LED bulb replacement
03-19-2004, 08:36 PM
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LED bulb replacement
Has anyone replaced their brake lights with the LED bulbs (1156)? I did so today (by the way my car is still in storage with 3 feet of snow in front of the door). Anyway.... It all seems to work fine but the brake light message stays on in the pod area. You know the one where if you hit the brake it goes away after start-up. Any ideas on how to correct this situation? The brake lights look very cool now. More of a direct look compared to a reflective look.
03-19-2004, 08:54 PM
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I think you'll have to disable the LCM (lamp control module), Chucker.
The warning message is prompted by a voltage variance greater than a preset value (as occurs when one bulb is burnt out).
Because the current draw for LED lighting is much lower than that of traditional incandescent bulbs, the LCM will always think that the voltage variance is due to a burned out bulb, resulting in that always-on warning light.
The warning message is prompted by a voltage variance greater than a preset value (as occurs when one bulb is burnt out).
Because the current draw for LED lighting is much lower than that of traditional incandescent bulbs, the LCM will always think that the voltage variance is due to a burned out bulb, resulting in that always-on warning light.
03-19-2004, 09:09 PM
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Hey thanks guys. I love this board! I post a question and wham. A response. I will pull the bulb when I go to do the circut board. bc I will take a pic. soon and try to figure out with the help of my wife (computer wizard) how to post a pic.
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03-19-2004, 09:15 PM
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Oh, and Randy you are right about the current draw. I read about the Volvo (700 and 900 series) not being a good car to use these on (My wife has one, 1993 960 Wagon) I tried on my Mercedes (1992 300 te 4-matic) and the same thing. So I moved on to the Porsche. I figured that with a car that is 22 years old it would not matter with the central warning system. Goes to show you that Porsche was at least 10 years ahead of the comp.
03-19-2004, 11:43 PM
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Definitely post a pic when you can, as I too was thinking of doing this. (I was just too poor to be the guinea pig, and was waiting for someone else to do it.) TIA,
03-20-2004, 01:27 AM
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Chucker,
If you are electrically inclined, adding (another) resistor in each affected circuit should do the trick. Though the Central Informer brain was cutting edge, the actual tech involved is rather basic - ergo, it is just looking for the 'required' current draw, then it determines all is well.
1/4 or 1/2 watt carbon resistor. Don't know how many ohm you would need, but you can calculate if you count the LEDs and then multiply for their individual draw, don't forget to include the already built-in resistor (LEDs need a resistor in the circuit to keep from blowing). Then just calculate the current draw of a stock bulb - the owner's manual in the glovebox will tell you the wattage of the bulb.
You can find the required formulae in any 'home electrician' kinda book, about $6 at Home Depot. Or google has a neato calculator function.
HTH,
Greg
If you are electrically inclined, adding (another) resistor in each affected circuit should do the trick. Though the Central Informer brain was cutting edge, the actual tech involved is rather basic - ergo, it is just looking for the 'required' current draw, then it determines all is well.
1/4 or 1/2 watt carbon resistor. Don't know how many ohm you would need, but you can calculate if you count the LEDs and then multiply for their individual draw, don't forget to include the already built-in resistor (LEDs need a resistor in the circuit to keep from blowing). Then just calculate the current draw of a stock bulb - the owner's manual in the glovebox will tell you the wattage of the bulb.
You can find the required formulae in any 'home electrician' kinda book, about $6 at Home Depot. Or google has a neato calculator function.
HTH,
Greg
03-20-2004, 03:26 PM
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Must see pics!
I tried red and orange LED bulbs in a few cars, with no success - they wouldn't flash or sometimes wouldn't fit properly. It was much later that I realized that you needed a resistor for the flasher!
If you don't want to mess with resistors for the tail light brain, you can unplug the two pin connector (over the fuse box) which connects the bulb brain to the dash light.
Or, you can remove the brake light brain and replace it with a jumper:
12 pin connector found on 80's Mercedes (easily found in the U-pull junkyards), I got this one from under the dash, on the passenger side. The pins are soldered so it is easy to rewire these. (Made the incandescent bulbs a bit brighter too?) Note that different years had different brains, so check your wiring diagrams! (This is for 81)
Come to think of it, you could incorporate a resistor in the plug, if you went with turn signal bulbs, and they didn't flash...
Anyone know if our turn signal relay is relay based vs. bi-metal?
I tried red and orange LED bulbs in a few cars, with no success - they wouldn't flash or sometimes wouldn't fit properly. It was much later that I realized that you needed a resistor for the flasher!
If you don't want to mess with resistors for the tail light brain, you can unplug the two pin connector (over the fuse box) which connects the bulb brain to the dash light.
Or, you can remove the brake light brain and replace it with a jumper:
12 pin connector found on 80's Mercedes (easily found in the U-pull junkyards), I got this one from under the dash, on the passenger side. The pins are soldered so it is easy to rewire these. (Made the incandescent bulbs a bit brighter too?) Note that different years had different brains, so check your wiring diagrams! (This is for 81)
Come to think of it, you could incorporate a resistor in the plug, if you went with turn signal bulbs, and they didn't flash...
Anyone know if our turn signal relay is relay based vs. bi-metal?
03-21-2004, 06:27 PM
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I think that this will work. I went out and took a pic of the shark with one LED on the left side and the traditional bulb on the right side. The flash really picked up on the reflectors (sorry). But as I mentioned the light is more focused with the LED bulb.lights
03-21-2004, 11:28 PM
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Big difference!!!!!!!!!!! Looks good. I'm no electrical expert, so I'd need someone to figure out where and what sized resistor to install in my GT. When it comes to 'lectricity, I need idiot proof instructions. (usually, but not always) LOL.
03-22-2004, 04:32 AM
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Chucker,
They do look cool, it creates a round look in the square lens.
Are the LEDs as bright as the incandescent from a distance?
(Rotated, cropped, resized, reflectors dimmed, and blurred)
Can you put one in the turn signal position and see if it blinks?
...
I'm guessing you could achieve a similar look with the regular bulbs, by using a round reflector 'skirt', slipped over the bulb base. bcdavis?
I like the instant-on of the LED bulbs, though. Ideally, I would like to have the brake bulbs have a subliminal, micro-second duration, hey-dumbass-I'm-braking-now, hyper-flash, when they are first energized.
They do look cool, it creates a round look in the square lens.
Are the LEDs as bright as the incandescent from a distance?
(Rotated, cropped, resized, reflectors dimmed, and blurred)
Can you put one in the turn signal position and see if it blinks?
...
I'm guessing you could achieve a similar look with the regular bulbs, by using a round reflector 'skirt', slipped over the bulb base. bcdavis?
I like the instant-on of the LED bulbs, though. Ideally, I would like to have the brake bulbs have a subliminal, micro-second duration, hey-dumbass-I'm-braking-now, hyper-flash, when they are first energized.