[0:26]Hi and welcome to Car Corner. My name is Richard Saxton. I'm the coordinator of the automotive programs here at the Community College of Philadelphia. In today's episode, Dan Reed is going to brighten your day with his discussion on headlights. If you have any questions about the programs here at the college, please check us out at the website. Okay, now it's time to get it in gear. Hi, I'm Dan Reed with the Community College of Philadelphia. Welcome to Car Corner. Today, we're going to be talking about automotive lighting systems. Now lighting systems are one of those things that has gone through many, many different generations as cars have evolved. Believe it or not, the first automobiles that were made had absolutely no lights on them whatsoever. So, not only could you not see where you were going at night, but also the people behind you and around you had no idea what your intentions were as you drove. This led quickly as cars became popular to the advent of having to have some type of warning device on the vehicle to at least allow people to know what you were doing while you were driving. And the earliest warning device was actually a rule proposed to have a flagman waving an orange flag in front of you as you drove your car down the street. Now this was not done necessarily to warn people, but to actually warn horses that your motorized carriage was coming down the street. This quickly fell out of favor because obviously the flagman could only walk so fast, and this was fine while cars could only go three miles an hour, but obviously they started to go faster pretty quickly. And one of the first lights that were invented were the stop lights and the head lamps on the car. Really, they were just a marker light to indicate that your car was an object in the road. And it didn't change color or intensity as you drove, it was just a light, and you actually had to get out and manually light the flame to light a gas powered lantern on your car. So, when we came to the advent of electric lighting, that was huge. That was a gigantic leap forward, the idea that you could just push a button and then you had electric light on your car. And it was such a desirable thing that it quickly evolved from an optional accessory on cars to a a necessary item, and since then, cars have been sold with electric lighting since then. So, first, let's talk briefly exactly how a basic light bulb works. Now, this is what's known as an incandescent bulb, and this is a fantastic drawing that I've made of how a basic light bulb works.
[3:05]And uh we can give Thomas Edison most of the credit for this, although there were some other uh inventors at the time working on an incandescent sealed light bulb. So, the light bulb uh basically has two legs. We have, we're going to send our electrical current through it. So there's a power and a ground, and the neat thing about light bulbs is they're not particularly, they don't care which direction they go. This thing that goes across here, this curly-shaped thing that looks like a spring, is called the filament. And the filament is made out of a specific metal that doesn't burn, but it glows, and it glows with a certain amount of intensity. Around the entire bulb is a glass globe. Now, the glass globe is important because what they found very quickly was that when they applied the electric current to this filament, and there was no glass globe, the oxygen in our atmosphere actually caused the filament to burn too quickly.
[4:00]And the bulb worked, but it worked for just maybe a couple seconds, and then that filament oxidized, it burned, and when it melted, it broke the electrical contact, and then at that point, the light bulb burned out. So, one of the other big struggles as well as the material that the filament was made out of, was how to figure out to make this sealed envelope, which we found that if we sucked all of the air out of it, made it a vacuum, um, it kept the filament from oxidizing, and it kept the filament from burning, and the bulb would last for a certain amount of time. As time progressed, engineers and scientists figured out by changing the gas inside the bulb or the material of the filament, what we found is that we could increase the brightness of the bulb, make it whiter light, rather than a yellow light. And we can increase the uh longevity of the bulb, we could have the bulb last for much longer time. So, that's when you hear things like a halogen light bulb, it means that instead of a vacuum, the bulb is filled with a halogen gas. And then sometimes we might have a tungsten carbide filament or something like that, and that means that the actual filament is made of a certain material. So we have all kinds of different lighting, sodium vapor lighting for basketball courts at night and things like that for stadiums, and um really, that's the basic lay down of of how a basic electric incandescent lamp works. If we look at a light bulb, um I'm going to put this one over here, um we can see that there are a set of filaments. And when you have the light bulbs and they're good, you can actually see that filament, you can see that curly-cue design on the inside of the filament. And then the bulb with the black top that I have next to it, that's a damaged bulb. You can see the two arms are up, but there's no filament across it. And in fact, when a bulb actually burns out, what happens is is that filament actually completely disintegrates, it melts. That can happen from a couple different things, it can happen from age, but typically the problem with incandescent light bulbs is that they suffer from issues of vibration. So vibration, shocking the bulb, literally dropping it, being very rough in the way that you handle it and smacking it against things is really what often how light bulbs get broken. And if you've ever broken a light bulb in your house, maybe a floor lamp or something, if it gets knocked over, usually the lamp gets very bright, and then it stops working. And then at that point, some people actually take the bulb and they shake it and they try to listen to see if they can hear the filament shaking around the inside. If they hear the filament shaking, they know the bulb is defective, and uh at that point they would change the bulb. So, now that we have a good idea of how light bulbs work, let's take a look at some of the different styles of lights that we have and uh how they fit into our automotive lighting landscape. When you really stop and think about it, it's not uncommon for a car to have possibly up to maybe 30 different light bulbs on it when you add them all up. The fact is is we take a lot of the lights for granted. You have the light in the ash trays, the lights in in the dashboard that actually illuminate the instrument cluster at night. And all those bulbs are not the same. While they may work in similar methods, like I just talked about how an incandescent bulb works, the fact is is those bulbs have different types of fittings and brightness values and wattages, which is the amount of power that the light actually consumes, which roughly translates translates into the amount of power that the light can put out. So, in terms of of selecting a different type of a bulb for your car, this is a chart, which I printed out off the internet. And I just, I just happened to look it up for a uh for a specific vehicle, a 2008 Buick Enclave. And um what you need to know is when you go and you have to replace a light bulb for a car, if it's a turn signal light or a tail light or something like that, you actually have to know uh the the number of the bulb. In other words, what type of light bulb is it? And each bulb has a specific number, and they're fairly standardized. So if you buy a light bulb from General Electric versus Osram versus Sylvania, uh versus another company, the the lighting numbers are standard. So a lot of times in the automotive industry, we'll call a bulb an 1157 or a a P21W or something like that, and that's automatically, it's the same bulb across the board from manufacturer. So, when you do have to replace a bulb, make sure that you get the exact bulb specifically for that product. Don't ever just look at the light bulb in the package and go, that looks like the right bulb, it might fit. The problem is is it might be the wrong intensity, and I have actually seen lots of cars with things like melted tail lights where they put light bulbs that were the wrong wattage in there. They got too hot for the housing, and it actually caused the plastic of the housing to melt and distort, in which case it goes from a five dollar headlight to possibly a two hundred dollar tail light assembly, much more expensive. So you don't want to make that mistake. So please make sure that you always look up the lighting chart for your vehicle. Most parts stores have a booklet, a lot of them have a computer system now where you go in and you punch in the numbers to look at exactly what type of light bulb you have and you need for your car. Give you an example of that, um these two light bulbs if you were to just glance at them, um they're almost the same exact bulb. In fact, if we flip them upside down like this, you can see that they actually have the same type of bases, um so they would fit in the same socket. But the fact is is they're two different numbers, uh one is a P21 bulb, the other one's 1157, uh they're not the same bulb. You can actually screw up again the housing and the lighting sockets, you can melt them and damage them by interchanging the bulbs. So, you just can't go by the the shape and the look of the bulb, you have to make sure that you get the right one for your car. So, starting in the mid-1980s, a lot of automotive manufacturers started to put halogen headlamps in their cars. And this was a great safety improvement over the older, what we called sealed beam non-halogen headlamps that kind of had a yellowy hue to them. The whiter light made the visual distance increase at night, and the light bulbs themselves actually lasted longer. There was a problem though with the halogen bulbs, and that is is that they run significantly hotter in their housings. And they actually run so hot that when you take them out of the package, you have to be very careful. You have to actually cut the packaging apart um at the sides. And when you remove the bulbs, do your best not to actually handle the actual filament glass housing itself with your fingers.
[10:52]You can handle the other parts of the bulb just fine. The problem is is that the actual oils from your fingers will create a hot spot on the light bulb. What that'll do is that'll actually run the risk of shortening the life of the bulb and having the bulb fail sooner than it would. So a lot of manufacturers recommend that if you have to handle the bulb in any type of way, you either wear a fresh pair of disposable um nitrile gloves or vinyl gloves. And or use a piece of tissue paper to actually absorb the oil from your fingers on the bulb, and if you happen to touch the bulb, you should use a sterile alcohol wipe to actually wipe off the surface of the bulb before you fully insert it in the car. This can be a little difficult in some cars, and I have a lot of headlight housings here next to me, and I'll show you them in a couple minutes. And the fact is, sometimes manufacturers maybe might not make it so easy to change the headlight, and what they actually want you to do is come back to the dealer. And some manufacturers do that because the lighting systems are so complicated, the bulbs are so expensive, they almost just don't even allow consumers to change the bulbs themselves because they had such a high failure rate because consumers weren't careful enough about keeping the oil off of the off of the bulb surface. I sort of follow that rule almost with any type of bulb. Really the heat from the oil from your fingers, make sure your fingers are clean and all that kind of good stuff, uh before you handle the light bulb. Bulbs get very, very hot when they're in their housings. All right. So, in terms of uh other types of light bulbs, we have uh different types of bases on the bulbs. And this is what's known if we see that we have a couple dots here, a couple mount points for the bulb, this is what's known as a dual filament bulb.
[12:42]And the dual filament bulb versus a single filament bulb, oops, I'll get that in a minute. Now, the dual filament bulbs are generally used in tail lights and turn signal assemblies, and what we'll do with those is we'll use one of the filaments as the brake light and or the turn signal, and then the other bulb is used as a running light or just a tail light bulb that comes on when your headlights are on. Um so again, you have to make sure that you have the right bulb for the right housing. The other thing is is that the housings that the bulbs actually fit in are designed to accept the small points on the bulb themselves. And you can put them in, and when you put it in, it's kind of a twist and turn lock mechanism to actually put the bulb in. And yes, I'm touching the bulb with my fingers, which I said you probably shouldn't do, but we'll ignore that for now. It's okay. Um so, when you do that, make sure you use tissue paper. Anyway, make sure that the bulb is fully seated and uh turned and locked when you put it in. You'll find that what I've seen with happens with some people is they'll actually try to jam and fit us another bulb in here, and they may be sort of successful in jamming it in there and getting part of it to work. But the fact is is that these these offset tips are designed to only let the bulb lock and turn in one direction. Um other manufacturers use what's known as a wedge based bulb, and that's a wedge base right there, that black piece with the two uh two wires on it. What's nice about the wedge based bulbs is they can actually go in either direction, and uh it's harder for consumers to mess these up. So this is what a lot of um manufacturers have gone to. The other thing that can happen with light bulbs is that when they age and fail, um we can see that the bulb may actually turn cloudy. Now, this cloudiness is on the inside of the bulb, it's not on the outside of the bulb, and uh what we'll try to do is we'll have this bulb fail in a couple minutes here. It's on its way out, and I'm going to see if I can finish it off and maybe we can capture it on camera. But if you happen to see that a bulb is getting getting kind of smoky, it sort of has this uh smoke on the inside of it. What that means is that that protective envelope, that vacuum has been broken. So, somewhere air is getting inside that bulb, and it's going to cause it to fail and burn out. So if you happen to inspect your tail lights, let's say you're replacing a tail light, and you see that one of them is cloudy and it hasn't failed yet, go ahead and replace it while you're in there because the fact is that bulb has a very short time to live until the other one fails. The other thing that most manufacturers recommend, and I'll just bring this back here, is that you generally replace bulbs in pairs. Don't bother replacing one bulb at a time. Bulbs have a limited amount of hours that they tend to run, and most manufacturers will sell you a package of two bulbs. You say, well I only need one. Well, the idea is that if one bulb has failed, the other bulb is not far behind it. So you might as well and just replace them both at the same time. It might seem like, well, that's twice as much work, it's twice as much money. But the fact is is most manufacturers actually recommend that you replace bulbs in pairs, just as we would replace brake pads in pairs or shock absorbers in pairs or tires in pairs or anything else on the car just so we get even left and right. And again, if I replace the left one and I replace the right one at the same time, I'll have a good amount of time before that one fails again. All right. So, let's take a look at how lighting circuits are actually put together in a car. So what I have here is I have some sample lighting boards, and we use these for training when we teach basic electrical here at the college. And uh what these are is these are these uh wedge based filaments, and this is this is a sample housing. So this would this would actually snap into a tail light or a turn signal or something, and I'll show you that in a couple minutes. But generally, when we have this, I have a 12-volt power supply. I'm going to plug this in, and when I turn it on, this this top light here is going to light up, and it's going to be, it's going to be fairly bright, it's going to be pretty intense. That would probably be the equivalent of maybe a a brake light on a car. So that's fairly bright. You think about how bright a brake light is at night. You know, you can see it from, you know, maybe up to a at least a quarter mile away. You know, if the weather's bad, that that range tends to decrease. But if we take this bulb out, and I put in this this damaged bulb, we'll see what happens as the bulb fails. Did you see that little teeny tiny pop? That was it. That was the bulb failing. That's a, that's all I got there. Sometimes if I smack the bulb or bounce it around a little bit, I can get it to come back for a split second. There we go. And what's actually happening at that point is when I when I shake the bulb, I'm actually vibrating that filament back together, and it makes electrical contact for just a split second and then it fails again. So, that didn't last very long. So let's put the good bulb back in there. We'll get rid of this guy because it's no good anymore. And uh if I just had one brake light in a car, that that could be my brake light circuit, it would go on and off. But in reality, when we have a tail light circuit for our car, you see some cars, they have multiple tail lights, they'll have three different segments that light up when you turn on the uh the vehicle. And the common way that we tend to wire electrical circuits in a car is what's known as a parallel circuit. Now, the other type of circuit that we have is a series circuit, and I'll I'll demo the series circuit first. In series circuits have a really bad fault. Um the fault with the series circuit is that the electrical current has to travel, it only has one path, which means it has to travel through each bulb, and uh the bulbs consequently get dim as they travel as the current travels through it. And then the other thing that happens is is that if one bulb burns out, the whole entire segment goes out, which makes finding the failed bulb difficult. So what I'll do is I'll I'm going to first demo this as a as a series circuit, and I'll put these bulbs together in series. And what I'm going to do is I have my power coming in the top here, coming out the bottom there. And I'm going to chain these together using my lighting board. And when I put this on, you're going to notice that suddenly the bulbs are much dimmer than they were before. Now, that's the same bulb, I haven't touched it, so it's not a television trick or anything like that. The fact is is now the voltage and current that that bulb was using is now being basically sucked up by these two other bulbs. And if I do something like take uh one bulb out, they're all going to go out. So, if I take my failed bulb and plug it back in, I suddenly don't know, well I can tell visually which one's failed. But if I didn't have that smoke color on the inside, I'd have to basically take these bulbs out and test them. And the joke is is that's what old Christmas lights were wired. They were wired in series, and when one bulb went out, they all went out, and then you had to go through and manually check every bulb on the string, and it was a frustrating thing, and nobody had any fun. If I remove one bulb and I shorten my circuit, and I take the power, and I get rid of one bulb, suddenly the other two bulbs are now brighter because there's more current and voltage available for the two bulbs.
