By on March 4, 2015

2009 Chevrolet Traverse. Image: Chevrolet

TTAC Commentator MWebbRambler writes:


Your recent Piston Slap on HID lights reminded me of a problem I had with replacing tail lights on my wife’s 2009 Traverse. One of the OEM bulbs burned out, so I decided to replace both brake/tail lights with LEDs.

The LED lights worked great and were brighter than the OEM bulbs, but there was just one problem–the turn signals would blink rapidly, just like they did with the burned out bulb. After I went back and RTFM I learned the rapid blinking or “hyper-flashing” occurs when a bulb is burned out OR the system is drawing little to no current. Since the LEDs use a lot less power, the system thinks the bulb is burned out.

A quick check online indicates my only option for the Traverse is to install a load resistor kit, which requires splicing the wires and adding a load resistor to each bulb. The process looks easy enough, but seeing how you are a lighting aficionado and a wizard when it comes to all things automotive, I thought I’d seek your advice on options.

Sajeev answers:

We covered this before, but things have changed: most, but not all, LED retrofit bulbs (especially of the flashing variety) are unsafe and super illegal. Luckily we have Daniel Stern ([email protected]), brilliant Lighting Consultant, amongst our ranks to clear this all up.

Daniel writes:

That’s an understandable idea, but in most cases it’s presently somewhere between difficult and impossible to do safely, effectively, and legally for reasons much bigger than the improper turn signal flash rate.

The big majority of LED bulb retrofits for cars is unsafe, illegal junk from a variety of vendors making tall yet bogus claims. Odds are that’s what you bought and installed in your wife’s Traverse. They might have appeared brighter to you, but they very likely didn’t work safely. The federal and international safety performance requirements for vehicle exterior lights are much more stringent and exacting than just lighting up in a particular color. The intensity for each function has to be within the proper limits through a large range of vertical and horizontal angles, the ratio between bright and dim intensity must be correct for combination brake/tail and park/turn lamps, and the lamp’s effective lit area must be at least a certain size. These requirements are in place to guarantee an immediately, unambiguously recognizable signal to observers at any angle to your vehicle, day and night, in any weather. Whether these requirements are met can’t be judged by peering at the operating lights; we humans aren’t equipped to accurately assess lights’ performance by eye (it just feels like we are). Most LED retrofit bulbs on the market for vehicle lights, when measured objectively, badly fail most or all of the requirements. Some of them are brighter than stock at certain angles, but that’s not even close to adequate.

Moreover, the light output of an LED drops as its temperature rises, which happens quickly when the LED is lit up. LEDs need effective heat sinking, and the vast majority
of vehicle LED retrofit bulbs on the market don’t have it. This means the retrofitted lamp’s output, even if it starts out adequate with a cold bulb, quickly drops below the minimum requirement with extended use of the lamp (such as when sitting with your foot on the brake in traffic). The poor objective performance of most LED retrofits means the lamps’ output goes from inadequate to very inadequate.

“Gimme a break, you dweeb!”, you say, “I drive with my eyes, not with lab equipment; it lights up red and I think they’re bright enough”. Sure, but your car’s lights are life safety equipment. They have to work the way they’re supposed to –as measured objectively, not by guess and by gosh. If you’re involved in a crash and your car’s safety equipment is found to have been modified, you can quickly wind up in very deep legal doo-doo and debt.

Then we get to the issue that prompted you to write in for help: because LEDs don’t draw the amount of current the vehicle’s turn signal circuit was designed for, they are detected as a faulty bulb. Another safety requirement is that a faulty turn signal bulb must substantially change the flash rate, so the driver will know to fix it. Old vehicles with a standard 2- or 3-prong plug-in turn signal flasher can have a “heavy-duty” flasher installed; meant for trailer towing, these flash at the correct rate without regard to the current load. But most vehicles made in the last two decades don’t use those standard flashers. You might be able to buy a trailer-tow turn signal module for your vehicle, or have its body computer reflashed for trailer-tow mode to cancel the bulb outage indication. Or you can hack your way around the problem by installing “load resistors”, but now you’ve eliminated the low-power benefit of LEDs and you’re cutting wires and adding potential failure points, especially if you use off-brand parts not built or tested to automotive levels of reliability — minimize your odds of a failure by using reputable-brand parts, and forget those crunch-type/Scotchlok wire taps, use Posi-Taps instead.

Don’t wear a permanent frown about this wet-blanket reality check, though. The world’s first legitimate LED bulbs for retrofitment of incandescent vehicle exterior lights came to market last year from Philips — their “Vision LED” line focused on maximum lifespan and their “X-Treme Vision LED” line focused on maximum output. They’re easily available and not very expensive. Right now the Philips X-Treme Vision LED range includes red bulbs to replace 1156 (or European P21W), and 1157 (Euro P21/5W), white bulbs to replace 1156, and white bulbs to replace 921 in reversing lamps. The Vision LED range adds red 74403157 (P27/7W), and 7443 (W21/5W), and white 194 (168, W3W, W5W) bulbs.

The Philips items have a great deal of engineering and development work behind them, and are enormously more likely to work appropriately than anything else on the market right now. But even with these you’re not necessarily home free; they aren’t a “go” for just any lamp that happens to take a bulb type included in their product line. Each and every vehicle light, no matter how simple it might look, is optically engineered to collect, focus, and distribute the light from one particular kind of light source. Changing to a different kind of light source is like putting on somebody else’s eyeglasses; it’s an optical mismatch. Because the light distribution of even today’s most highly engineered LED retrofit bulbs isn’t the same as the incandescent bulbs they’re designed to replace, the only way to know if the retrofit works OK is to test it objectively.

Philips has a website where they list the applications that have tested out acceptably for their various LED retrofit bulbs. The list isn’t exhaustive, because it’s really not possible or practical for them to test each and every make, model, and year of vehicle to be found on American roads. Newer and more popular vehicles are naturally tested first; older and less popular ones are naturally tested sometime between eventually and never. If your particular vehicle isn’t on the approved list, it means either the LED retrofits don’t work safely in your vehicle or your vehicle’s lights haven’t been tested with the LED retrofits. The safe assumption if you drive a recent-but-not-latest model that’s absent from the list is that it flunked the test and you’d best run standard incandescent bulbs and keep waiting.

It’s a little ironic, but the older the vehicle, the more likely the retrofits are to work acceptably. Starting in the mid-late ’90s, exterior lights were designed with
complex-surface reflector optics to create jewel-like effects with completely transparent cover lenses. Bulb characteristics are extremely crucial to these optics’ ability to produce an effective light signal, and in most cases even the best of today’s LED retrofit bulbs won’t work well. Before that time, most vehicle lights used simple, standard parabolic reflectors and pillow or fresnel lens optics; barring a weird bulb entry angle into the lamp, the Philips retrofits work great in many such lamps. Pay careful attention if you try it, though, and make sure they do everything they need to do. There are lamps that wrap around to the side of the vehicle and use a side-on view of the bulb for the sidemarker light function; in many cases using an LED bulb leaves these lamps totally dark from the side. Sidemarker lights do a great job of reducing your chance of being sideswiped or T-boned; it’s foolish to delete them. And be mindful of matching the bulb color to the lens; using the available cool “6000K” white LEDs behind a red lens produces a weak, pinkish-brown light that’s neither bright enough nor of an appropriate color, for instance (though the white LEDs can give a nice bright yellow color in an amber turn signal housing).

More LED retrofit types are in the pipeline from Philips, and over the coming years some of the other reputable makers will produce this kind of product, too. At a recent vehicle lighting technical symposium in Germany, a major lighting supplier showed progress toward truly universal LED retrofit bulbs that emit the right amounts of light in the right distribution, same as an incandescent bulb, but they’re not yet ready for market. Be patient and cautious, because progress will come in fits and starts, and a reputable name doesn’t necessarily mean a product safe and worthy to use; Two brands widely sold on the American market have recently released LED bulbs that don’t even come close to working safely or legally in any lamps at all — sheesh, anything to make a buck!

A final note a little tangential to your original question: the headlamp “LED bulb conversions” now flooding the market are not a legitimate, safe, effective, or legal product. Just as with “HID kits”, these are a fraudulent scam. They’re not capable of producing even a fraction of the amount of light produced by the filament bulb they supposedly replace, let alone producing it in the right pattern for the lamp’s optics to work — see a particularly ambitious amateur test here. This, too, might eventually change; the same company that makes the world’s only legit brake light LED retrofit bulbs also has a first-generation fog lamp LED retrofit bulb that works surprisingly well in certain specific fog lamps.

[Image: Chevrolet]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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46 Comments on “Piston Slap: Traversing the World of LED Retrofit Bulbs!...”

  • avatar

    LED don’t produce heat and therefore give you no help melting ice.
    Usually safer to go with OEM.

  • avatar

    Good read, and informative – think I will throw a link to this for my fellow car wingnuts who go bat-guano crazy for LEDs. I’m sure there will be plenty of contradictory testimonial from the “experts” (and by experts I mean people who are considered “leaders” in the field because they have changed a light bulb in their house successfully).

    I knew about the issue with needing a properly designed reflector and lens but didn’t know LED performance dropped off rapidly with heat build-up.

    Also good info to know if I’m ever involved in an accident with somebody who has festooned their vehicle in LEDs.

  • avatar

    Sajeev, thank you times infinity for involving a true expert on lighting related questions. There is a lot of bad info out there and Mr. Stern knows his stuff, and wont take any crap.

    With the proliferation of inexpensive, ineffective and illegal lighting mods, sound technical information helps make good decisions. I’ve consulted Mr. Stern a few times and he really helped me maximize my lighting and not have to worry about blinding or non-compliant lighting.

    • 0 avatar

      I wish I knew more people like Mr. Stern, I’d be a far less stupider person for it.

      I hope to one day show off my latest project that he’s helping with, relating to the lights in my Mark VIII.

    • 0 avatar

      The problem of blinding oncoming traffic is high on my list of pet peeves.

      I’d be surprised if 1 in 100 of the people who lift their trucks give any thought to adjusting lighting. Likewise, using fog lights during daytime for visibility isn’t a problem, but using them at night when there’s no fog for a hundred miles ought to get you pulled over for an educational conversation, to say the least.

      • 0 avatar

        Still not as bad as those who drive around with their high beams on all the time.

        • 0 avatar

          Is that a thing? Do people really cruise around with the high beams intentionally on?

          • 0 avatar

            @ralph, I dont think it’s intentional so much as plain old stupidity. There really are people out there on the road who don’t know what that bright blue light symbol thingie on their dashboard means.

          • 0 avatar

            My wife learned to drive in a very large city, where you NEVER use your high beams. There was always traffic and/or lighting, so controlling the lighting on the car was something you could skip in favor of collision avoidance and route planning (which are things she is very very good at).

            We’ve been together for about 8 years, and she finally uses them when we’re passing through miles of inky darkness.

            But there’s more to it than that. I learned to drive it the mountains of Appalachia where, if you could see an oncoming car, you’d best have your high beams off. We now live in the Midwest where high beam usage is far more nuanced, since you can sometimes see an approaching car a mile away on the opposite side of a divided highway. It’s more about estimating when the other driver needs you to turn off the high beams for their safety and sanity.

          • 0 avatar

            I always feel like such a jerk when I’m going down an undivided two-lane and I pass an entire convoy of cars before realizing my high-beams were on the entire time.

  • avatar

    I have to say there’s a lot more to this topic than I originally thought!

    Recently I started replacing lights in my house with LEDs because the cost has come down within range of many CFLs. When the tail light went out on my wife’s Traverse, I thought if I swap the lights out with LEDs, I won’t have to change them again as long as I own the car. Plus they did “appear” to be brighter which I thought would be safer for my wife and kids.

    When I encountered the hyper-blinking, I immediately went back to the OEM bulbs. Safety and reliability are my main concerns with my wife’s car and I wasn’t about to get cute with fancy lighting. Now I’m doubly glad I did after reading Sajeev and Daniel’s advice.

  • avatar
    Felix Hoenikker

    This is a great article and validates my automotive bulb replacement practice. I just look up the OEM bulb number that burned out and replace it with the exact same thing. Cheap, fast and easy.
    Don’t overthink the solution.
    In an aside note, I did eliminate the Nissan Altima from my shopping list last summer when I discovered that the bumper needed to be removed to change a headlight bulb. WTF kind of crap is that. I think the salesman was a little shocked when I opened the hood and asked where the fasteners for the headlights were. The sales manager sheepishly came out to explain that the shop could replace the bulb in about an hour’s worth of labor. I replied that it takes me no more than 15 minutes to replace the headlight bulbs on the three cars we now own, and bringing the vehicle into the shop to replace a bulb was unacceptable to me.
    That’s part of the reason I ended up with an Accord

  • avatar

    This made me wonder about folks who mask or tape over their lights or “aesthetic” purposes. The people who like to tint the entire light cluster to make it blend into the bodywork or leave only a tiny stripe exposed.

    I’d like to think that this rates higher on the law enforcement radar than a busted bulb, but does anyone know if LE does any enforcement on this?

    • 0 avatar

      Worse are those who tinted their headlamps to “look cool”. I knew someone that did this with a Ram 1500 back in 2002 and I asked him “doesn’t this reduce your sight visibility at night?” His response was “I just drive with my high beams on all the time”

      I must have had quite the dumbfound look on my face when I thought “REALLY????” Why do people think it is cool to blacken out lights???

    • 0 avatar

      I see way too many ricers driving around with yellow head lamps or foiled over headlights to think LE gives them any kind of harassment. You must remember your typical cop knows way less about the law than an informed well read citizen. Standards have dropped even more over the years. Why a cop can be given a badge and gun with 20 college credits in liberal arts is beyond me. I doubt LE knows much more than a headlight is burned out.

      Remember cops don’t feel the need to know the law when 99% of sheeple never question them. For example, a question such as “Do you have any weapons in the vehicle” during a routine traffic stop is a completely legal question to ask in the State of Florida but not in New York State.

      Adding insult to injury is when you politely remind the officer of the law and he proceeds to take it as insult and write you every fine he can.

      • 0 avatar

        “Adding insult to injury is when you politely remind the officer of the law and he proceeds to take it as insult and write you every fine he can.”

        … or worse.

      • 0 avatar
        Nick 2012

        20 college credits? Is policing open only to members of the Tzarist intelligencia?! Indiana’s proletariat friendly policing approach only requires a 40 hour course, with a substantial 24 hour period of classroom training. I spent more time training as a cashier at Kroger in high school. Obviously state police and most cities won’t let you near a badge with only the 40-hour course, but get into rural parts of the state and this is common.

  • avatar

    The other important thing to remember about “simply” installing a load equalizer to resolve the voltage disparity between incandescent and LED is the heat build-up. When sitting at a stop light with brakes applied or turn signal on for even 1 minute, there can be a risk of fire on a hot summer day. The load equalizer essentially absorbs the additional voltage not needed by the LED bulb as heat. This heat build-up will eventually melt the load equalizer and catch on fire.

    I initially got excited about LED replacement bulbs but quickly realized that the horizontal projection of the light drops off rapidly and is ultimately unsafe.

  • avatar

    I drove the 2014 Corolla with the LED headlamps… and honestly, I was not all that impressed with the lighting output. I actually found them to be a lot dimmer than my halogens… I could have been the sharp cut-off that you get with projectors… not sure. Acura’s version seems a lot better, but what I wonder is how efficient these lights really are in winter climates. At least with Halogen bulbs, there is a fair amount of heat build up that helps to melt accumulating snow over the lens.

  • avatar

    I would welcome the hyperflashing… I think the flash rates of most cars is too slow as it is. You get one blink and then the car is in the other lane already. My old motorcycle got retrofit with LED turn signals with a higher flash rate and it became much more noticeable.

    LED retrofit brake lights on the other hand seem like a bad idea if the fixture doesn’t include a pretty good heatsink… The LED boat trailer brake kits are a godsend though. It has lasted about 4x as long as any other set so far.

    • 0 avatar

      That’s because most drivers are too LAZY to hold the turn signal indicator down for more than a quick moment. Way back when driver’s ed actually TAUGHT skills, it was: began to signal, make the change, and then stop signalling once the lane switch was completed….but then I’m dating myself!! :-)

      • 0 avatar

        Sadly, around the northeast, you don’t want to signal a lane change too early, because most people will take it as a challenge and see if they can move up and block you.

  • avatar

    LED conversions can work acceptably in interior lights, which have neither the strict regulatory requirements nor extreme environmental conditions of your indicators. I found an LED retrofit to my dome light and reading lights produced a much brighter, more usable light than the fairly mediocre incandescents. Outside of the car, though, even the puny license plate lights were better served by standard automotive light bulbs.

    • 0 avatar

      Yeah, when I lost a dash bulb in my F250, I just put in a full LED replacement set.

      But, like you say, different application, different requirements, better fit.

  • avatar

    Lots of LED taillamp retrofits are terrible. They neither produce high enough light output nor project it in a wide enough visibility cone. They look about as bright as a server room switch panel.

    I usually see these on clapped-out pickup trucks because their taillamps tend to be rectangular and simple.

    Nobody can see your cheap lights, bro.

  • avatar
    Nick 2012

    I just want a world where all turn signals are amber. The contrast really helps the brain see what’s happening much sooner than a sea of red blobs.

  • avatar

    My car has not LED tail-lamps, nor LED headlamps, nor LED DRLs, but rather LEDs for the license-plate area. I think that’s just about the most useless application for LEDs that you could possibly have.

    • 0 avatar

      No that is the best application since most people won’t bother to replace those if they burn out. Back in the day Ford put a unique dual filament bulb in their license lights that acted as a back up.

  • avatar

    The reality is most tail lights do not have “reflectors” they often have raw white, grey and occasionally even black plastic. So the focal point of the bulb has little effect on the light output.

    LEDs have been in common use as S/T/T lights in MD and HD trucks for years as well as for some time in cars and are fully DOT compliant and safe. That is not to say that every LED replacement on the market is up to standards but this article makes it sound like the issue is as bad as the HID retrofits for composite headlights that do use a reflector and lens that work together to focus the light.

    As far as the flasher issue, yes many cars now have the flasher integrated into one electronic module or another but that doesn’t mean that you can’t use a flasher designed for use with LEDs. It is usually as simple as clipping the right pair of wires and wiring in a conventional style flasher in of the electronic or HD version.

    • 0 avatar

      “DOT compliant and safe” is a meaningless statement. Feel free to actually read up about that, Mr. Stern covers it rather nicely, if this article itself was not good enough for you to understand why LED retrofits are vast majority of the time unsafe and don’t meet any sort of safety standards.

      • 0 avatar

        Try rereading my comment, Mr Stern’s article makes it sound like LEDs are unsuitable for this application and are patently unsafe which they are not. I did not say that everything you can buy on the market is DOT compliant and safe just that LEDs are a perfectly safe and compliant option when done right and that the whole line about the refelctors and optics is pure BS.

        • 0 avatar

          LEDs are unsuitable for a *drop-in replacement*, is what he’s saying.

          That LED units are used in *dedicated housings* on trucks (or as OEM equipment on cars!) is irrelevant to that, because it’s … a completely different application than a drop-in replacement for an incandescent.

    • 0 avatar

      The reality is reflectors don’t necessarily look like mirrors. Sometimes they’re white. Sometimes they’re grey. And yes, sometimes they’re nonexistent in lamps that have fresnel lens optics, which — yes — are “looking” for a light source at one particular location. The focal point of the bulb always has a major effect on the lamp’s output.

      (Huh, look at that, fresnel lens optics are mentioned right there in Stern’s writeup!)

      Yes, LEDs have been in common use for many years…in lamps designed that way from the ground up. What does that have to do with dropping LED bulbs into lamps designed to take filament bulbs? Nada, zip, zilcharoonio.

      As the hip young persons say these days: “Bye, Felicia!”

  • avatar

    One trick I’ve seen is to replace a capacitor in the circuit that controls the flashing of the turn signal. The system still pulls the lower current and so changes the blink rate, but with the different capacitor, the new blink rate matches the old.

    That said, I generally agree not to mess with such things.

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