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Discussion Starter #1
Hi everyone. Like many of you, I was frustrated about the few non-functioning LED bulbs in my stock LED tail lights on my 04 325Ci. And as a bit of an electronics geek, I decided to take up the challenge before I spent hundreds on a replacement assembly. I was successful and it is easy to do for about $2 per bulb.

This DIY requires very little technical expertise and the only tools you need are those to remove the tailight assembly, a soldering iron, an Xacto or razor blade, wire snips, rosin flux for soldering electronics and a bit of solder. Plan on a couple hours because the work can be slow.

I tried to post pics but it may not work and I am not a computer expert so who knows if it will work. Also, I apologize for the pic quality if they suck, and also for how crappy my work looks. I was experimenting with low expectations of success so I didn't really take my normal care.

Step 1: Go to RadioShack and buy the correct number of LED bulbs as shown in the last pic. If you can't find exactly that one, a 3mm with the same specs will be fine. The critical things are the voltage (don't get anything needing 3V or more) and the diameter because you want it to fit back into the reflector. I am not sure you want anything much brighter or dimmer as this one since the end result you are looking for is to match the originals.

Step 2: With the tail light in place and plugged in, turn on the headlinghts to identify the offending bulbs. Make sure you have a way of knowing which are dead once you disassemble things. Most likely, the line across the bottom will be dead, along with some others. When the assembly leaks water into it, the water collects inside the housing which over time destroys the little LEDs and damages the board itself.

Step 3: Remove the tail light and CAREFULLY disassemble until you get the circuit boards ceompletely removed from all parts of the housing and lens (first pic). Make sure you keep the circuit board oriented correctly so that you replace the correct bulbs.

Step 4: If you aren't already familiar with LEDs, the very small white cubes are the LED bulbs (second pic). Look along the bottom row for signs of water damage and corrosion. The bulbs are most likely dead where you see that damage. These work like old fashioned Christmas lights so that when one dies on a "string", the rest go out too. Even if you have other bulbs that are dead, replacing the ones on lower row will probably fix those lined up above it. Where you see corrosion/damage, pop the old LED off by inserting a small screwdriver or Xacto blade under it. It takes only a little bit of force. Throw that bulb away. Do this for all the damaged bulbs ONLY.

Step 5: Where the bulbs were mounted, there are patches that are lighter green than the "background" of the board. These are the traces - essentially flat wiring bonded to and covered up by the green PCB material. Using an xacto, razor blade (or a dremel with a midl abrasive wheel), scrape away a bit of the light green material to expose the copper underneath it (third pic). STOP WHEN YOU SEE CLEAN COPPER - DO NOT SCRAPE TOO MUCH. Try to get as much of the green off because solder doesn't stick to it.

Step 6: Again, if you aren't familiar with LEDs, they are "directional", meaning they only work if mounted in the correct orientation relative to the electricity flow. You don't need to be too technical for this, though. Go back to the car and plug in the circuit board. Turn the headlight on to illuminate the lights. Take one of the LEDs out of the package and touch one lead to one patch of exposed copper, doing the same with the other lead and copper patch. If nothing happens, turn the bulb 180 degrees. When you get the orientation correct, the LED you are holding should light up along with others lined up above it. Make note of which lead goes to which copper patch. I bend the lead upwards for the one that goes to the upper patch and bend the other down to indicate that goes to the lower patch.

Step 7: Heat up your soldering iron, use a bit of solder flux on the exposed copper patches and lay down a small pad of solder on each. Making sure you keep the bulb oriented correctly, bend the leads flat against the bottom of the LED bulb and place the bulb in as close to the same center as the original. Bend one lead to the solder pad, put your soldering iron to it and solder it down. Do the same with the other lead. You make need to add a bit more solder depending on how big the original solder pad was. See the fourth pic.

Step 8: Take the circuit board to the car, plug it in and test it by turning on the headlights and pushing the brake pedal. The new bulb should like up exactly like the others, and all other existing bulbs on the same circuit should as well.

Step 8: If everything works correctly, carefully snip the excess lead wire from the bulb and move to the next one. If it doesn't work, then you may have accidentally soldered the leads backwards, or there may be a short from excess solder bridging the copper patches or perhaps the position of the bulb itself made one lead bridge the traces. Desolder the bulb, make sure there is green space completely separating the two copper patches and resolder the bulb in the other direction, making sure that each lead only touches one copper patch.
 

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Discussion Starter #4
Sure - you can get them at Mouser, DigiKey, Avnet, Arrow, etc. But if you are just ordering these, it would be a small order and shipping would probably be disproportional. On the other hand, if that really is your only option, no big deal.
 

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Because Race...Convertible?
Turbo ZHP Convertible
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Discussion Starter #6
CarbonZHP - those should be fine. I am not familiar with the blinker circuit so there could be something wonky, but most likely not.
 

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Because Race...Convertible?
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I know that they do not depend on eachother since only one is out. My biggest question may be opening the light. I was unable to last time I tried
 

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bought a used OE set as a replacement..my issue is when i turn right the lights do a hazzard instead then i get an error in my dash.

is this fixable? all LEDs are working.
 

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Discussion Starter #9
Mikeetastic - Ugh. Thise are probably not salvagable. Although there is no way for me to know for certain, it sounds like you have fatal circuit damage, like the controller chip. It could be a bad voltage regulator or a broken trace, but the level of effort it would take to tech it out would be significant. Sorry for the bad news.
 
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