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♫ music ♫

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If you’re among the folks who drive a car to get around,

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and you’re a good egg who uses turn signals like you should vote —

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early and often

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— you’ll probably have been in this situation;

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You’re sitting in a turning lane, with your signal on

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because again you’re a good egg,

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and despite all the projection of good vibes
you can muster,

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you just can’t get your turn signal to sync up with the car in front of you.

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Why?

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You’d think this wouldn’t be so difficult,

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after all it’s just a blinking light,

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but try as you might even if you appear to get it synced

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eventually one signal drifts away from the other.

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Turns out there’s a very simple explanation
for why you can’t get two indicators to flash in sync.

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It has to do with how turn signal circuits
function.

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Except, these days?

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Those circuits don’t work like they used
to,

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and, with the right car in front of you,

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you absolutely can sync yours up.

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There’s no trickery going on here.

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These are three different completely unmodified cars,

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all different model-years, made 4 years apart,

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but their indicators stay in lockstep
with one another.

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What’s going on here?

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Computers!

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But let’s step back in time and look at
how turn signal circuits used to work.

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Cars have needed blinky lights on them for
communicating your intent to those around you

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for many decades,

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long before the word "microcontroller" ever left an auto executive’s mouth.

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Although we experimented with goofy ideas
like trafficators

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or delightfully quaint displays like these,

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eventually we settled on flashing lights

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— the flashing helps to get your attention —

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placed at the corners of vehicles.

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Most of the world has decided you need to
have amber-colored lighting at all four corners for indicators,

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but for some reason this continent
thinks red is OK on the rear

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and even worse we’re just fine with combining the functions
of the stop lamp and the turn indicator into one lamp!

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It’s really not great for several reasons,

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but that’s an old video of mine.

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Now, as you may imagine,

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if turn signals haven’t fundamentally changed since the 1950’s,

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the circuit which makes them possible is probably pretty simple.

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And in fact it is!

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It would be really great if we had an old-fashioned
 turn signal circuit we could take a look at.

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Luckily...

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I have one

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right

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here!

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And yes, I know the headlights are facing backwards
if the steering wheel is facing you,

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but, look, this is just a demonstration.

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Deal with it.

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This is a steering wheel and (truncated) column
assembly out of a late ‘80s Honda.

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It was important that it be that old, 
and you’ll understand why by the end of this video.

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These are your stalks.

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Like corn, but plastic!

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In this car, these control wipers and all exterior lighting.

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To the left is the turn signal stalk and headlight switch.

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And to the right is the wiper stalk.

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These are all real, current-carrying switches.

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You can see on the connector for the headlight
switch some rather beefy pins,

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and that’s because all of the current for the headlights
and whatnot traveled through this thing.

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And being a 12V electrical system, even though
the headlights may only consume 120 watts or so,

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that’s 10 amps.

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Though, for safety’s sake, each headlight is usually on its own fused circuit.

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It's better to not lose both at the same time should there be a fault.

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The switch we’re interested in is this guy.

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I’ve always admired these for how many functions
they manage to make work on a single control.

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In this car, twist the end to engage the parking lights and headlights.

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Pull it towards you to flash the high-beams.

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Pull it until it clicks to engage the high-beams

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(though in many cars you actually push it away for the same).

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Or if it's old enough it could be a switch on the floor.

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And then push it down or pull it up to engage the turn signals.

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By the way, if you’ve never realized this 
(and I know people who haven’t)

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you push it in the direction that you will turn the wheel.

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So to signal left, you push it down because
the left side of the wheel moves down when you turn left.

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And if for some reason you have a Japanese
domestic market car like some sort of eccentric person

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(or I suppose, if you live in Japan)

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the stalk is on the other side so the direction you push it is reversed, 
but the idea remains the same.

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You shouldn’t have to think about which
direction to push the stalk,

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and if you were taught to memorize up is right and down is left,

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well I’m sorry. It’s deliberately quite intuitive.

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So anyway, the three smallest contacts are
for the turn signals.

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One is common, and the other two are for the
right side of the vehicle and the left side of the vehicle.

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Engaging the stalk simply bridges the common
pin to one of the other two,

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so if we build a circuit where 12V is present on the common pin,

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it will send 12V out on one of the other pins when we engage the turn signal.

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Then, all we need to do is send that 12V to
a couple of lamps and voila!

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Turn signals.

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See?

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Push down and we light up the left side.

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Push up and we light up the right.

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Job done!

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Except, eagle-eyed viewers will notice it’s not flashing.

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Ah, yes, that complication.

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So, how do we get the light to stop being so… steady

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and start gettin' all blinky?

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Why, with one of these things!

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This is a turn signal flasher.

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Some people call this a flasher relay which,

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ehh... sure but, uh, it's not a relay.

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It’s just a clever way to repeatedly interrupt
and reconnect a circuit.

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If I put this in series with the 12V supply for the lights

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take a look at what happens.

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That is a proper turn signal!

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It’s even making the noise and everything.

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[faint clicking]

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Yeah, this is what makes - or at least, made that clicking sound.

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Now if you’ve been watching this channel
for a while you’ll probably have guessed that where there’s a click,

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there’s a switch, and you’re right.

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But even better, making that switch do its
switching thing

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is our old pal the bimetallic strip!

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Yes, the same technology that toasts bread
to perfection,

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regulates your home’s temperature or even just tells you what it is,

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and makes your Christmas lights flash

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makes your turn signals flash.

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And if you’ve ever put a flasher bulb in
a set of Christmas lights,

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you’re probably well on your way to understanding why getting
your car to sync up with another one

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has historically been so hard.

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Look.

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This is a different flasher, but it’s the same exact model.

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That is a very different flash.

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Not only is it a different speed, but the
on and off time aren’t quite the same.

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Yet nothing else changed.

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Hmm...

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So what is in these things?

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If you pick them up you'll notice that they are very, very light.

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It feels like there’s almost nothing inside them at all.

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And indeed, there’s hardly anything in there at all.

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Shall we open one?

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Heh, no need, the Magic of Buying…

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Three of them has us taken care of already.

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Now this mechanism is a little confusing,

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mainly because of this paper insulator that’s pretty easy to miss.

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Right now, the two pins aren’t exactly bridged together.

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Measure the resistance across them and you
get about 37 ohms.

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At 12 volts that’ll pass about a third of an amp, or 4 watts.

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When you first turn on the signal, nothing happens.

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However, a complete circuit is actually made right here.

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Current is flowing through the filaments of the lamps themselves,

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in fact about a third of an amp,

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but this thing is preventing the lamps from actually
glowing because that’s just not enough power.

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It’s essentially behaving as a choke point in the circuit,

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being the point of highest resistance.

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That resistance is coming from this tiny little
wire which will get quite hot pretty quickly.

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And now the bimetallic effect comes in.

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The wire wraps around and around this strip of metal,

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and the 4 watts it’s dissipating quickly heats that up.

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Once it's hot enough, this piece will snap to the left,

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and these switch contacts are now closed.

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At this point, the resistance of the flasher is negligible,

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so current easily flows through it and lights the lamps.

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However, when those contacts are closed,

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well now the path of least resistance is around that little heater wire.

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No current will flow through it so long as
these two contacts touch, so what happens?

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Well, it stops being a heater, and the metal
strip cools down.

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So after a brief period of being closed and
lighting the lamps,

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the metal strip pulls the switch contacts apart.

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But of course now that heater’s back in
action, so just as quickly as it cooled,

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it’s hot again and the switch contacts are pulled
back together.

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And this will repeat endlessly, until ya shut of yer blinker.

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Pretty clever, huh?

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That’s how turn signal flashers worked for many, many years

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and it was perfectly effective.

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However, it was very inconsistent.

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If you pay close attention you can even tell
that the speed is drifting quite a bit.

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And that of course means… synchronization is impossible.

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Look, here’s all three flashers together.

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Despite being the same model of flasher,

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with the same lamps, and connected to the same battery,

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they quickly drift apart.

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Oh but it gets worse.

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Thermal flashers like these will also speed up and slow down depending on the voltage they receive.

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Look. I've swap this power supply for the battery,
and as I increase the voltage

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the flashing speeds up and also changes a little bit.

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Now, if you weren’t aware, once a car’s engine
is running and the alternator is producing voltage,

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the system voltage goes up to around 14 volts,

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and it can dip when there are loads on the system.

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So even if you have two flashers that miraculously
stay in sync with one another,

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if your car’s cooling fan, for example, comes on,

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well the resulting voltage drop is gonna quickly wreck that synchronization.

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But, there’s something we’re overlooking.

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Thermal flashers are pretty rare and as far
as I can tell have been for quite a while now.

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Notice how quiet this thing is.

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[it's very quiet]

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You barely hear a click at all when the light goes out.

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And also - the fact that there’s that substantial
delay between hitting the switch

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and it actually starting to flash - well that seems odd, doesn’t it?

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I can’t recall that happening in any car
I personally remember,

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and in fact in my 1991 Sillymobile that’s not how it works.

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Yes, to those that don’t already know,

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I bought this silly thing.

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Aging Wheels made a video about it if you
want to check it out.

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But anyway, its turn signals don’t change
speed depending on whether the engine is running or not,

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and the pace of the flash is very consistent.

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Plus the click is proper loud.

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[a proper loud clicking]

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I’m beginning to suspect this fella has
an electronic flasher of some sort.

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Hold that thought, we’ll get back to it.

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OK, so now, let’s look at some more modern flashers.

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Through the Magic of Buying…

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Four More of Them, two identical pairs,

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we can explore this further.

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First, here are two “long life” flashers.

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Because, you know, the longevity of the turn signal flasher
 is at the forefront of every driver’s mind.

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Anyway, these ones are way heavier - 
there’s definitely stuff in ‘em, for sure.

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And, that stuff?

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Well, it’s a relay coil and a capacitor ...

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and I think that’s it, actually.

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This style of circuit often contains a resistor
in there, too, but I don’t see one here.

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The theory of operation here is actually quite
similar to the thermal flasher,

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but rather than using a fluctuating temperature to open
and close a switch,

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we use a fluctuating voltage.

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Again, this is normally open.

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But not exactly.

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There’s a measurable resistance across it.

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A small amount of current has to pass through
this and thus the lamps in order for it to work,

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just like the thermal flasher.

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But here, when that initial current passes
through,

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it’s not heating a wire but instead traveling through the coil and charging the capacitor.

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As the capacitor initially charges, the voltage on the
coil rises

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which in turn means that the strength of the magnetic field it produces does, as well.

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Eventually it becomes strong enough to pull this little tab down,

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which closes the switch contact, therefore shorts the two pins together.

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That sends the full current out to the turn signal lamps.

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The stored charge in the capacitor is able
to hold the contacts closed for a brief period,

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but it quickly discharges through the coil winding itself.

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See I think in this application the coil is
the resistor, but I could be wrong.

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In any case, once the coil is too weak to hold on,

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the switch opens again and, wouldn’t ya know it,
 now the capacitor is starting to charge back up.

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Eventually the voltage is enough to pull the
switch closed,

233
00:13:44,253 --> 00:13:46,852
rinse and repeat.
[louder ticking]

234
00:13:46,852 --> 00:13:53,068
Here, the speed and timing of the flash will
be determined both by the value of the capacitor

235
00:13:53,068 --> 00:13:59,651
and the resistance in the coil winding 
(or the thus far elusive discharge resistor if there is one).

236
00:13:59,651 --> 00:14:03,056
So, could we get two of these to stay in sync?

237
00:14:03,369 --> 00:14:05,430
In theory, yes.

238
00:14:05,430 --> 00:14:07,800
In practice, no.

239
00:14:07,800 --> 00:14:12,391
This is an entirely analog circuit and the
thing about electronic components

240
00:14:12,391 --> 00:14:16,113
is they’re built to within tolerances.

241
00:14:16,113 --> 00:14:19,856
This may claim to be a 1600 microfarad capacitor,

242
00:14:19,856 --> 00:14:23,899
but it’s really that plus or minus maybe 10%.

243
00:14:23,899 --> 00:14:28,606
Similarly, the resistance of the coil isn’t
exactly the same from coil to coil,

244
00:14:28,606 --> 00:14:32,580
so you’re never going to have two of these behave exactly identically.

245
00:14:32,580 --> 00:14:35,501
And sure enough, these don’t.

246
00:14:35,501 --> 00:14:37,290
I mean, it’s not even close at all!

247
00:14:37,290 --> 00:14:40,585
In one of them the on time is longer than
the off time,

248
00:14:40,585 --> 00:14:44,460
and in any case the rate of flash is substantially different.

249
00:14:44,460 --> 00:14:46,400
Plus, as you may have already guessed,

250
00:14:46,400 --> 00:14:49,519
system voltage affects their speed, too.

251
00:14:49,519 --> 00:14:52,915
A higher voltage will cause the capacitor
to charge more quickly,

252
00:14:52,915 --> 00:14:56,580
so the amount of time it spends off gets shorter.

253
00:14:56,580 --> 00:14:59,555
It doesn’t have as much of an effect on the on time, though,

254
00:14:59,555 --> 00:15:03,836
as that’s mainly influenced by the time it takes the capacitor to discharge.

255
00:15:03,836 --> 00:15:07,827
Now, there’s a problem with the two flashers
we’ve looked at so far.

256
00:15:07,827 --> 00:15:14,001
They rely on being able to pass some current
through the filaments of the signal lamps themselves

257
00:15:14,001 --> 00:15:19,547
to either charge their capacitors
or heat their bimetallic strips.

258
00:15:20,457 --> 00:15:26,072
Because not all lights have filaments these
days, this has become a problem.

259
00:15:26,072 --> 00:15:33,410
So, you can now buy “electronic” or “LED-compatible”
flashers like this one.

260
00:15:33,410 --> 00:15:40,550
Here we have an added ground pin which allows
the flasher to function regardless of what else is on the circuit.

261
00:15:40,550 --> 00:15:45,570
And, dear viewer, I hope you’ll indulge
me as I make a public service announcement

262
00:15:45,570 --> 00:15:48,207
which may seem uncharastic for me.

263
00:15:48,634 --> 00:15:53,339
You should never ever ever ever put aftermarket LED
replacement bulbs in your car, ever.

264
00:15:53,339 --> 00:15:54,534
Don’t do that.

265
00:15:54,534 --> 00:15:55,521
It’s bad.

266
00:15:56,000 --> 00:15:57,000
Why?

267
00:15:57,149 --> 00:16:00,626
Well, here’s the thing about the signal
lighting on cars

268
00:16:00,626 --> 00:16:03,250
which many people seemingly aren’t aware of.

269
00:16:03,250 --> 00:16:08,300
I’m not just saying that, by the way, I’ve
had many discussions about this in my more...

270
00:16:08,300 --> 00:16:10,470
argumentative days.

271
00:16:10,470 --> 00:16:14,180
The honeycomb-looking lenses on your turn
signals and brake lights?

272
00:16:14,180 --> 00:16:15,660
They are functional!

273
00:16:15,660 --> 00:16:20,360
That is a real Fresnel lens, not just some pretty texturing.

274
00:16:20,360 --> 00:16:23,544
Your car’s signal lights are not simply diffuse,

275
00:16:23,544 --> 00:16:28,440
they are deliberately designed to magnify the filament of the lamp

276
00:16:28,440 --> 00:16:33,434
so that the signal appears brightest to those directly in front of or behind you.

277
00:16:33,434 --> 00:16:34,434
Look.

278
00:16:34,434 --> 00:16:41,180
I need to have this thing pointed pretty much
straight on at the camera for this to appear bright to you.

279
00:16:41,180 --> 00:16:46,830
If I move it off-axis even just a little bit,
the brightness is greatly diminished.

280
00:16:46,830 --> 00:16:50,348
To show this another way, look what happens
when I remove the bulb

281
00:16:50,348 --> 00:16:51,733
from this enclosure.

282
00:16:53,239 --> 00:16:56,308
This is the same bulb that you were just looking at,

283
00:16:56,308 --> 00:16:59,904
but without the benefit of the reflector and lens array,

284
00:16:59,904 --> 00:17:05,086
the filament is just a tiny speck and
it doesn’t appear nearly as bright to you.

285
00:17:06,812 --> 00:17:10,149
There is a narrow cone-of-maximum-visibility

286
00:17:10,149 --> 00:17:12,889
as you can see when I point this at a wall.

287
00:17:12,889 --> 00:17:18,426
These optical properties are what allow a
signal light to be visible even in direct sunlight,

288
00:17:18,426 --> 00:17:20,337
and they are important!

289
00:17:20,337 --> 00:17:21,956
And critically?

290
00:17:21,956 --> 00:17:27,711
The actual lamp assembly is designed around a specific bulb type.

291
00:17:27,711 --> 00:17:32,690
The filaments in a 1157 bulb like this are the same exact size

292
00:17:32,690 --> 00:17:36,102
and in the same exact place from bulb to bulb,

293
00:17:36,102 --> 00:17:43,192
precisely so that a replacement bulb will perform
 exactly as intended in the light fixture.

294
00:17:43,192 --> 00:17:45,920
Everything needs to line up optically.

295
00:17:45,920 --> 00:17:50,955
Remember, this looks bright because it’s
effectively magnifying the filament -

296
00:17:50,955 --> 00:17:53,029
so a tiny region of space

297
00:17:53,029 --> 00:17:56,769
- and making it appear larger to you in the camera.

298
00:17:56,769 --> 00:17:59,360
LED bulbs don’t have filaments,

299
00:17:59,360 --> 00:18:05,392
and while some better replacements out there attempt to mimic the placement of the filament in one way or another,

300
00:18:05,392 --> 00:18:08,607
it simply will not behave as intended.

301
00:18:08,607 --> 00:18:13,562
This is why the packaging for LED drop-ins
has to say “for off-road use only”

302
00:18:13,562 --> 00:18:19,426
or “check with your local laws” because using
these instantly voids the DOT compliance

303
00:18:19,426 --> 00:18:21,827
of your car’s light fixtures.

304
00:18:21,827 --> 00:18:27,835
It is not legal to modify the lighting in
your car in pretty much any way at all.

305
00:18:27,835 --> 00:18:35,206
It annoys me endlessly that stores like Walmart
sell these things because the function of your car’s signal lighting

306
00:18:35,206 --> 00:18:37,434
— especially the brake lights! —

307
00:18:37,434 --> 00:18:39,741
is a critical component to safety,

308
00:18:39,741 --> 00:18:42,772
and screwing around with this can be dangerous.

309
00:18:42,772 --> 00:18:47,760
Let’s give a real quick shout-out to those
folks who tinted their tail lights to look cool.

310
00:18:47,760 --> 00:18:53,499
Thanks for proving that common sense means
nothing when you can follow a trend and be stylish!

311
00:18:53,499 --> 00:18:55,333
Humanity sure is great, huh?

312
00:18:55,333 --> 00:19:00,912
Oh and you should know that these flashing
lights are straight-up illegal in most places.

313
00:19:00,912 --> 00:19:04,944
Only emergency vehicles are allowed to have
flashing red lights

314
00:19:04,944 --> 00:19:09,540
(outside of rear turn signals on this continent because… reasons).

315
00:19:09,540 --> 00:19:14,653
If for some reason you absolutely cannot resist
putting LEDs in your car,

316
00:19:14,653 --> 00:19:19,840
please check that they perform at least as well as your original lamps.

317
00:19:19,840 --> 00:19:27,142
Yes I know they illuminate instantly and I much prefer LED brake lights on cars designed for them for that reason,

318
00:19:27,142 --> 00:19:31,924
but if your new bulb isn’t as bright as the old one,

319
00:19:31,924 --> 00:19:33,894
that won’t matter much, will it?

320
00:19:33,894 --> 00:19:40,612
Compare the brightness between your original
equipment bulb and your replacement by only changing one first.

321
00:19:40,612 --> 00:19:45,538
Move around your car and check to make sure
the range of visibility is the same,

322
00:19:45,538 --> 00:19:51,594
and for brake lights make sure there is a substantial
difference between tail and stop intensities.

323
00:19:51,594 --> 00:19:55,646
Way too many of these replacements have hardly a difference at all.

324
00:19:55,646 --> 00:20:01,434
But the best way to ensure your lights work
like they should - as well as to keep them legal?

325
00:20:01,434 --> 00:20:04,340
Just use the bulbs they’re designed to use.

326
00:20:04,340 --> 00:20:08,950
If your car was built to use incandescent
lights, then use them.

327
00:20:08,950 --> 00:20:12,468
Thank you for listening to this public service
announcement.

328
00:20:12,468 --> 00:20:16,410
Alright so these final flashers, what’s inside them?

329
00:20:16,787 --> 00:20:19,510
Ah, now we have a circuit board!

330
00:20:19,510 --> 00:20:23,470
This looks sophisticated enough to be programmed
with a specific flashing ra-

331
00:20:23,847 --> 00:20:26,049
eh, no. We’ll just cut to the chase.

332
00:20:26,049 --> 00:20:30,740
Even in these flashers the speed is significantly
different between the two.

333
00:20:30,740 --> 00:20:33,110
But, these at least compensate for the voltage.

334
00:20:33,110 --> 00:20:37,413
No matter what I have this set to it flashes
at the same rate, although curiously

335
00:20:37,413 --> 00:20:41,675
as I adjust the voltage upward, it temporarily slows down.

336
00:20:41,675 --> 00:20:43,265
So that’s weird.

337
00:20:43,501 --> 00:20:48,538
Bottom line, these things have never been
made so precisely that any two of them

338
00:20:48,538 --> 00:20:53,980
will flash at the same exact rate, no matter what
their underlying technology is.

339
00:20:53,980 --> 00:20:59,230
It simply doesn’t make sense to use high-cost
components like a clock crystal and microcontroller

340
00:20:59,230 --> 00:21:04,160
when you only need to meet the target of 
“between 60 and 120 flashes per minute.”

341
00:21:05,133 --> 00:21:08,730
That’s what the law says regarding signal
flashing frequency, by the way.

342
00:21:08,730 --> 00:21:14,799
It’s not that precise, so these aren’t
and never have been built with precision.

343
00:21:14,799 --> 00:21:18,931
And frankly the law is probably that imprecise
because when that was written,

344
00:21:18,931 --> 00:21:21,413
this was the state-of-the-art.

345
00:21:21,413 --> 00:21:24,293
OK, but now I want to go back to the Figaro for a moment.

346
00:21:24,293 --> 00:21:30,620
Although this car is 30 years old, its turn
signal flasher behaves like the electronic unit we just looked at.

347
00:21:30,620 --> 00:21:34,256
There’s no delay at all between hitting
the switch and the lamps lighting,

348
00:21:34,256 --> 00:21:38,999
and the speed of the flashing is not only very regular
but also does not change

349
00:21:38,999 --> 00:21:42,250
when the car is running and the system voltage goes up.

350
00:21:42,878 --> 00:21:45,299
I wonder what this flasher is like...

351
00:21:45,299 --> 00:21:46,530
Well, here it is.

352
00:21:46,969 --> 00:21:51,498
Or, at least, a similar Nissan flasher from around the same era.

353
00:21:52,188 --> 00:21:54,910
Look, I’m going down this rabbit hole so you don’t have to.

354
00:21:54,910 --> 00:21:57,254
This thing certainly doesn’t feel empty,

355
00:21:57,254 --> 00:22:03,147
and indeed when we pull it apart there’s a whole dang circuit board in there

356
00:22:03,147 --> 00:22:06,256
with one of them integrated computer chips.

357
00:22:06,256 --> 00:22:10,359
This is much more phosisticated than the electronic
one we just looked at.

358
00:22:10,359 --> 00:22:12,062
How does it work?

359
00:22:12,062 --> 00:22:17,690
Well… I tried looking for a datasheet for this IC
but yeah that’s not really happening.

360
00:22:17,690 --> 00:22:21,758
A resonator might be in that chip somewhere
to provide a time signal,

361
00:22:21,758 --> 00:22:25,251
so let’s see if these signals, running on this flasher,

362
00:22:25,251 --> 00:22:28,037
will stay in sync with the Figaro.

363
00:22:28,037 --> 00:22:32,019
It’s extremely close, but not quite the same.

364
00:22:32,019 --> 00:22:36,300
I know that this isn’t the same exact part
number as the flasher in the Figaro,

365
00:22:36,300 --> 00:22:40,833
but it’s a genuine Nissan part from the same era and
the speed is so close

366
00:22:40,833 --> 00:22:44,974
that I can only assume they are both intended to flash at the same rate.

367
00:22:44,974 --> 00:22:47,411
But they still don’t exactly.

368
00:22:47,411 --> 00:22:52,887
They may appear to be in sync for a short
while, but eventually they drift apart.

369
00:22:52,887 --> 00:22:57,901
The main purpose of that IC is probably to enable hyperflashing.

370
00:22:57,901 --> 00:23:02,965
For decades now, it has been required that cars indicate a burnt out turn signal

371
00:23:02,965 --> 00:23:07,988
by changing the rate of flashing when that happens, usually upward.

372
00:23:07,988 --> 00:23:11,190
And indeed, if I take out a bulb from our rig here -

373
00:23:11,190 --> 00:23:15,792
now it flashes faster on one side than the other.

374
00:23:15,792 --> 00:23:20,790
This is the one advantage that a combined
stop-and-turn setup has -

375
00:23:20,790 --> 00:23:24,489
letting you know a brake light is out through hyperflashing
the turn signal -

376
00:23:24,489 --> 00:23:28,153
though that could easily be handled with one of these.

377
00:23:28,153 --> 00:23:30,767
But penny-pinchers gonna penny-pinch.

378
00:23:30,767 --> 00:23:36,729
That chip is probably there mainly to create
a current-sensing function for the hyperflash feature,

379
00:23:36,729 --> 00:23:41,881
and since they were going that far they might as well have 
made it handle the flashing more precisely

380
00:23:41,881 --> 00:23:44,781
using a resonator on the chip or something.

381
00:23:44,781 --> 00:23:49,848
Oh, also of note is that this flasher is also
used for the four-way hazard lights.

382
00:23:49,848 --> 00:23:55,038
You can see that on the label - hazard/warning is turn/signal X 2.

383
00:23:55,038 --> 00:24:00,189
A lot of older vehicles would actually have
a separate flasher for the hazards, fun fact.

384
00:24:00,189 --> 00:24:06,149
But this handles both, suggesting the flash
rate isn’t influenced directly by current going through it

385
00:24:06,149 --> 00:24:10,284
but instead changes only when it’s below a certain threshold.

386
00:24:10,284 --> 00:24:12,728
So, even though this is an electronic device,

387
00:24:12,728 --> 00:24:17,563
and it seems as though it has a very deliberately-programmed flash frequency,

388
00:24:17,563 --> 00:24:23,985
it’s just not precise enough to stay in perfect sync with another car
 - or at least its flasher -

389
00:24:23,985 --> 00:24:27,021
from the same manufacturer from the same time period.

390
00:24:27,021 --> 00:24:31,086
Why, then, do these three cars not drift apart?

391
00:24:31,086 --> 00:24:34,386
It really wasn’t hard at all for me to get
these to flash together.

392
00:24:34,386 --> 00:24:36,864
Look. It just took a bit of trial-and-error.

393
00:24:36,864 --> 00:24:43,853
Now in case you’re not hyper-aware of the
US car market to the point you can identify these vehicles with just this angled view,

394
00:24:43,853 --> 00:24:48,447
these are all General Motors products, Chevrolets to be specific.

395
00:24:48,447 --> 00:24:52,301
That’s a pretty significant commonality,
but you know what else they have in common?

396
00:24:52,301 --> 00:24:55,920
None of those cars have one of these!

397
00:24:55,920 --> 00:24:59,063
Have you ever noticed that starting around
10 or 15 years ago,

398
00:24:59,063 --> 00:25:02,572
the clicking sound of the turn signal changed?

399
00:25:02,572 --> 00:25:09,154
Pretty much every mainstream car made between
oh maybe 1980 and 2005 or so

400
00:25:09,154 --> 00:25:13,200
sounded exactly like this.
[classic, rhythmic tick-tock]

401
00:25:13,200 --> 00:25:14,860
Maybe it was a little louder.

402
00:25:14,860 --> 00:25:16,279
Maybe it seemed a tad muffled.

403
00:25:16,530 --> 00:25:22,052
But the tick-tock-tick-tock-tick-tock was
coming from one of these things

404
00:25:22,052 --> 00:25:24,490
tucked somewhere under the dashboard.

405
00:25:24,490 --> 00:25:28,531
You were hearing the actual switch contacts
opening and closing,

406
00:25:28,531 --> 00:25:32,912
and that served as the legally-required audio queue.

407
00:25:32,912 --> 00:25:34,532
Modern cars, though?

408
00:25:34,940 --> 00:25:37,150
They can sound like anything at all.

409
00:25:37,150 --> 00:25:40,260
Fords sound like somebody’s playing ping pong.

410
00:25:40,260 --> 00:25:43,181
They can sound like whatever the automaker
can imagine

411
00:25:43,181 --> 00:25:46,415
because that sound isn’t real.

412
00:25:46,415 --> 00:25:48,580
Look at this. This is my Chevy Volt.

413
00:25:48,580 --> 00:25:50,000
It’s not on.

414
00:25:50,000 --> 00:25:54,270
And now I’ll hit the hazard lights, which don’t
need the car to be running in order to work.

415
00:25:54,270 --> 00:25:55,490
They’re on.

416
00:25:55,490 --> 00:25:56,840
You can see them.

417
00:25:56,840 --> 00:25:58,280
But there’s no ticking sound!

418
00:25:58,280 --> 00:25:59,767
They’re just flashing!

419
00:26:00,238 --> 00:26:02,030
What is this madness?

420
00:26:02,030 --> 00:26:08,464
Well, for about a decade now, General Motors
products have been using the car’s stereo system

421
00:26:08,464 --> 00:26:11,215
to make all the noises a car has to make.

422
00:26:11,215 --> 00:26:14,759
So when the car is off and the stereo is powered down,

423
00:26:14,759 --> 00:26:18,271
it can’t make the ticking sound of the turn signal.

424
00:26:18,271 --> 00:26:20,858
It also can’t make two sounds at once -

425
00:26:20,858 --> 00:26:26,264
if I turn it on, the ticking sound doesn’t begin until the fasten seat belt chime stops.

426
00:26:26,264 --> 00:26:31,598
[bong, bong ends abruptly; then tick-tock begins]

427
00:26:31,598 --> 00:26:34,726
A Quirk only Doug could appreciate.

428
00:26:34,726 --> 00:26:40,538
This ticking sound is literally coming from
the driver’s side speaker in the footwell.

429
00:26:40,538 --> 00:26:42,151
Same with the chime.

430
00:26:42,151 --> 00:26:45,364
[loud chiming]

431
00:26:45,364 --> 00:26:49,222
As I said, it’s been like this for a long time in GM cars,

432
00:26:49,222 --> 00:26:54,320
and in fact they have to sell little noisemaker dongles 
that you plug into the radio’s wiring harness

433
00:26:54,320 --> 00:26:57,583
if you want to add an aftermarket stereo.

434
00:26:57,583 --> 00:27:00,331
On the one hand that’s kinda silly,

435
00:27:00,331 --> 00:27:06,083
but on the other their cars all come with 
a pretty sophisticated noisemaking device already

436
00:27:06,083 --> 00:27:10,841
so why not build the chimes and ticks and beeps and bongs into that?

437
00:27:10,841 --> 00:27:12,311
So they do.

438
00:27:12,311 --> 00:27:17,973
Now just because GM uses the stereo to make
the noises doesn’t mean every car company does.

439
00:27:17,973 --> 00:27:24,237
Others could certainly use a dedicated noise
maker thing, just like cars have been doing for the seat belt beeper for decades.

440
00:27:24,237 --> 00:27:31,272
But the point remains that in nearly all cases
these days the clicking sound isn’t real anymore.

441
00:27:31,272 --> 00:27:35,834
In fact, if you listen reaaaallly closely while
the car is off,

442
00:27:35,834 --> 00:27:43,082
you can hear the actual relay sending current to the turn signals
quietly ticking away under the hood.

443
00:27:43,082 --> 00:27:47,098
Well, I’m afraid I have to make a correction
because when I came out here to film the

444
00:27:47,098 --> 00:27:48,301
relays clicking…

445
00:27:48,301 --> 00:27:50,520
I can’t hear anything at all!

446
00:27:50,520 --> 00:27:54,772
I know the Equinox makes a faint noise but
apparently in the Volt…

447
00:27:54,772 --> 00:27:57,520
it’s probably transistors driving the turn signals.

448
00:27:57,520 --> 00:27:58,860
Whaddya know.

449
00:27:58,860 --> 00:28:03,252
See, the thing is, car companies have been
getting creative with using lighting

450
00:28:03,252 --> 00:28:05,980
to mean other things for a long time.

451
00:28:05,980 --> 00:28:11,740
GM cars use the turn signals as visual confirmation
of locking and unlocking with the remote.

452
00:28:11,740 --> 00:28:13,901
Lots of others do the same.

453
00:28:13,901 --> 00:28:18,960
Rather than create some sort of Frankenstein
circuit which can hijack the signal flasher,

454
00:28:18,960 --> 00:28:25,299
they just got rid of it and gave that task
over to some relays controlled by a body module.

455
00:28:25,299 --> 00:28:28,740
In other words a small computer in charge of stuff like that.

456
00:28:28,740 --> 00:28:30,280
This turn signal switch?

457
00:28:30,280 --> 00:28:33,910
It’s not handling any meaningful amount of current like this one.

458
00:28:34,192 --> 00:28:35,950
It’s just an input.

459
00:28:35,950 --> 00:28:39,097
It simply has to tell whatever module runs
the turns signals that

460
00:28:39,097 --> 00:28:43,120
“hey, I’m in the UP position” and then that module will say

461
00:28:43,120 --> 00:28:46,880
“Ah, time to flash the right side - hey you in the gauge cluster!

462
00:28:46,880 --> 00:28:48,960
Start animating that little blinker arrow.

463
00:28:48,960 --> 00:28:51,460
And hey, stereo, get clicking!

464
00:28:51,460 --> 00:28:56,009
While you two do that I’m gonna repeatedly apply
power to these two light bulbs.”

465
00:28:56,009 --> 00:28:58,798
And this particular car, infuriatingly,

466
00:28:58,798 --> 00:29:02,023
doesn’t do all that with perfect coordination.

467
00:29:02,023 --> 00:29:07,099
The animation, sound, and actual flashing
are all just a little out of sync.

468
00:29:07,099 --> 00:29:10,860
It’s great. 
Definitely not bothersome to the kind of person I am.

469
00:29:10,860 --> 00:29:13,601
Oh, and making this simply an input

470
00:29:13,601 --> 00:29:21,100
is what has enabled stuff like the tap-for-a-lane-change feature which some of you have intense feelings towards.

471
00:29:21,100 --> 00:29:25,080
To those of you on Twitter, I just want you
to know this video was in the works long before

472
00:29:25,080 --> 00:29:26,860
we had that particular discussion.

473
00:29:26,860 --> 00:29:29,128
I mean did you really think I could turn this around so f-

474
00:29:29,128 --> 00:29:34,830
Cars have been computerized to a degree that
I think very few people recognize.

475
00:29:34,830 --> 00:29:40,380
You know how you have a LAN, your local area
network, running over Ethernet in your home?

476
00:29:40,380 --> 00:29:42,828
Your car has a CAN bus.

477
00:29:42,828 --> 00:29:45,197
Literally car-area networ -

478
00:29:45,605 --> 00:29:49,026
OK I’ve been informed it’s actually controller area network.

479
00:29:49,026 --> 00:29:54,867
Anyway, there is a digital communications
network traveling on wires throughout your car

480
00:29:54,867 --> 00:29:57,545
which various modules communicate over.

481
00:29:57,545 --> 00:30:01,788
And the first car to use this standard was
produced the same year this thing was.

482
00:30:01,788 --> 00:30:03,611
1991.

483
00:30:03,611 --> 00:30:07,182
We started doing this because cars just keep
getting more complex

484
00:30:07,182 --> 00:30:10,277
and there’s no sign of that stopping any time soon.

485
00:30:10,277 --> 00:30:16,318
The CAN bus allows for controlling the various
whatevers in a car with much less wiring.

486
00:30:16,318 --> 00:30:18,999
Take power windows just as an example.

487
00:30:18,999 --> 00:30:24,323
Before the CAN bus, these switches were - again - 
literal current-carrying switches.

488
00:30:24,323 --> 00:30:28,153
That meant if you wanted the driver to have
control over all four windows,

489
00:30:28,153 --> 00:30:33,827
you’d need to route heavy-gauge wiring into the driver’s
door for every window.

490
00:30:33,827 --> 00:30:39,697
A CAN bus allows these buttons to simply send
a message that they’re being pressed to a body module

491
00:30:39,697 --> 00:30:45,254
which controls the window motors, and in fact you could do all the communicating for all of the switches

492
00:30:45,254 --> 00:30:47,886
with a single pair of wires if you wanted.

493
00:30:47,886 --> 00:30:51,780
You then also get the ability to integrate
modules together to do clever things

494
00:30:51,780 --> 00:30:56,969
such as roll all the windows down when you press
and hold unlock on the keyfob.

495
00:30:56,969 --> 00:31:01,516
That’s a neat party trick which GM has seemingly
haphazardly implemented.

496
00:31:01,516 --> 00:31:05,576
The Equinox and Bolt shown here can’t do this.

497
00:31:05,576 --> 00:31:08,581
We could do a whole video series on that sort of thing,

498
00:31:08,581 --> 00:31:10,074
and in fact I kind of want to,

499
00:31:10,074 --> 00:31:12,120
but here’s why it’s relevant.

500
00:31:12,120 --> 00:31:15,476
To make this network of things talk to each
other correctly,

501
00:31:15,476 --> 00:31:22,811
each thing needs its own precise clock - something to drive its internal processing circuitry at the appropriate speed.

502
00:31:22,811 --> 00:31:30,098
The signals on the network need really specific
timing and frequencies to be intelligible between nodes on the network,

503
00:31:30,098 --> 00:31:34,906
so unlike this circuit which may use a cheap resonator if it even has one,

504
00:31:34,906 --> 00:31:40,545
the body module in charge of flashing the turn signals, just like every other module on the CAN bus,

505
00:31:40,545 --> 00:31:45,674
will have a very precise clock operating at a very specific frequency.

506
00:31:45,674 --> 00:31:52,719
And so, if the manufacturer has decided that
their cars will flash the turn signals at 90 flashes per minute,

507
00:31:52,719 --> 00:31:56,855
it will be EXACTLY 90 flashes per minute.

508
00:31:56,855 --> 00:32:00,718
None of this “close-enough” that flashers of the past aspired to -

509
00:32:00,718 --> 00:32:01,864
exact.

510
00:32:01,864 --> 00:32:08,049
So, if you’re behind a car from the same
manufacturer as the one you’re in and they’re both relatively recent,

511
00:32:08,049 --> 00:32:11,138
you can probably get your turn signal synced with theirs.

512
00:32:11,138 --> 00:32:14,344
I haven’t tried it with anything other than
GM products, but

513
00:32:14,344 --> 00:32:18,182
I’ve synced mine to plenty of other Chevys and a Buick, too.

514
00:32:18,182 --> 00:32:23,401
For fun I’ve tried to see if BMW might use the same
flash frequency as GM

515
00:32:23,401 --> 00:32:27,574
but I’ve literally never had an opportunity to check for some reason.

516
00:32:27,574 --> 00:32:29,219
So - there’s the answer.

517
00:32:29,219 --> 00:32:33,807
It used to be basically impossible to synchronize
the turn signals of two different cars

518
00:32:33,807 --> 00:32:39,651
because turn signal flashers just weren’t precision
devices by any stretch of the imagination.

519
00:32:39,651 --> 00:32:44,682
But now it’s actually pretty easy - at least,
among cars of the same make.

520
00:32:44,682 --> 00:32:49,350
Give it a try next time you’re out and about
but, like, when it’s safe to do so.

521
00:32:49,350 --> 00:32:51,961
Don’t be foolish, drive safely.

522
00:32:51,961 --> 00:32:54,935
That means use your turn signals, also!

523
00:32:54,935 --> 00:32:56,756
Yeah, I’m talking to you.

524
00:32:56,756 --> 00:32:57,908
It’s not hard.

525
00:32:57,908 --> 00:32:59,644
Literally next to effortless.

526
00:32:59,644 --> 00:33:02,476
Make it a habit and you won’t even think about it.

527
00:33:02,476 --> 00:33:07,350
Well... unless your car has a really weird
and non-standard turn signal control

528
00:33:07,350 --> 00:33:10,610
because stalkless driving is a feature now?

529
00:33:10,610 --> 00:33:12,780
Before I go, here’s a fun fact.

530
00:33:12,780 --> 00:33:19,447
GM cars - or at least, some of them - have individual control over each turn signal position.

531
00:33:19,447 --> 00:33:24,517
When you use a scan tool to tell the car you’re
programming new tire pressure sensors to it,

532
00:33:24,517 --> 00:33:31,735
it lights up each individual turn signal on each corner of the
car to tell you which tire it’s looking to pair.

533
00:33:31,735 --> 00:33:33,365
It starts with the front left,

534
00:33:33,365 --> 00:33:40,226
keeping that light solidly lit until your pairing tool successfully prods that wheel to start talking to the car.

535
00:33:40,226 --> 00:33:42,921
Then it honks and lights up the front right,

536
00:33:42,921 --> 00:33:45,252
moving clockwise around the car.

537
00:33:45,252 --> 00:33:50,208
I’ve got winter tires and I’ve seen the
techs go through this rigmarole each seasonal swap.

538
00:33:50,208 --> 00:33:53,613
I was genuinely delighted by that bit of cleverness.

539
00:33:53,613 --> 00:33:55,259
Tickled me pink, it did.

540
00:33:55,259 --> 00:33:59,745
Oh, also, here’s a feature that GM seems
to have removed which is a shame.

541
00:33:59,745 --> 00:34:03,929
Deep in the menu settings of the Volt is a
setting called “Chime Volume.”

542
00:34:03,929 --> 00:34:07,820
You can actually toggle the volume of the
chime between two levels,

543
00:34:07,820 --> 00:34:13,804
but what it doesn’t tell you is that this also affects the loudness
of the turn signal clicker!

544
00:34:13,804 --> 00:34:19,529
This is genuinely really useful, as in lots
of cars I can’t hear the clicking at highway speeds.

545
00:34:19,529 --> 00:34:23,149
On the loud setting you definitely can in this car.

546
00:34:23,149 --> 00:34:27,834
Unfortunately, while the Bolt has even more
settings for the chime volume,

547
00:34:27,834 --> 00:34:29,036
that’s all it affects.

548
00:34:29,036 --> 00:34:30,036
Just the chime.

549
00:34:30,350 --> 00:34:31,068
Shame.

550
00:34:31,413 --> 00:34:36,712
Also, in case you think this is a fluke, here’s
the same three cars flashing together.

551
00:34:36,712 --> 00:34:38,510
And now we’ll speed this up.

552
00:34:38,918 --> 00:34:40,800
Here we find something interesting.

553
00:34:40,800 --> 00:34:47,240
The Equinox and Volt - that’s the black
and red cars - are 2013 and 2015 model years.

554
00:34:47,240 --> 00:34:51,833
They also have incredibly similar switchgear and infotainment systems.

555
00:34:51,833 --> 00:34:56,942
These two stay completely together for tens of minutes, but the Bolt?

556
00:34:56,942 --> 00:34:59,073
It does eventually drift apart.

557
00:34:59,230 --> 00:35:01,825
It takes a while, so it’s extremely close,

558
00:35:01,825 --> 00:35:06,815
but this makes me think the Volt and Equinox probably have identical body modules,

559
00:35:06,815 --> 00:35:09,154
and the Bolt’s has been revised.

560
00:35:09,154 --> 00:35:15,479
The Bolt also has some radically different
user-interfaces compared to the other two which reinforces this idea.

561
00:35:15,479 --> 00:35:18,914
Plus it actually has amber rear turn signals,

562
00:35:18,914 --> 00:35:21,245
amazing!

563
00:35:22,186 --> 00:35:24,860
♫ indicatively smooth jazz ♫

564
00:35:25,990 --> 00:35:28,880
You can’t get it s… uh, no. That’s incorrect.

565
00:35:29,288 --> 00:35:32,877
[engine noise]

566
00:35:35,544 --> 00:35:39,754
But let’s step back in time and look at how turn signal circuits used to fwork.

567
00:35:39,754 --> 00:35:40,505
Fwork.

568
00:35:40,505 --> 00:35:44,344
Cars have needed blinky lights on the 
[a series of very silly noises]

569
00:35:44,344 --> 00:35:46,264
….and then push it down.

570
00:35:46,264 --> 00:35:47,404
Oh! It was engaged.

571
00:35:47,404 --> 00:35:48,404
Great.

572
00:35:48,935 --> 00:35:52,594
While I’m out here, that is the range of maximum visibility

573
00:35:52,594 --> 00:35:54,372
for the Volt’s brake lights.

574
00:35:54,372 --> 00:35:57,759
You can see it is very much a directed beam.

575
00:35:57,759 --> 00:36:03,085
It will send 12V out on one of the other pins
when we engage the circle.

576
00:36:03,085 --> 00:36:03,911
Signal.

577
00:36:03,911 --> 00:36:09,448
Put this in series with the 12V supply and
watch what happens.

578
00:36:10,766 --> 00:36:12,334
That was way too sloppy.

579
00:36:12,334 --> 00:36:16,948
Now if you’ve been watching this channel
for a while you’ll proba… Oh noooo!

580
00:36:19,834 --> 00:36:23,185
See, I should have definitely done something
more robust than this.

581
00:36:25,632 --> 00:36:29,042
It’s ‘cause you’ve been coiled up a
whole bunch of times.

582
00:36:29,042 --> 00:36:29,713
No.

583
00:36:31,847 --> 00:36:34,632
[sudden acceleration rearward]

584
00:36:35,981 --> 00:36:39,133
Current flows through the fff eh buh

585
00:36:39,133 --> 00:36:43,229
In any case, once the switch contacts open again…

586
00:36:44,861 --> 00:36:47,029
I lost my s… track.

587
00:36:47,029 --> 00:36:48,055
I lost where I was.

588
00:36:48,055 --> 00:36:51,185
Eventually the voltage is enough to pull the
switch closed,

589
00:36:51,185 --> 00:36:53,558
rinse and repeat.

590
00:36:55,127 --> 00:36:56,639
This is not connected.

591
00:36:56,639 --> 00:36:58,340
Great job, guys!

592
00:37:00,787 --> 00:37:03,626
Well, wasn't this video illuminating?

593
00:37:03,626 --> 00:37:06,603
Then again I suppose it wasn't for an equal amount of time.

594
00:37:06,603 --> 00:37:10,065
Kept going back and forth between enlightened and dim, huh?

595
00:37:10,065 --> 00:37:13,169
Man, is my material getting repetitive? Hope not.

596
00:37:13,169 --> 00:37:15,140
USE YOUR FORKING TURN SIGNALS