Switch to LED Daytime Running Lights

[Mobius]

A little background... I was looking for a way to get rid of the yellow turn signal lamps on my '03 EXT and came across the Silverstar 3157 bulbs. Put them in and they looked kind of nice. I wanted to switch my DRL's from "white" to amber because I like the look of the amber with Raven Black. So I swapped my DRLs to the silverstars also. That was almost a year ago. Recently I started to notice an ever so slight hazing on the inside of the lense assembly and suddenly realized that the Silver stars are too hot and are clouding my lenses. Not Good. So to prevent any further clouding I removed the Silverstars and replaced them with the 4114K listed bulbs.

Turns out, as many of you may know, that the GMT 800 body style has a voltage issue on the DRL's. They operate at closer to 14 Vdc rather that 12 Vdc. Which leads to shorter bulb life. So Sylvania came up with the 4114K which is rated to operate at 14V. But they are "white" (actually yellowish.) So I started looking into LEDs, but found out that due to the higher voltage in the DRL's, LED's are burning out in a month or so because at times the voltage can spike to over 15V, which burns up the LED. BTW, don't try to tell me it's because of "increased current." That's 100% impossible. Kirchoff's voltage law states that Voltage equals the product of Current and Resistance (V=I*R) Which means that voltage and current have an inversley proportionate relationship. Simply put, as the voltage goes up, the current goes down assuming the resistance remains the same. However, LEDs are NOT capable of higher than rated voltage for very long. When I measured the voltage on my truck I got from 14.03V to 14.56V depending on idle and starting.

So, what to do? The nice thing about Kirchoff's law is that you can limit the voltage applied to a load by inserting more resistance in the circuit. I got my LED's and ran them off a 12Vdc power supply and using a multi-meter, measured the current. it was about 77 milliAmps or 0.077 Amps. (compare that to the 2.1 Amps of the 4114K) I should insert here that I am an electrical engineer by trade. I wanted to limit the voltage in my DRL's to 12Vdc, so I needed about a 1.7V drop. Back to Kirchoff, 1.7Vdc/0.077=22 Ohms. So I took a trip to radio shack and purchased so 22 ohm, 1/2 watt resistors and some 15 ohms for good measure. (99 cents for 5 of each.) Opened up the headlight assembly, found the dark blue power wire going to the DRL's, clipped the wire, soldered in a single 22 ohm resistor, and plugged in my LED bulb. I checked the voltage again after installation and (this is where real world comes into play) found that my new LED's were getting 11.25V now instead of the 14V before. Why? I forgot to measure the initial voltage under load so the bulbs were probably getting more like 13V under load. Pulled the 22 ohm resistor, installed the 15 ohm resistor and BINGO! 11.89Vdc under load. So now my DRL's are LED bulbs operating at a livable 11.89Vdc.

HOWEVER, I am extremely dissappointed in how bright they are. I am going to search for something brighter. They are about 1/3 the brightness of the Silverstars. Course they draw 3.67% of the current and they do not generate any heat at all.

For reference, I got the 32 LED Matrix II LED's from www.autolumination.com. They are not "super bright" as they claim.

[Playdrv4me]

Hmm... I might try the orange bulb thing. Thats a good idea as mine is black too. Just gotta find some that wont overheat the housing.

[Mobius]

I have amber LED's now, but based on my calcs, I think the LEDs put out anywhere from 80 to 150 Lumens. Depending on the rated output of each. The Silverstar's are rated to be 300 lumens. So the LED's are DEFINITELY not any where as bright. But they have no heat whatsoever.

Here's the other problem, the only bulb that will last a very long time in the lamps is the 4114K which is "white." any other 3157 bulb will suffer premature failure due to the 14V issue. The long life bulbs, usually listed as 3157NALL, should last longer, but will probably not give you the 5000 hours they claim. I love the look of the amber DRL's with the black truck. Just check out a black CTS next time you see one drive by. A lot more distinctive than the plain "white."

I'll try to take some pics of the current DRL's to show how dim they are. My turn signals are still Silverstars, so you can see the difference.

Oh, and I know it was heat, cause the socket was slightly deformed and blackened from the heat. The turn signals are sqweaky clean, no heat.

[Playdrv4me]

Wouldnt your resistor idea theoretically work for the incandescents too? Thereby restoring the lifespan of the bulbs and not overheating the housing and socket?

[Mobius]

The resistor should restore the lifespan, but not the overheating. The lifespan is from putting 12V bulbs in a 14V circuit. The overheating is a wattage thing. I believe that the 4114K lights are something like 22 Watt bulbs. The Silverstars I had were more like 30 Watt. The standard bulbs burn pretty hot to start off, but the Silverstars hotter still. Remember, that that wattage is essentially the heat output of the bulb. Sure you get more light, but light energy is very inefficient in an incandescent bulb and you have to deal with all that heat generation also.

If you compare to the LED's, they are running at about 0.924 Watts. For all intents and purposes, there is no heat. Now go grab a 25Watt light bulb in your house... Then after you put ice on your fingers, you will understand the difference...LOL.

I think I should note that the resistor I installed is NOT the same as the "load equalizers" that you have to install when you change your turn signals to LED. This is completely different.

Modern turn signals monitor the current that is drawn by each bulb. The standard incandescent bulb is operating at about 2 amps. The LED bulbs draw more like 0.075 amps. Your vehicle sees this as a burned out bulb and "quick" flashes the turn signal to let you know. The "load equalizer" is a 50 Watt, 6 or 3 ohm resistor that draws nearly 2 Amps in parallel with the LED's and fools the vehicle into believing the bulb is intact. Down side is if the LED fails, you'll never know it. But they are supposed to last something like 100,000 hours as opposed to 1,000 for incandescent.

[benamaster]

I've had no problems using the AutoLumination or Super Bright LED's Tower style bulbs in the DRL spot. They've been there for over a year.

[Caddydude420]

Want to do us all a HUGE favor and post pictures?

[Mobius]

I've been talkinn with Autolumination via e-mail about the MAtrix. They say that the Light Tower II is visibly brighter. They also said they would take the Matrix Bulbs I have back in exchange for the Towers. I plan to do that.

What I've heard about the burn out is that it's common but obviously not guaranteed. What I wanted to do was guarantee it.

They also said that the circuitry in the Tower is designed to help prevent the burn out issue, but that the resistor is a good way to guarantee the life span of the bulb. Cool! They even sell a "led protector" which is designed to do what I did with my resistor. But mine cost 20 cents, theirs costs $2. Anyway, just food for thought.

[benamaster]

Yeah I really like the Light Tower over all the other bulbs. I can grab a few pictures tonight. They are super bright especially at night when you unlock the doors because thats the only time they come on at night and during the day they are almost as noticible as the regular bulbs but have that cool blue look compared to the ugly yellow.

[Mobius]

Got a picture of the lights. Had to turn on the hazards to get the DRL's and the turn signals on together. You can see the difference in light level. I plan to re-order the Light Tower II bulbs and will try to get a comparison picture.

[Mobius]

I got the new Tower II led's from Autolumination and it's a 100% improvement. Still not quite as bright as the Silverstars, but close enough. And the color is much closer to the Silverstars (more amber than yellow). Overall I'm pretty happy now. I'll get a picture when I get a chance to show the difference.

I am sold on the Amber DRL's with the Raven Black. I just like the look personally.

[Mobius]

Wow did that take a while to get back to this thread. If anyone was desperate to see the new LED bulbs, well, sorry. I completely forgot about it and didn't remember until the Foggy lenses thread came up. Anyway, I got a pic of the new Light Tower II's in my truck. I love them! Much better. Some day, when I'm feeling adventurous, I'll switch out the turn signals to LED too. Someday. Anyway here's the new pic:



And the old one just for comparison:

[2caddy23]

That looks really nice.

[8ball]

Looks nice.

[Ecko9885]