Thoughts on retrofiting LED tail, marker, and brake lights

Recently, I replace the taillight and my license plate light with a set of LED light. The chief reason is that on the Subaru, the marker light appears to burn out a lot. I am looking through my service record, and there's a lot of market light replacements. Of course, this may be a electric issue, but replacing them with a LED is probably a good test.

Based on some reading, there were warning that the LED light should be visible at different angle and that you should match the color of the lens. I installed red led for taillight and white led for license plate light. I used some dielectric grease as advised by the store employee that I purchased it from.

What I have observe is that the LED that I purchased look more like a frosted version of the original bulb. In other LED, it often look like a rod with lots of led lighting elements. Frankly, it's probably looks like that underneath the bulb. The light put out is higher than the in incandescence bulb, but the LED is new while the old bulb is old, so maybe the old bulb would have been brighter out of the box.

What I did not like in the taillight is that I can see a visible bulb when lighted. In the old bulb, the light sort of blends in while in the new one, you can clearly see a single point of light in the center. Because I used the red bulb, the light at least look red for the taillight. For the license plate, there were no issue except that the light is again brighter and whiter.

The outback has separate brake and taillights. I notice that on some vehicle, the light are combined. In those cases, I am wondering if there may be an issue with the LED. May be there is less separation between the brake and non-brake.

I wonder about temperature, too. The bulb is small and don't have a lot of cooling area, but perhaps for taillight the amount of heat generate is small. I wonder if the outside temperature is 100F, would the LED be dimmer.

Paul

paulsiu said:

Based on some reading, there were warning that the LED light should be visible at different angle and that you should match the color of the lens. I installed red led for taillight and white led for license plate light.

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Good, but did you carefully compare the performance of the original and LED bulbs as described in this post?

I used some dielectric grease as advised by the store employee that I purchased it from.

This probably won't hurt anything, but it was not a valid piece of advice from the store employee -- all it did was increase his sales.

What I have observe is that the LED that I purchased look more like a frosted version of the original bulb.

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What exact LED bulb did you buy? Please be specific.

The light put out is higher than the in incandescence bulb

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That could be a problem. Remember, there has to be clear and definite contrast between the low-intensity tail light and the high-intensity brake light. And this contrast is defined by legal regulations in terms of intensity ratios; it's not just a question of whether you (or anyone else) personally think it looks OK.

What I did not like in the taillight is that I can see a visible bulb when lighted. In the old bulb, the light sort of blends in while in the new one, you can clearly see a single point of light in the center.

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You put in a type of light source other than what the lamp was designed for. It's going to look different.

I wonder if the outside temperature is 100F, would the LED be dimmer.

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Could be.

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-Virgil- said:

Good, but did you carefully compare the performance of the original and LED bulbs as described in this post?

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Yes, I left one light and attempted to view it from all sides in daylight, then later at night.

-Virgil- said:

I used some dielectric grease as advised by the store employee that I purchased it from.

This probably won't hurt anything, but it was not a valid piece of advice from the store employee -- all it did was increase his sales.

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I actually google this while I was in the store since the employee was unable to give a reasonable explanation. The idea appears to be to reduce corrosion on the contact. There are some post for and against, but I figure a little wouldn't hurt.

-Virgil- said:

What exact LED bulb did you buy? Please be specific.

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I threw out the package, so I don't remember. I would need to look it up. The package was a bit confusing.

-Virgil- said:

That could be a problem. Remember, there has to be clear and definite contrast between the low-intensity tail light and the high-intensity brake light. And this contrast is defined by legal regulations in terms of intensity ratios; it's not just a question of whether you (or anyone else) personally think it looks OK.

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The light come in high intensity and low version. This is the low one.

-Virgil- said:

You put in a type of light source other than what the lamp was designed for. It's going to look different.

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Probably the case.

Actually the point of the post was that the article you mentioned should probably be extended to talk about dual purpose bulbs. On some cars, the bulb appears to be dual filament or something. If you turn on the taillight, it glows red, but when you press on the brakes it glows with a higher intensity. The lack of difference may be an issue.

Paul

paulsiu said:

On some cars, the bulb appears to be dual filament or something. If you turn on the taillight, it glows red, but when you press on the brakes it glows with a higher intensity. The lack of difference may be an issue.

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The lack of difference is a common issue in my experience, among other things. Here is my experience with some LEDs in a few vehicles. Not all of my observations can be generalized across all vehicles on the road, but some aspects automatically disqualify the LED from being safe to use in any vehicle (like the fact that the particular Philips below shuts off when hitting the brakes--neat function!)

1) Sylvania, non-Zevo LED 7443: practically has no "major filament" function. In other words, it does not get brighter when you hit the brakes.

2) Philips 12840REDB2/Intense Red Vision 3157 LED (recommended on this forum): the bulb's "minor filament" lights up fine, but when you hit the brakes, the entire bulb shuts off. It goes completely dark when you hit the brakes instead of energizing the "major filament." Neat function! Also, it does not successfully illuminate the side marker portion of the taillamp (the car uses a 3157 bulb to function as a brake lamp and to illuminate the side marker).

3) Sylvania Zevo LED 3157: has distinguishable "minor" and "major filament" functions, but doesn't fill brake lamp compartment as well as a regular incandescent bulb. And it doesn't illuminate the side marker.

I returned them all before even taking my car on the road. I wasn't going to put myself and others at risk by using a crappy LED bulb. (Well, admittedly, I didn't return the non-Zevo 7443 immediately, as the store was sold out of incandescent 7443 bulbs and it was either drive with no taillight bulb or drive with a crappy LED taillight bulb).

Contrast between the running/brake lights is critical, IMO. Some cars with some housings do very well with some LEDs... For example, the 65 Olds 98 I had a few years ago, and my old Dodge Dynasty both did very, very well with the Philips LEDs that Dan Stern recommended, but the Volvo 940 wagon I had at the time was absolutely terrible with the same LEDs I used in the Oldsmobile.

It all boils down to how well does that LED work in that particular lamp. I'll also say that if it's a fresnel lens as opposed to a clear one, the Philips XtremeVision and the back-firing Sylvania Zevo (as opposed to the lower-tier offerings from both Philips and Osram Sylvania) appear to do as well, if not better than stock, provided it's a large enough reflector area. See: my Buick Roadmaster with the XtremeVision LEDs in the rear... Again, large reflector area, fresnel lens and it appears to have more even light distribution than stock, with more unscientifically, uncalibrated eyeball-measured contrast in the unscientific 25' 4-way flasher test...

Smaller reflector bowls (see: my Volvo) and clear lenses don't do so well with LED swaps.

YMMV.

darksider415 said:

if it's a fresnel lens as opposed to a clear one, the Philips XtremeVision and the back-firing Sylvania Zevo (as opposed to the lower-tier offerings from both Philips and Osram Sylvania) appear to do as well, if not better than stock

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No. "Fresnel as opposed to clear" is not a correct division of lens types. Fresnel lenses are the ones that have round or linear prisms, often with a central bull's-eye, that are designed to look directly at the bulb's filament to gather, amplify, and focus the light. Fresnel lenses require a bulb that emits light directly toward the lens. Of the few legitimate LED bulbs on the market, only the older/discontinued Philips bulbs (like this and this) are compatible with Fresnel lenses for that reason.

Lenses that have flutes and pillows to spread/distribute light collected and amplified by a reflector dish behind the bulb are not Fresnel lenses. These types, however, can in some cases work with rear-firing LED bulbs because they don't depend on light going directly from the bulb to the lens.

There are also hybrid optics of various types: reflector dish + Fresnel lens, Fresnel optics + spreader/distribution optics, etc.

It is also not correct to generalize that "smaller reflector bowls and clear lenses don't do so well with LED swaps". Some of them do, some of them don't.