE units
    2. broken or missing tail lights

    • 0 avatar
      CobraJet

      Agree with you. In my area there a lot of old GMT 400 pickups that have aftermarket tail lights. In the daytime the brake lights are almost invisible. At night the tail lights are very weak. These trucks are downright dangerous.

  • avatar
    DenverMike

    Just tap the stinkin’ brakes before stopping. And make it a darn habit of slowing as gradual-like as possible. It’s those jackrabbit starts followed by standing on the brakes at the very last second that leads to most rear end collisions in my experience

  • avatar
    Audiofyl

    I feel like 50% of the Hyundai vehicles In the metro chicago area have this horrible “feature” on their chmsl (maybe 4-5 flashes, led or incandescent, then on solid). Try being in slow moving traffic in rush hour with one of these within your area of vision. I’ve never wanted to gouge my eyeballs more.

    • 0 avatar
      VTECV6NYC

      Too true. When I lived in Chicago, I thought this feature was only exclusive to Hyundai and Kia, as those were the only vehicles that seemed to have the feature. Between that and all of the crap advertising that some of these same drivers allow dealers to install on their rear windows in exchange for free oil changes, I thought it was a gimmicky feature that only made a cheap vehicle look even chintzier.

  • avatar
    dividebytube

    A few years ago I had this idea:

    The harder you brake, the more segments of the brake light turns on.

    Soft-to-moderate braking: outer lights go on.
    Hard braking: outer and mid light goes on.
    full ABS hit: all brake lights go on.

    Something like the current Mustang with it’s sequential taillights would be easy to retrofit.

    Not sure if it would reduce rear end accidents but it may help. For example, is that guy ahead slowing down because it’s icy out… or is he panic braking because he is about to rear end another car?

    • 0 avatar
      Sigivald

      Problem with that is “pressure” isn’t really a consistent thing related to vehicle mass and braking capacity and change in velocity, is it?

      I suppose two modes, “no real pressure at all, just disabling cruise or covering the brake like an idjit” and “more than that” might sort of work.

      But otherwise “medium pressure” and “a lot more”, well, I’m braking pretty seriously if I”m behind them in any case…

      (Also, with some other random car in the dark, how do I *tell* how many segments are left un-lit, especially in a split second decision?

      This solution – and I’ve thought-experimented similar ones to the same conclusion) doesn’t seem like a real-world practical one; too much information, too vaguely presented, more confusing to the average driver, of which half are *worse than*.)

  • avatar
    sckid213

    Here in Los Angeles, I’ve seen the flashing CHMSL on a few current-gen Jeep Cherokees. I honestly just assumed it was a factory defect from FCA. I remember the second-gen (I think) Sebring had a weird issue where the flashers would strobe at all times no matter what – I figured this was version 2.0 of that.

    Had no idea that dealers were installing these as add-ons! Man people will buy anything when they’re trapped in the F&I office.

  • avatar
    dukeisduke

    F&I department is right. I usually see these on Kias, and on the back window of one, there was a triangular sticker touting the pulsing CHMSL. I Googled the company (I admit, I was interested in installing one), and found their whole F&I pitch, and how their unit cost “only five dollars a month” when added to a vehicle. Assuming a 60-month note, that’s Three.Hundred.Dollars for a pulsing CHMSL.

    • 0 avatar
      dukeisduke

      I looked at Pulse’s FAQ page, and it was them that I Googled awhile back:

      Q:IS PULSE EXPENSIVE?

      A. Pulse is fairly inexpensive, typically adding only about $5 to your monthly car payment. The benefit, though, of being able to help protect you and your family from rear end collision is immeasurable. How can you afford not to have Pulse?

  • avatar
    Corco

    I bought a Volkswagen about a year ago that had this already installed by the dealer.

    They tried to charge me $300 for it at the F&I stage, and I told them to take it off, because I didn’t want it. They removed the charge but didn’t uninstall it. I was already getting a great price on the car- 3-door manual transmission gas Golfs weren’t exactly flying off dealer lots post-scandal, so I was okay with that.

    I was nervous about this, but the manufacturer, a company called Pulse, claims it to be legal in all 50 states and Canada. So I have it and just don’t think about it, but I don’t necessarily like it.

    So at least in my case, it wasn’t F&I so much as that dealer installs it on ask their cars by default and then tries to get money out of people for it afterwards.

  • avatar
    Bearadise

    Leave the Cougar running with the garage door open, add some Mannheim Steamroller music and your Holiday lightshow is all set up.

  • avatar
    whitworth

    They should be illegal, only emergency vehicles should be able to strobe their lights like that.

    People will start ignoring police/fire/ambulance if everyone has a strobing brake light.

  • avatar
    Longshift

    I really hope that flashing third brake lights do not become standard. Apart from being extremely irritating in stop-and-go traffic, their blinking gives the false impression that the brake are being let on and off. The steady third brake light is more than adequate; I have never had any trouble noticing it. On the other hand, I have come close to rear ending several cars that had their third brake lights burnt out.

    Another bad idea is those sequential turn signals on the late model Ford Mustangs. It takes several moments to tell that the car is signaling, and it is not easy to notice if I am not looking directly at it. I would much rather see amber turn signals (which should have been standard 30 years ago). With amber, I know instantly that the car is signaling, and I notice even if I only see it out of the corner of my eye.

  • avatar
    tankinbeans

    I saw this for the first time today on a late model white crossover of some sort. I figured it might be goofy wiring, similar to late 90s GM vehicles that light up the amber signals when the brakes are hit. I was getting irritated behind this person because she was doing the morsecode braking on top of the already flashing cyclops.

  • avatar
    zipper69

    Every jackass that is remotely concerned with Public Works around here in Gulf Coast Florida has added strobing white lights within the light clusters of their (mainly) F150/F250 pickups that they either leave on while in traffic (pseudo emergency??)or while parked on the verge as they stop for a pee break or a quick smoke.

  • avatar
    rpn453

    I’ve never seen this, but I have to assume it would cause me to involuntarily turn my brights on for the duration of the time that I’m behind such a vehicle.

  • avatar

    I’ll tap my lights if I think the guy behind me is sleeping, or celling.

    If I come to a full stop in traffic on a moving roadway, and in fear of a tail end, I’ll hit the emergency flashers to break the glaze of the guy behind me…

    Please don’t automatically strobe lights. The only lights that should modulate are front headlights on motorcycles.

    • 0 avatar
      never_follow

      That’s what I’ll do as well. It pays to use your rearview and see whether you have a dozer behind you or not.

      Do they vary their speed with you? Probably paying at least a bit of attention. Does letting off the gas make you worry for your safety? Leave lots of space and be ready to throw on the hazards if there’s an emergency.

  • avatar

    I noticed this yesterday on my soon-to-be father-in-law’s GMC Terrain, as well as most city buses and Disney World buses…

  • avatar
    415s30

    I have seen a brake light on Evos that blink three times when they hit it. I lift mostly until I need to brake, so in SF when its wet I tap my brakes to flash them to let them know. In my 240Z it’s hard to see the small lights, I was thinking of putting an LED tailgate brake light strip on the back of my roll bar so it was really noticeable through the rear hatch glass. I already had someone lightly tap me and my friend’s shop did a lot of work for even a small incident.

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