LED Lighting Conversion

For All 1983-88 Cougars / Thunderbirds

Page Revised: 10 March 2020


Article by
Eric Dess

As much as you may otherwise believe, I'm just an average schlub like you. I have a regular job with regular pay, most of the time I have weekends off, and if there's any spare time during the week I try to get into the garage and work on the cars. And when you have more than one car that you're trying to keep roadworthy, of course, that gets really tricky...and expensive. But that's how I roll.

So I set off in the winter of 2018 with the hopes that I could actually accomplish something great on at least one of the cars. The goal: convert an entire car over to modern LED lighting and make it look as stock as possible. Every single bulb. As it turns out, not only was the mission accomplished but I was able to convert BOTH cars in the same timeframe. It's not often you can say that, right?



As we all know, our cars were created in the golden age of the incandescent 12v automotive bulb. They were dutifully used for many decades without much of a real improvement, save for maybe halogens. They gave off a yellowish light, they burned out after some time, and they generated heat. Those were all givens. But probably the most important, yet least thought-about, element of the incandescent bulb is that it gave off a consistent light pattern from all angles. You and I never really gave it a second thought, but all of our light housings and surrounding reflector areas were designed around this basic characteristic.

So when you start messing around with other types of bulbs such as LEDs, you begin to discover rather quickly that not all bulbs are created equal. And not all bulbs will mimic that omnidirectional light pattern (I've got bags full of unusable LED bulbs to attest to that).

Therefore my goal—and yours—is to find a bulb that mimics the stock bulb but in an LED pattern, and is also dimmable when needed.

Also, I must say that money was no object in my case. Whatever it took to get the job done, I was willing to pay for it. Just like any other trial-and-error automotive experiment, that means I have a few hundred US dollars' worth of bulbs I'll never use. So be it. I took one for the team so you don't have to.


I found that converting the smaller bulbs is the easiest. Why? Well, LED bulbs that aren't pulling a lot of power will generally not need an inline resistor. They're just literally plug and play.

The most common bulb on our cars is the 194 (or 168, similarly) so that's where I started. And the first place to get that new bulb would be the front side marker on my '84. I'd know how well a bulb worked in that location because it would easily show uneven lighting. Plus, I could look at the car from the front and see both lights...if something was off a bit, I'd surely know it.

So off to eBay I went. There are lots and lots of different types, light ranges, and configurations out there. I quickly learned that the clustered, unidirectional bulbs aren't worth squat for our cars. They make a single bright spot and that's it. Next, I tried a round, domed bulb that looks similar to the incandescent bulb it's replacing. Close, but no cigar...the light was still going in more or less one direction. At least they were inexpensive at under US $1 each.

At this point I was so disappointed with the early test bulbs that I decided to just stop looking for the time being. Multiple eBay and Amazon searches weren't yielding any promising leads, and more of the same old bulbs that I'd just purchased were the only options, it seemed.

Then one day I was in a US national parts chain store and saw some name-brand LEDs hanging from the shelves. They looked interesting but I wasn't sure. There was a tester display for them that seemed to work impressively well. However, I was giving a hard stare at the ~US $9 price tag. If the bulb worked, it was not going to be cheap to upgrade the whole car. But I was in this all the way, no turning back now.

The younger salesperson working at the store told me he used these same bulbs on his truck. We went outside and he showed me the bulbs in action for his license plate lamps. Even in the late afternoon sunlight, they seemed pretty strong and bright. So I bought one to try out.

When I got home, I was shocked at the evenness of the light. THIS is what I had been searching for!

LED Bulbs

The winner: Sylvania/Philips. They currently have two different product lines and I honestly can't tell you what's different about them. All I know is, the more basic bulb in the white packaging is more common in whichever stores you frequent. So that's what I went with. These are the 6000K bulbs, by the way, also known as cool white.

It was at this point that some of the information I'd read about LED bulbs turned out to be true. If you're putting an LED bulb into a colored housing, the bulb should also be that color. So in an amber housing you'd want an amber bulb, red bulb in a red housing, and white anywhere else. This ended up being true for almost every situation. Otherwise the colors will be off, and not in a good way. (Purple taillights tend to attract unwanted law enforcement attention, if you know what I'm sayin').

LED Bulbs

Left to right: stock bulb, no, no, OH yes.

Also, it is true that LEDs tend to work only one way in the socket. If you install one and try the light, and it doesn't work, flip the bulb around the other way and it should. That's because it is a diode, after all. That makes it VERY important that you try all the new bulbs out before you start reassembling.

LED Bulbs

Later on I swapped out the white LED for the amber version in the front housing, and it is definitely better. It's very hard to tell that there's an LED bulb in there, almost impossible in fact. That made me very happy, as it foreshadowed the rest of the bulb replacement process.

LED Bulbs

At this point, the front side markers, the rear taillight markers, and the license plate bulbs were all replaced. That was as far as I could go on the outside with 194 bulbs.

Total so far: ~US $60.


One of the most annoying issues with the 1983-84 dash is the lack of good lighting at night. It's never been that good, to be honest, and over time the bulbs will start fading and dust will collect inside the cluster housing. This is one area where we all can use some help. So into the dashboard I tore.

For the 1983-84 cluster there are only 4 main 194 illumination bulbs. After swapping them out, I made the garage dark and hit the headlamp switch...what a HUGE difference in lighting quality. Best of all: they are dimmable! Now you're not going to get the same kind of dimming as incandescent here. It will go from super bright down to bright-ish, but not dim like before. Just so you're aware. But for my tastes, these were perfect as I always had the dash lighting cranked up anyway.

LED Bulbs

Upgraded dash lighting makes a world of difference.

Full disclosure: to save a little money I did not change out the warning lamp bulbs nor the turn signal indicator bulbs. Those will get replaced with LEDs when and if needed.

LED Bulbs

Eventually I also did swap out the clock bulb, the heater panel bulb (fun!), and even the bulb inside the lighter. What, you didn't know there was a bulb in there?

Next, I tackled the console with the ashtray bulb. This marked the end of the interior 194 bulbs...the rest would be different types that I hadn't found quite yet.

Total so far: ~US $140. (Ouch.)


So far, the most straightforward bulbs had been replaced and I was about a third of the way done. It felt good to accomplish this but I knew there was a lot more work ahead, and also some more research needed.

I wanted to work on the exterior lighting once more, and not knowing if the Sylvania/Philips bulbs were going to work, I decided to try some cheaper omnidirectional white 1156 LED bulbs that I found on eBay. Those are used for the backup lamps, and the trunk and hood lamps. They did not disappoint: lighting was even and very bright. Another few off the list! (In hindsight, the Sylvania/Philips bulbs would also be just fine in these locations).

So out back, all that was left was the brake/turn signal bulbs, and in front, the turn signal/marker bulbs and headlamps. I'd get to those later.

LED Bulbs

Back inside the car, I went on to replace the courtesy lights with the same 1156-style bulbs.

LED Bulbs

Then it was time to tackle the dome light. Did you know that there were two different styles of map dome lights in our cars? It depended on the model year, but the earlier cars had the older, fuse-style bulb while later ones had the plug-in style base. For my car, the 1156-style LED bulbs worked awesome in the map lights but I didn't find the correct fuse-style LED bulb for the dome light itself at the parts store. In the end, I bought 4 different ones off eBay and used the brightest one. Can't tell you where it was from. I don't know if Sylvania/Philips has an equivalent. But I can tell you that WOW what a difference in interior lighting now. When the door is opened, there is real, bright, usable light. It's probably enhanced a bit by the blue interior color too, but it's still quite impressive.

The console bulb was a little tricky, as Sylvania/Philips doesn't offer that size. Again I went to eBay and was able to find one that worked. It's not ideal, as the bulb isn't frosted so it's more of a uni-directional light, but it's pretty bright and makes the console usable again.

That leaves the glove box lamp. And boy, did that ever kick me in the backside. After struggling with a lot of popped fuses over a few weeks' worth of fiddling, it turns out that the stock glove box lamp holder does NOT like LED bulbs. At all. However, with the help from the message board, I was able to "fool" a bulb into working by covering up one side of the contacts. That was actually the very last bulb to get converted on the whole car.

Total so far: ~US $180. (Starting to hurt).


At this point the car was about 70% converted and I was pretty happy with the results. But the hardest part was still ahead: getting the brake lights and turn signals to work with LEDs, and without killing anything in the process.

LED Flasher

I had heard some things about this whole deal, and in the end they turned out to be mostly true. In order for LED turn signals to function like an incandescent setup, you will need an electronic flasher, and preferably one made for LED bulbs. The new flasher will have a ground wire coming off it, and that wire will absolutely need to be grounded before the flashing can occur with LEDs. Fortunately there are a few spare screws hanging around the fuse panel area that go right into direct metal. That's where I put the ground. The flasher was US $7 from eBay and it's round, just like stock. I know there are some square ones that could work with wire extensions but don't do that unless you have to. You will not need to change the 4-way flasher, by the way.

(Interestingly enough, with the new LED flasher installed, I tried the incandescent bulbs first and they still worked fine. Good to know in case you ever need to change them back or change out a dead bulb when you're on the road, or if you're mixing LED and incandescent bulbs in your particular setup.)

Also, I'd heard that taillight bulbs were the trickiest. Most people want you to believe that the "tower" bulbs are what you want. But I wasn't so sure because the ones I tried were rather unimpressive, and not very bright to boot, despite their high brightness ratings. I decided to try the Sylvania/Philips bulbs because so far, they were doing a great job at everything else.

What turned out to be semi-not true is the need for any inline resistors. In general, older cars like ours don't need them; however, in the case of light bleed—where even with the lights off there's still a faint residual luminance from the bulbs—then resistors might be needed. More on this below.

So I got my amber 1157 LEDs for the front turn signals and tried them...very nice, and they flashed just like usual. Again, I got the Sylvania/Philips bulbs in the white package. The ZEVO ones are a little weird looking and I didn't really care to try them.

LED Bulbs

With the front of the car mostly done, it was time for the rear brake/turn signal bulbs. I was sweating on those, because of the all-or-nothing, when you're dropping US $60 on the bulbs, you expect them to work like you hope they will. Well, they turned out pretty awesome. The red Sylvania/Philips 1157 LEDs are very bright. I am pretty happy with them, and although I wish there was more of a difference between the dimmer and brighter flashing, I'm not about to go looking for different ones right now. They're doing their job just fine.

The car, at this point, is about 95% done. All that's need now is LED headlamps. But do those even exist?

Total so far: ~US $267. (Holy moley).


It turns out that, yes, LED headlamps do exist. This is the standard 4x6 sealed beam style, and if you go on eBay or Amazon, you'll find an absolute boatload of them for sale. But are they any good? I've seen different ones in real life and looking at them from outside the car, they sure seem pretty bright. But you never know until you actually drive the car at night to figure out if it's going to work.

Most of these headlamps look okay. Some are gimmicky. A good majority of them don't have a good warranty, which means they'll likely die prematurely, which means I wasted money. Some are completely sealed up...again, that's fine but I don't want something that gets thrown away.

My goal here was to find stock-looking housings with replaceable LED bulbs. Sounds easy, right? Oh it's easy in your head...and then you try to find them. Not so fun. I mean, I could buy stock-looking H4-style housings and put LED bulbs in them. But then you have H4 wiring to deal with. I'm too old for that sort of thing. I want a well thought-out solution.

LED Bulbs

Which one is stock, and which one is LED?

Fortunately I found them after digging for weeks. The winners are from Octane Lighting. It's nearly impossible to tell these H4-style LED housings from stock. And the light say it's like daylight is pretty accurate. The bulbs are pre-wired for older cars so not only can they get replaced if necessary, they won't require fiddling around with the wire harness or require an adapter harness. The warranty is pretty good, too.

A really unique feature of the bulbs are the built-in cooling fans. Each bulb has one, and when you turn the lights on they whir and whir like a 1996 Windows laptop. Seriously, I have no idea if they even could get that hot, but it's nice to know they've got some assistance in any case.

One thing I discovered is that these particular LED headlamps put out the same general side-to-side pattern as the stock headlights, but the they tend to aim pretty high. You have to adjust them almost all the way down to get them correct enough. I'm still fiddling with the adjustments but at least oncoming cars aren't blinded anymore.

LED Bulbs

LED on the left, and the rest are stock.

LED headlights are just awesome and make a huge difference in visibility. These ended up being around US $40 each, which isn't cheap but have you priced regular sealed beams lately? They're approaching US $15 each now and you can't even replace bulbs in those. These ended up being a relative bargain in that respect, and for me it was the best decision.

If you are switching to LED headlamps and try different ones, please let us know about your experience. There is no "right" or "wrong" here, just whatever works for your preferences and your budget.



So now the '84 has a really modern lighting feel, and such usable light that I wonder how I'd put up with the old lighting for so long. It turns out that technology had to catch up to our lifestyles first, and in doing so it got pretty reliable in the process.

That being said, what I really wish is that Sylvania/Philips or some other major brand-name manufacturer would start marketing a "nostalgia" line of bulbs that are in the 4000K light range. That way, we could have modern LED bulbs but in the same yellower color range as stock (3500-4000K), with none of the disadvantages. I mean, sure, you can find 4000K bulbs on eBay but will they put out a good light pattern? Will they start flashing after awhile, as some people report? Will they last for a long time? Do they even have a warranty? That's why a major brand name needs to step in. Marketing that to people with old muscle cars would be an easy task. Even putting together conversion kits could be a thing. It sure beats piecing it together like I had to do.

Alas, I don't know if there's much of a market for some of the odd bulbs in our cars, at least for a good name brand. I really, really wanted to go all Sylvania/Philips with this conversion but it just wasn't possible.

Amazingly, most of the bulbs marked as 6000K actually were in that range. Sure, a few of the eBay ones were bluer, but it didn't really matter in the overall scheme of things. Getting a consistent color range across an entire car is now mostly long as you like bluish white.

There is a slight amount of light bleed in the taillights when the headlights are off and the car is running. It's not annoying and actually photographs way worse than it looks in real life. And it doesn't affect performance as far as I can tell. I've been told that the taillight bulbs might need inline resistors to resolve the issue, and that makes perfect sense to me. When time allows I will definitely experiment with them and report back here.

Thus far, I've notice no interference with the radio when the lights are on (another warning from Teh Intarwebs) although I haven't really put it to the test that much. Also, none of the bulbs flicker or have had any issues staying lit for extended periods. That's because of quality control by Sylvania/Philips. I suspect if any bulbs start going, they're going to be the eBay-bought ones.

Lastly, Octane Lighting doesn't sell any 5000K headlamp bulbs. Maybe one day they will. Or maybe someone else will make them in H4-style, and I can just swap them out. But until then I'll be happy with these.


UPDATE 1: Recently, the car site Jalopnik ran an article about putting quality LED bulbs in your car, entitled Why You May Want To Buy $10 LED Bulbs Even If $3 Ones Are Brighter. It basically reaffirms what I discovered in my own conversion and is well worth the short read.


If you've read the article thus far, there's no real need to rehash things for the '86 as the bulbs are almost all the same on that car as well. Well, it doesn't have a dome light (duh). But there are door courtesy lights and the rear reading lights that got turned into entry lights, so I had to replace those.

LED Bulbs

A dramatic difference in visibility.

Also, the convertible has AutoMeter aftermarket gauges and I have to say that I've always hate, hate, HATED the stock incandescent bulbs in them. They made the gauges practically unusable for me. Well, after some Sylvania/Philips 194 LEDs, I'm happy to say that they are now just awesome. Very bright, details really pop out, and they're much easier to see at a glance. Couldn't be more pleased. I went ahead and replaced the turn signal, high beam, and other indicators with LEDs in this car, by the way.

One of my main areas of concern with the convertible was how the LEDs were going to affect the sequential turn signal kit. I've been using the Cougars Unlimited kit since 1997 and it has never failed me. But I know LEDs can throw things into chaos if not done properly. Fortunately, Vic the owner is still around and a few quick emails to him got me on the right track. Instead of replacing my main sequential electronic unit, I just had to buy an add-on box to take care of the resistors, and a custom-built electronic flasher unit. These were both not cheap but they were still cheaper than a completely new full LED sequential box, and they were both plug and play. Couldn't have been simpler. Again I used the red Sylvania/Philips 1157 bulbs for the taillights.

Here is a view of the front turn signals, along with the cornering lamps:

So now, as the French say, the piece of resistance: the headlights.

To say I wanted a major cool factor to them would be an understatement. And I got them. Again from Octane Lighting, behold:

LED Bulbs
LED Bulbs

The halos are LED and are nearly identical to the style used on OEM vehicles today, meaning they're high quality with consistent light flow and no cold spots. You can wire them in however you want, but I just put them on a switch. Some people like to use them for daytime running lamps and that's fine also. I went with the 6K white halos, but Octane has all kinds of different colors if you so wish. (It would be cool to have amber ones for turn signals, though. Just saying).

The bulbs themselves are similar to the ones in the '84. These H4 housings are diamond cut with clear outer lenses and a chrome bulb cap. They look awesome in the daytime as well as at night. These bulbs have similar cooling fans along with braided straps on the back to further help with heat dissipation. There's kind of a lot going on behind the scenes, meaning between the header panel and radiator core support, as this kit has a lot of wiring and the braided straps and the inline resistor boxes. I was able to zip-tie them up out of the way for the most part.

Going off-script, I treated myself to a new LED clear/smoked third brake light for the trunklid, from a Chevy Blazer. Also got a new "hot rod"-style LED light for under the hood.

I actually worked on both cars simultaneously for the LED conversion. It didn't cost any less to do the convertible fact it was more, because the headlights were more expensive. For the convertible I'd venture to say the overall total spent was around US $550.

So...two cars, nearly US $1000 spent on things I really did not need to have. In the end, was it worth it?


Every penny.*

* Overall, I suppose that had I been pinching pennies, I could have likely gotten a majority of the bulbs cheaper on eBay or Amazon. They might have been okay, might have been in the correct color range, might last as long as these. There were a lot of unknowns going that way. You may or may not have a similar experience.


Hugh sent us these photos of his '83 converted over to LED headlamps, the common variety that's found on eBay:

Hugh's LED Conversion
Hugh's LED Conversion
Hugh's LED Conversion

Hugh said that last photo was with the headlight covers on...that's how bright they are!

We'd like to hear from you if you've also done an LED upgrade—let us know what you used, where you got the bulbs, how you like them, etc. and we'll be happy to share your experience on this page. We encourage you to send photos as well, even though we know they don't always photograph correctly. That's okay, we'd just like a visual representation of your work.