DIY LED Daytime Running Lamp (DRL) in 944 Turbo fog/driving light
07-01-2014, 12:48 PM
#1
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Thread Starter
DIY LED Daytime Running Lamp (DRL) in 944 Turbo fog/driving light
The "empty" (inboard) spot inside each 944 Turbo/S2 fog light enclosure (US models) looks like a good candidate for modern LED Daytime Running Lamps (DRLs). I'm aware that parts of the rest of the world have an additional reflector and high beam bulb in that location.
Finished Product - Installed on my 944:
Note: fog lights use 3000K (slightly yellow) 55W Halogen H3 bulbs.
After searching the entire Interwebs and not finding one single photo of anything similar, I decided to not only do the project but to document it and post a how-to here.
The goal is to retain and not modify in any way all original US-market fog light functionality, including flash to pass when headlight switch is off.
Additionally, I wanted the following behavior:
I have designed a relay-based solution for controlling DRL behavior, but I'm working on a transistorized one. Any electrical engineers want to help?
What follows is a (mostly) photo tutorial of the work as I did it.
Before:
Notice one lens is badly pitted - see my Polishing Tutorial Here
Tools You'll Need:
The LEDs:
These are "Eagle Eye" style LEDs. Each is 3W (plenty bright) and designed to be connected directly to 12V (so no series wiring or load resistors). I chose white (~6000K) ones with aluminum housings, though different wattage, color temps, and colors (red/amber/purple/whatnot) are available. I got a dozen even though my design only called for ten LEDs. (It was cheaper to order 2x 6-packs than 10x individuals or 5x 2-packs, plus then I have a couple spares.)
Several of mine arrived with the wiring reversed - red wire was negative and black was positive. LEDs are polarized, so they won't light if current tries to flow the wrong way - it is a diode after all.
Test each LED for polarity prior to finishing your wiring.
Carefully Plan Your Layout
Confirm Your Layout
It's very easy to get the plastic insert flipped around - the left and right fog light housings use the same plastic insert in the "driving light" (empty) location. My design could be installed upside down in the other enclosure - ie, correct orientation in the left-side housing would be upside down if placed in the right-side housing.
Drill
The plastic you are drilling into is old and probably brittle. I started with a small bit - maybe 1/8" - and worked my way up by 1/64" increments all the way to 7/16" (slightly larger than the mounting shaft on my LEDs).
This is definitely a time to "let the tool do the work" - don't push hard, and be careful about the drill bit "biting" and tearing/cracking the plastic. I also "reamed" the hole after each new drill size to make the next one slightly easier. Be especially careful with larger drill bits - the tendency to "bite" increases with each size over about 1/4"
If you go slow and take your time, you probably won't have any problems.
Mount LEDs
Wiring
If using heat shrink tubing and a heat gun, be VERY CARFUL about overheating the plastic insert. I made the mistake of using the heat gun with the plastic insert mounted inside the lens. The heat build up was enough to warp the insert, rounding it out and making it not fit.
I was able to unwarp mine with the application of more heat, pressure from my hands, and patience. But you can avoid the problem by simply removing the insert and making sure you are careful about where you are aiming the heat gun.
Finished
As you can see, the US Driver's side lens (vehicle left side, pictured on the right) is significantly pitted.
See my Polishing Tutorial Here
I will post a drawing of my electrical control mechanism if anyone is interested - it is cumbersome and uses a total of five relays (would only need three if I didn't want to individually turn off the corresponding DRL when the turn signal is active). I'm working on a transistor-based solution instead.
I hope some of you find some inspiration to do this project for yourself.
Finished Product - Installed on my 944:
Note: fog lights use 3000K (slightly yellow) 55W Halogen H3 bulbs.
After searching the entire Interwebs and not finding one single photo of anything similar, I decided to not only do the project but to document it and post a how-to here.
The goal is to retain and not modify in any way all original US-market fog light functionality, including flash to pass when headlight switch is off.
Additionally, I wanted the following behavior:
- Daytime Running Lamps (DRLs) on automatically when the car is running (and off when cranking - KL.X in the Porsche electrical schematics)
- DRLs off automatically when fog lights are on - DRLs would provide too much scatter light (especially through the high-beam lenses) for actual use in the fog
- Flash to Pass (FTP) using DRLs when fog lights are on, regardless of whether headlights are down or up (DRLs are off when fogs are on, so they can "flash")
- DRLs on with high beams
- with headlight switch off and fog light switch off, BOTH fog light and DRL's will activate with FTP (since DRLs activate with high beams)
- when turn signal is on, corresponding DRL turns off (for easier visibility of turn signal, and because lots of newer cars seem to do that - I think it's cool).
I have designed a relay-based solution for controlling DRL behavior, but I'm working on a transistorized one. Any electrical engineers want to help?
What follows is a (mostly) photo tutorial of the work as I did it.
Before:
Notice one lens is badly pitted - see my Polishing Tutorial Here
Tools You'll Need:
The LEDs:
These are "Eagle Eye" style LEDs. Each is 3W (plenty bright) and designed to be connected directly to 12V (so no series wiring or load resistors). I chose white (~6000K) ones with aluminum housings, though different wattage, color temps, and colors (red/amber/purple/whatnot) are available. I got a dozen even though my design only called for ten LEDs. (It was cheaper to order 2x 6-packs than 10x individuals or 5x 2-packs, plus then I have a couple spares.)
Several of mine arrived with the wiring reversed - red wire was negative and black was positive. LEDs are polarized, so they won't light if current tries to flow the wrong way - it is a diode after all.
Test each LED for polarity prior to finishing your wiring.
Carefully Plan Your Layout
Confirm Your Layout
It's very easy to get the plastic insert flipped around - the left and right fog light housings use the same plastic insert in the "driving light" (empty) location. My design could be installed upside down in the other enclosure - ie, correct orientation in the left-side housing would be upside down if placed in the right-side housing.
Drill
The plastic you are drilling into is old and probably brittle. I started with a small bit - maybe 1/8" - and worked my way up by 1/64" increments all the way to 7/16" (slightly larger than the mounting shaft on my LEDs).
This is definitely a time to "let the tool do the work" - don't push hard, and be careful about the drill bit "biting" and tearing/cracking the plastic. I also "reamed" the hole after each new drill size to make the next one slightly easier. Be especially careful with larger drill bits - the tendency to "bite" increases with each size over about 1/4"
If you go slow and take your time, you probably won't have any problems.
Mount LEDs
Wiring
If using heat shrink tubing and a heat gun, be VERY CARFUL about overheating the plastic insert. I made the mistake of using the heat gun with the plastic insert mounted inside the lens. The heat build up was enough to warp the insert, rounding it out and making it not fit.
I was able to unwarp mine with the application of more heat, pressure from my hands, and patience. But you can avoid the problem by simply removing the insert and making sure you are careful about where you are aiming the heat gun.
Finished
As you can see, the US Driver's side lens (vehicle left side, pictured on the right) is significantly pitted.
See my Polishing Tutorial Here
I will post a drawing of my electrical control mechanism if anyone is interested - it is cumbersome and uses a total of five relays (would only need three if I didn't want to individually turn off the corresponding DRL when the turn signal is active). I'm working on a transistor-based solution instead.
I hope some of you find some inspiration to do this project for yourself.
Last edited by ddieringer; 07-01-2014 at 07:10 PM.
07-01-2014, 03:22 PM
#3
I like it, i just run the fogs as my DRLs when appropriate at the moment. I have the euro lights in my car so i have driving lights in that spot, but i've thought about ways to run something similar on the car. . They are wired to kick on from the high beam relay.
PS great first post, welcome to the forums.
PS great first post, welcome to the forums.
07-01-2014, 05:24 PM
#5
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Thread Starter
Thanks for the feedback so far everyone.
The clear turn signal lenses came from a German seller on Ebay - shipped the same day and had them in less than a week (no affiliation, yadda yadda, just happy customer).
With clear lenses, you'll need amber bulbs or your turn signals will blink white - may not be legal or particularly safe. An amber 1157 is a direct physical replacement for the single clear 7xxx bulb that was behind each original amber turn signal lens (don't remember the exact number off the top of my head, and I don't want to contribute unnecessarily to Internet wrongness by guessing it here.) I know amber LED 1157 replacements are available, some of them with built in load balancing resistors or other construction so your flasher relay still blinks at the proper speed. I didn't want to mess with that, so I went with a regular 20-something watt amber 1157.
As far as power consumption for the DRL's, here's how I figured it out:
Each LED says it is 3 Watts, and I have five in each housing. That's a total of 15W per side or 30W total.
Many people have probably at least heard of "Ohm's Law", V=IR (Voltage = Current [amps] x Resistance [Ohms]). Given two, we can solve for the third using algebra.
Similarly, there is the "Power Law", P=IV, or Power [Watts] = Current [amps] x Voltage. We know power (15 Watts per side) and voltage (12V, or more like 13.8V when the car is running).
Unless I have a fundamental misunderstanding, we can solve the equation as follows:
- P=IV, or I=P/V
- I = 15W/13.8V, so ~1.1A per side or ~2.2A total.
So not much current draw. However, I don't know how the LEDs will like living in the same physical housing as 55W halogen bulb. That halogen bulb probably gives off a lot of heat, and electronics (like LEDs) don't really like being hot. Longevity remains to be seen.
I thought about a diffuser of some sort inside the housing, but I actually like the look of the LEDs. Of course, when even modestly modifying a car, it's all about what we like ourselves. I hope someone takes this idea, improves it in some way, and makes it their own.
The clear turn signal lenses came from a German seller on Ebay - shipped the same day and had them in less than a week (no affiliation, yadda yadda, just happy customer).
With clear lenses, you'll need amber bulbs or your turn signals will blink white - may not be legal or particularly safe. An amber 1157 is a direct physical replacement for the single clear 7xxx bulb that was behind each original amber turn signal lens (don't remember the exact number off the top of my head, and I don't want to contribute unnecessarily to Internet wrongness by guessing it here.) I know amber LED 1157 replacements are available, some of them with built in load balancing resistors or other construction so your flasher relay still blinks at the proper speed. I didn't want to mess with that, so I went with a regular 20-something watt amber 1157.
As far as power consumption for the DRL's, here's how I figured it out:
Each LED says it is 3 Watts, and I have five in each housing. That's a total of 15W per side or 30W total.
Many people have probably at least heard of "Ohm's Law", V=IR (Voltage = Current [amps] x Resistance [Ohms]). Given two, we can solve for the third using algebra.
Similarly, there is the "Power Law", P=IV, or Power [Watts] = Current [amps] x Voltage. We know power (15 Watts per side) and voltage (12V, or more like 13.8V when the car is running).
Unless I have a fundamental misunderstanding, we can solve the equation as follows:
- P=IV, or I=P/V
- I = 15W/13.8V, so ~1.1A per side or ~2.2A total.
So not much current draw. However, I don't know how the LEDs will like living in the same physical housing as 55W halogen bulb. That halogen bulb probably gives off a lot of heat, and electronics (like LEDs) don't really like being hot. Longevity remains to be seen.
I thought about a diffuser of some sort inside the housing, but I actually like the look of the LEDs. Of course, when even modestly modifying a car, it's all about what we like ourselves. I hope someone takes this idea, improves it in some way, and makes it their own.
Last edited by ddieringer; 07-01-2014 at 05:40 PM. Reason: clarification
