Calling All Electrical Gurus for Custom DRL/Wiring/LED project
06-21-2011, 08:02 PM
#1
Calling All Electrical Gurus for Custom DRL/Wiring/LED project Could anybody give me an idea of how I should go about wiring this up?
Here is the stock wiring, as seen from the bulb side:
Here is the lamp I want to use (note: only two wires - ground and hot):
- I want to replace the 3157 front turn signal lights in my US-spec '99 Pontiac Firebird with some 10W LED fixtures.
- I want them to work with the stock DRL harness so that when I hit the turn signals, they flash dim and bright, just like a 3157 bulb would (if possible).
- I am not sure how the DRL module works, so I really don't know how I would be able to wire this up properly.
- If bright/dim is not feasible, what are my options?
Here is the stock wiring, as seen from the bulb side:
Here is the lamp I want to use (note: only two wires - ground and hot):
Last edited by ZexGX; 06-21-2011 at 08:15 PM.
06-21-2011, 09:24 PM
#2
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I'm not really sure about any of this, but just spitballing:
One thing I am sure about is that the car sends 12V to both the bright and the dim portions of the 3157 bulb.
I am assuming that the brightness of the led fixture is controlled by the voltage you put across it. What is the highest voltage it can take? One possibility is that you use some sort of transformer, or possibly just a well-placed resistor, which simply decreases the voltage that would normally be going to the dim portion, then simply splicing both hot wires into the one hot on your fixture. That way, when the bright portion is normally lit, the LED sees a higher voltage, and vice versa. My only concern would be that when the blinkers are active, both the bright and the dim are lit simultaneously, which, if you aren't careful, may overload the LED (hence my question about the LED's voltage capability).
Again, just bouncing some ideas. I don't know for sure that any of this would work. If my roommate were here for the summer, I would ask him (he's an electrical engineer), but for now, that's all I've got. Good luck!
One thing I am sure about is that the car sends 12V to both the bright and the dim portions of the 3157 bulb.
I am assuming that the brightness of the led fixture is controlled by the voltage you put across it. What is the highest voltage it can take? One possibility is that you use some sort of transformer, or possibly just a well-placed resistor, which simply decreases the voltage that would normally be going to the dim portion, then simply splicing both hot wires into the one hot on your fixture. That way, when the bright portion is normally lit, the LED sees a higher voltage, and vice versa. My only concern would be that when the blinkers are active, both the bright and the dim are lit simultaneously, which, if you aren't careful, may overload the LED (hence my question about the LED's voltage capability).
Again, just bouncing some ideas. I don't know for sure that any of this would work. If my roommate were here for the summer, I would ask him (he's an electrical engineer), but for now, that's all I've got. Good luck!
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06-28-2011, 07:55 AM
#9
First check your state laws... many states don't allow white turn signals. You may also have problems because of how blue a 7000K lamp appears.
You'll have to come up with some wiring mods to make the single bulb do dual duty as parking lights (dim) and DRL/turn signals (bright). The OEM system uses two separate power wires connected to separate filaments in the bulb to accomplish this. Both of the wires provide a full 12V power source and it is the bulb's filament design that makes the two different light intensities.
There are three wires at the original socket... black for ground, brown for parking light power, and blue for DRL/turn signal power. Connecting to the blue wire will give you DRL and turn signal functionality but no parking/running lights when the headlights are on. That may be enough since the dim filament is only used when the headlights are on and is mostly redundant.
You could assemble some resistors and a couple of diodes to connect the brown wire to the lamp in addition to the blue wire in such a way that the voltage is reduced to about 4 volts (maybe even less) and there is no backfeed between the wires. That would give you dim output for parking lights. The normal output of the incandescent bulbs is 3 candlepower on the dim side and 32 cp on the bright side - you may find that you can't reduce the voltage enough to make the LED come on at only 10% of full brightness.
Some other notes... a 10W LED lamp will be much brighter than the OEM bulbs - even a 7W LED replacement bulb is somewhat brighter than a standard bulb. Also, you will need either a special LED flasher or a load equalizer to make the turn signals flash properly.
Finally, I agree with wssix99 that LED replacement bulbs would be a better way to go. I replaced my lamp housings several years ago because of cracks caused by overheating from the bulbs. At the same time, I replaced the bulbs with 7W LED bulbs because of the reduced heat they produce. I have not had a failure or cracked lens since then. No modifications were necessary except for the LED flasher.
You'll have to come up with some wiring mods to make the single bulb do dual duty as parking lights (dim) and DRL/turn signals (bright). The OEM system uses two separate power wires connected to separate filaments in the bulb to accomplish this. Both of the wires provide a full 12V power source and it is the bulb's filament design that makes the two different light intensities.
There are three wires at the original socket... black for ground, brown for parking light power, and blue for DRL/turn signal power. Connecting to the blue wire will give you DRL and turn signal functionality but no parking/running lights when the headlights are on. That may be enough since the dim filament is only used when the headlights are on and is mostly redundant.
You could assemble some resistors and a couple of diodes to connect the brown wire to the lamp in addition to the blue wire in such a way that the voltage is reduced to about 4 volts (maybe even less) and there is no backfeed between the wires. That would give you dim output for parking lights. The normal output of the incandescent bulbs is 3 candlepower on the dim side and 32 cp on the bright side - you may find that you can't reduce the voltage enough to make the LED come on at only 10% of full brightness.
Some other notes... a 10W LED lamp will be much brighter than the OEM bulbs - even a 7W LED replacement bulb is somewhat brighter than a standard bulb. Also, you will need either a special LED flasher or a load equalizer to make the turn signals flash properly.
Finally, I agree with wssix99 that LED replacement bulbs would be a better way to go. I replaced my lamp housings several years ago because of cracks caused by overheating from the bulbs. At the same time, I replaced the bulbs with 7W LED bulbs because of the reduced heat they produce. I have not had a failure or cracked lens since then. No modifications were necessary except for the LED flasher.
06-29-2011, 11:30 AM
#11
Hmmm... Ok. Does the GM DRL module "pulse" the power signal to the lamps? I've noticed that when looking at some other LEDs through a camera, they appear to flash - at a rate faster than the human eye can detect... Is there a way to fix that? That would cause an issue with longevity, right?
No, white will not cause any issues. It is legal in my state (for DRLs and turns signals). I have been running clear tungsten bulbs in my DRLs for years. Many GM trucks have them around here... Oh, and what do all new Audi's have when it comes to front running lights? Yup, you guessed it... White LEDs.
I kinda want to use an amber LED drop-in though for a different approach to a DRL project (halos).
I kinda want to use an amber LED drop-in though for a different approach to a DRL project (halos).
06-29-2011, 11:33 AM
#12
No, GM does not use PWM (Pulse Width Modulation) with any of their turn signal based DRL setups (like F-bodies). They do use it for vehicles that run the headlights as DRLs. PWM can be very bad for LED bulbs but our DRLs get a full 12V power supply.
06-29-2011, 02:02 PM
#13
No, white will not cause any issues. It is legal in my state (for DRLs and turns signals). I have been running clear tungsten bulbs in my DRLs for years. Many GM trucks have them around here... Oh, and what do all new Audi's have when it comes to front running lights? Yup, you guessed it... White LEDs.
Here's the federal reg for auto lamps. Its a bit of a sleeper to read through all of this, but the key bits of info for this problem are all in Table III and Table IV at the very bottom of the regulation: http://ecfr.gpoaccess.gov/cgi/t/text....2.7.8&idno=49
Further up in the reg, it also gets in to viewing angles, luminosity, etc. if you want to match up your LED's to the other specs.
06-29-2011, 02:06 PM
#14
Its not a state thing - its a federal law. The turn signals need to be amber, but the parking lights can be white. (So, the Audi's are kosher. You can accomplish an amber signal by an amber bulb in a clear lens or a white bulb with amber lens.) Part of the reason things are this way is because a flashing white light is an international distress signal.
Here's the federal reg for auto lamps. Its a bit of a sleeper to read through all of this, but the key bits of info for this problem are all in Table III and Table IV at the very bottom of the regulation: http://ecfr.gpoaccess.gov/cgi/t/text....2.7.8&idno=49
Further up in the reg, it also gets in to viewing angles, luminosity, etc. if you want to match up your LED's to the other specs.
Here's the federal reg for auto lamps. Its a bit of a sleeper to read through all of this, but the key bits of info for this problem are all in Table III and Table IV at the very bottom of the regulation: http://ecfr.gpoaccess.gov/cgi/t/text....2.7.8&idno=49
Further up in the reg, it also gets in to viewing angles, luminosity, etc. if you want to match up your LED's to the other specs.
Cited from the California Vehicle Code http://dmv.ca.gov/pubs/vctop/d12/vc24953.htm:
24953. (a) Any turn signal system used to give a signal of intention to turn right or left shall project a flashing white or amber light visible to the front and a flashing red or amber light visible to the rear.
Last edited by ZexGX; 06-29-2011 at 02:12 PM.
06-29-2011, 02:13 PM
#15
I believe federal law trumps state law in this matter but you're right - for all practical purposes, white turn signals should not get you in trouble in California. Florida law also allows white but I believe Maryland and Texas follow federal amber-only requirements. I haven't looked at many other states.
That still leaves the question of "why not just use an amber LED bulb in the OEM housing?" It's easy, it's legal, and it worked well for me as far as preventing the cracks and water infiltration.
That still leaves the question of "why not just use an amber LED bulb in the OEM housing?" It's easy, it's legal, and it worked well for me as far as preventing the cracks and water infiltration.
06-29-2011, 02:18 PM
#16
Guess I should look into which types of resistors and diodes to add to the wiring harness.
