Automotive History: When Front Turn Signals Changed Colour – Amber Waves of Pain

For many years, starting with the advent of the electric flashing turn signal, the front indicators emitted white light by means of a colourless incandescent bulb behind a colourless lens of one sort or another. This was in keeping with a longstanding colour convention of white for front lamps and red for rear ones. This is an account of struggles toward rectitude in front turn signal specifications—the rear ones will have their turn, but not today.

In 1958, the (U.S.) Society of Automotive Engineers undertook a practical study of turn signals. In case you think that sounds all rigorous and scientific and stuff, it means the SAE Lighting Committee held meetings where they peered at cars equipped with a variety of signal configurations, and committee members voted on which setups they thought they liked best. One of the outcomes was a consensus that front signals ought to be amber, the better to be discerned against reflections off chrome during the day…

(They had a point, there; did you see this ’52 Chrysler’s white turn indicator before I mentioned it?)


…and against white headlamps at night. In theory, this recommendation wasn’t radical and caused no real disruption; in 1957—and probably quite a few years earlier, too, but 1957 is the oldest version I have—the SAE standards for both turn signals and parking lights already specified “white to amber”, a term still in use which means white or amber (as technically defined) or any shade in between. But practically, the push for amber front turn signals in the United States caused some serious friction; giant headaches, vociferous opposition, and dubious marketeering.

At the time, you see, there was no national, nationwide regulation of vehicle equipment, design, construction, or safety performance. That didn’t come in until the advent of the first Federal Motor Vehicle Safety Standards on 1/1/1968. There wasn’t even any legal structure in place for national regulation of vehicles, nor was there any federal agency with the authority to regulate motor vehicles, until the National Traffic and Motor Vehicle Safety Act of 1966 established the U.S. Department of Transportation and three relevant agencies: the National Highway Safety Agency, the National Traffic Safety Agency, and the National Highway Safety Bureau. These three agencies were consolidated into the National Highway Traffic Safety Administration (NHTSA) by the Highway Safety Act of 1970, but now I’m getting ahead of myself; the main thing is it was not possible for the US Government to require or specify anything in the way of vehicle equipment or design. That was left to the individual states, and most of them required type-approval by that state for each and every lighting device to be offered in that state on or for vehicles. And this was without any reciprocal recognition, so automakers had a giant amount of paperwork to do to get all their cars’ various exterior lights approved by each and every state in time for each new model’s first sale. Same for aftermarket repair and accessory parts. (funny, I don’t remember reading anything about this costly, unwieldy, restrictive, perpetual nuisance in the buff books’ screeds and jeremiads against federal regulation of vehicle design and construction).

It wasn’t a complete patchwork mishmash, for there was some coöperation among the states loosely coordinated through a series of associations of state motor vehicle administrators; a series of automaker associations, and (at a distance) SAE. 25 of the 50 states required white front turn signals and/or parking lights, and back then there was a quaint custom of states actually—sometimes theatrically!—enforcing their vehicle regulations. So 25 states had to be coralled, cajoled, and convinced to change their laws. This typical article from the Tuscaloosa News on 24 January 1962 politely elides the enormous amount of sausagemaking involved; it reminds of that scene in “The Great Dictator” when Charlie Chaplin’s “Adenoid Hynkel” character shouts out a bunch of scornful, hateful pseudo-German, then the translator says His Excellency has just referred to the Jewish people:


By and by and by, all the states got onside; amber front turn signals were now legal throughout the land. This, however, was much closer to the start than to the end of the problems. In that era of the annual model change, being seen to have this year’s model rather than last year’s was a very big deal. Legislative catscratches and bites were still being bandaged when aftermarket amber turn signal conversion products popped up like mushrooms on cowflops. One reputable outfit—Peterson Manufacturing, still a going concern making top-notch lights in Grandview, Missouri—offered a product they called AmberTurn. It was a little brush-in-cap bottle of transparent amber paint formulated to adhere reasonably well to plastic and glass. I would like to show it to you, and so would the Peterson people, but it’s missing from their archive and I haven’t found any promotional material (yet; I’ve only been looking since 2015).

So here’s a small sampling of the other offerings. Many of them were flexible amber filter “gels”, as the theatrical-lighting industry calls them, trimmed (more or less) to fit between the bulb and the lens. Here’s a sample ad for probably that kind of conversion:

Others were described to sound like amber plastic balloons to clip onto the bulb behind the lens—this one from the February 1964 issue of The Rotarian claims also to “increase the light magnification”. I’m so sure.

Some were similar to Peterson’s AmberTurn, like this one (Popular Mechanics, April 1963):

And still others were…well, that is a very good question, and they’re certainly glad you asked it! (also from the April 1963 Popular Mechanics):

There were probably a lot of poorly-informed homespun efforts at conversion, as well; orange paint in a spray bomb (as aerosol cans were still known at the time) was as close as your nearest paint or hardware store. But remember that quaint custom I was talking about? You could get a whole lot more than just an actual, real ticket for monkeying with the lights on your car; just wait til you get to the end of this article from the Reading (Pennsylvania) Eagle, 23 March 1963:

(‘What colour is amber?’ was never actually a puzzle or problem in all of this; its technical definition had been established by SAE for decades.)

Arrested‽ Wow, the past is a foreign country. Could wish the same attitude were applied today against the likes of “HID kits” and “LED bulbs”.

There were probably some replacement lenses offered in amber rather than the original clear, such as the ones on this 1960 Pontiac (which left the factory with clear lenses in front of clear bulbs):

Garth Goode photo at the Cohort


But now wait a minute here; okeh, paints and gels and clip-ons and suchlike might have given less-than-good results, but—aside from it being an arrestable offence in at least Pennsylvania—why not just replace the clear bulbs by amber ones, the same 1034As used on 1963 cars with clear lenses? Well, it turns out those Pennsylvania police weren’t quite so rabidly overdoing it as it sounds. The first amber bulbs looked as though they’d been through a school bus or taxicab paint booth:

The coating was a high-temperature translucent paint that went on thinly and stayed on the bulb for awhile if you were very careful not to scratch it during installation. They worked well enough to pass muster with the various states’ type-approval authorities. But translucence is not transparence, and that made optical problems. If you wear eyeglasses, imagine how well you’d see with Scotch tape over the lenses. You’d still know light from dark and red from yellow from green, but details? Nope. Most turn signals of that time used fresnel lenses: a magnifying bullseye aligned with the bulb, with concentric rings around the bullseye—like the lenses in the first pic of this post. All these optics were designed to look at the bright line of the filament, and magnify and spread its light. Replace the bright, sharp, fine line by a diffuse big ball, and yeah, turn signal output was definitely going to suffer.

That technical detail, however, was not the bee in the bonnet of one Merrill J. Allen, O.D., Ph.D., an optometry professor at Indiana University. He had a big ol’ hate-on for amber front turn signals right from the start, based only on the reduction in intensity caused by the colour filtration involved, whether on the bulb or in the lens. The scientific thing would’ve been to set up and run some experiments, but instead he just summarily decided what conclusion he wanted to be true—white turn signals are better—then went trying to justify it with incessant blather and irrelevant answers to other questions. There was no substance to his campaign; it was nothing but his guesses and pet ideas about just one of numerous factors that determine the conspicuity and safety performance of something like a turn signal. It’s difficult to imagine being able to accumulate his degrees and get to his position without knowing he was ignoring and violating completely basic principles of scientific understanding, and yet he bleated and hollered, at his every opportunity, that everyone else and all the research was wrong. Much like saying It’s chilly out today, so there’s nothing such as global warming.

Any kind of colour filter is going to reduce the amount of light emitted by the bulb; that’s what filters do, and that was understood and accounted for from the start of the whole thing. The light output spec for the amber bulbs was (and still is) 25 per cent less than for a plain bulb. But such was the volume of Allen’s squawking that the Automobile Manufacturers’ Association felt compelled to respond defensively. Here’s what the NADA said about it in their February 1965 magazine:

That didn’t stop Allen. Here, take a look at his spittle-flecked insistence that he’s right. See how much crap he flings, desperately trying to make some of it stick (left column), and note the professionalism of the researchers in their rebuttal (right column; TLDR highlighted):

The illustrious Doctor Allen (O.D., Ph.D!) made a couple more contributions to the vehicle lighting literature, and most of them were of no import in the long run. Doctors Mortimer and Olson, on the other hand—the researchers Allen tried and failed to torpedo—both had long, productive careers in the field. Their research was and is respectable because it was scientifically sound; they thoughtfully designed and carefully carried out experiments to answer questions, then reported the results without any mention of whether they lined up with any personal preferences or pet guesses. That’s the right way to do it, and you can see them in action here in the work that made Allen’s head explode: in 1966 they methodically studied the conspicuity of turn signals at various distances from lit headlamps and shiny chrome using colourless bulbs; the painted amber ones, and the then-new transparent “Natural Amber” NA bulbs. Click the first page here for the whole paper as published in Traffic Safety, put out by the U.S. National Safety Council:

Alright, so it was well and truly settled: amber front turn signals really are better than white ones, especially when the whole optical line of sight is unclouded (see-thru amber bulbs with clear lenses, or clear bulbs with amber see-thru lenses). But there were more flies in the ointment. Prior to the colour change, many vehicles around the world had, on each side, a single bulb with one bright filament for the turn signal function and one dim filament for the parking light function. These reciprocally-incorporated park/turn lights were discontinued when most countries adopted amber front turn signals, because those countries stuck with white front position (“parking”) lights. The 1968 Geneva Convention on Road Traffic, in specifying amber for all turn signals and white for the front position lights, defined a modification to the colour convention: still white to the front and red to the rear, but now amber to the side. Turn signals, intended to advertise lateral movement, were placed in this side category rather than the front and rear categories.

If there had to be two colours instead of one, there also had to be two lights instead of one: amber turn signals and white position lights on the front of the car, each with a single-filament bulb providing only its one function. Often the white front position light was incorporated into the headlamp by dint of a small bulb protruding through a hole in the headlamp reflector a short distance away from the main headlight bulb. This kind of front position lamps are still with us; they’re called “city lights” by Euro-fans for reasons to be explained in another post one day. They were easily implemented in the composite headlamps used in Europe, but sealed beams are, erm, sealed—no way to make a hole in the reflector without ruining it.

So the British sealed beam industry figured out a workaround: they provided about a one-inch circle of unreflectorised area below the filaments. The reflector was made of pressed glass, so this meant a small see-thru window. A stamped metal cup was cemented to the back of the reflector, centred on the window, and a small bulb was socketed into that cup. That bulb’s white light shone through the circular window and bounced around inside the sealed beam, providing a white front position light. Here are Lucas sealed beams showing the window and the reflector cup:

If the American industry knew about this solution at all, it made them laugh or scream or both: Are you nuts? That’s going to add cost! Why, they’d have to change the wiring harness; the headlamp buckets; the sealed beams themselves…that’s a flat no! What are you, anyway; some kinda commie‽ (To be fair, there was one valid argument against this solution: removing reflector area reduces the amount of light produced by the headlamp—a bigger concern with smaller headlamps than with bigger ones.) As previously mentioned, the SAE standards called for “white to amber” parking lights, so when turn signals changed to amber in America, parking lights came along for the ride. Most vehicles still had the single two-filament park/turn light, just now in amber. That brought some new concerns. Take a look at this what an outfit called the Automobile Legal Association came up with as reported in Product Engineering on 23 December, 1963—amber parking lights look too much like red tail lights:

H’mmm. That’s an interesting question, and a bit of an unsettling one. I’ve looked, but I’m not aware of any methodical research into whether amber parking lights present this or any other significant hazard—I’m guessing probably not really, though they break the white-front/amber-side/red-rear convention—but Consumer Bulletin picked up and ran with this in their August 1964 issue:

This concern fizzled out; amber parking lights remained allowable and common in North America; allowed but not common in a few other countries, and banned in Europe and most other countries. In the long run, Europe’s rejection of amber parking lights wound up benefitting motorcyclists; about forty years after all this kerfuffle, the European regulations—by then applied in most of the world outside the North American regulatory island—were changed to allow (only) motorcycles to have amber front position lights. The idea was to give motorcycles better conspicuity as motorcycles in nighttime traffic. A fine idea, likely good for safety, but we can’t do it in North America because all vehicles are allowed to have white or amber parking lights, and motorcycles aren’t required to have any at all.

But wait! There’s more!

It seems even after all the states got onside and changed their statutes to permit amber where only white was allowed before, some of them backslid and refused inspection stickers to some cars with clear lenses and amber bulbs. The 1964 Studebakers started out using clear lenses and amber bulbs, then the factory changed back to the 1963 arrangement of clear bulbs with amber lenses to placate those states. Take a look at this Studebaker service bulletin from April 1964:

Now, something doesn’t quite sit square with me about this. Studebakers were far from the only 1963-’64 models with the clear lens/amber bulb arrangement. There was never an amber version of the 1963 Plymouth park/turn lens, for example; only clear ones, with those 1034A amber bulbs behind them. Chrysler never issued a service bulletin or amber lenses for those, and I’ve never heard or read stories of ’63 Plymouths flunking inspection on account of clear lenses, number one. Number two, recall that in those days before federal regulation, each and every lighting device had to be type-approved by each and every state. Those states had approved those Studebaker and Plymouth lights, clear lenses and all, otherwise the cars wouldn’t have been offerable for sale there. My best guess, given Studebaker’s tiny sales volumes, is that a small handful of owners got hassled by poorly-trained inspectors and complained to Studebaker, who misreacted as described in the bulletin rather than cordially inviting the states to perform certain specific anatomical impossibilities. [Update: see comment below by Rob, posted May 8, 2022, for another perspective on why Studebaker owners might’ve been singled out for harassment]

So that’s just about the whole story on how amber front turn signals came to America. Most of Europe changed to amber without any fuss in 1967-’68, but Italy did not; Italian national regulations carried right on specifying white front turn signals. But Italy had also been one of the first countries (if not the very first) to require side turn signals, likely due to that country’s heavy population of bicyclists sharing narrow roads with cars. Side turn signals had to be amber, but front ones in Italy had to be white. Some automakers chose to install separate amber side turn signal repeaters as would eventually become common throughout Europe and much of the rest of the world, but that was not the only acceptable option; if the front turn signals had sufficient lateral light distribution, they could also serve as the side indicators—but they still had to produce white light to the front and amber to the side.

Automakers and their lighting suppliers devised some clever solutions to do just that. Front turn signals with enough wraparound had transparent amber lacquer applied to the outboard extent of the lenses or an amber section of plastic moulded in, so one colourless bulb (or sometimes two of them) provided a white front turn signal and an amber side turn signal function. Let’s have a diaporama :

Mercedes W123 Italian-spec front turn signals (latter-day reproductions, I think)…


…as installed on the car (these are originals).


VW Typ 3 Italian-spec turn signal lenses…

…as installed on the car.


Mercedes R107 Italian-spec front turn signal lenses recto…


…and verso.


This is the only picture I’ve ever found of the exceedingly rare Italy-spec Volvo 164 front park-turn lights.


Porsche 911, Europe/rest-of-world. Inboard white front position lamp; outboard amber turn signal.


Porsche 911, US/Canada: inboard amber front position lamp, outboard amber turn signal.


Porsche 911, Italy: inboard white front position lamp; outboard white turn signal, amber wraparound for side turn signal


BMW 2002 front turn signals, front to back: US/Canada; Europe/rest-of-world, Italy.

BMW E9 Italian-spec front turn signal lens…


…as installed on the car.


An especially interesting case is that of the VW Beetle, which had not only a special white/amber lens for the front + side turn signal, but also an Italy-specific turn signal housing. It was similar to the chromed metal housing used elsewhere, but with a window in the outboard wall exposing a portion of the elsewhere-covered part of the lens, which was lacquered amber:

The Italian requirement for white front turn signals remained in force until 1977, when Italy adopted the amber front turn signal that had by then been common throughout the rest of Europe for most of a decade.

So, what lessons can we draw from this giant kerfuffle over what seems like a triviality?

• Some good lighting that probably improves traffic safety doesn’t make it beyond statutory borders, and sometimes falls victim to regulatory blind spots. The Italian windowed VW Beetle turn signal is obviously superior to the rest-of-world unwindowed item, and it could just as easily have been used with an all-amber lens. But a basic tenet of the European (later UN) vehicle regulatory system is that anything not explicitly permitted is prohibited, so the Italian turn signals couldn’t be installed elsewhere.

• It can be difficult to optimally and finally assign light colours even when there’s an overspanning colour standard such as white front/amber side/red rear. Turn signals, over the years, have migrated from being considered front (white) and rear (red) lights to being treated in most countries as lateral (amber) lights, and research as well as most of the world’s consensus supports the latter view—but at a philosophical level, both arguments are cogent; one can just as correctly argue either that front and rear turn signals are front and rear lights, or that turn signals are to advertise lateral motion and therefore count as side lights no matter where they are mounted.

• There is very little new under the sun (or moon); Japanese automakers, in the ’80s to early ’00s, tended to put white front position lamps at the front corners of the vehicle, outboard of the headlamps and wrapping round to the side. To meet the unique American-market requirement for front side marker lights, they often simply coloured amber the outboard portion of their rest-of-world front position lamp, in a close reprise of the old Italian technique. This Camry item uses a single clear bulb casting white light through the clear lens to the front; amber light through the amber lens to the side:

So, at long last, I hope that’s all clear (er, amber)!