DIY: Error-Free Rear License Plate LED Lights the Easy Way for B7 A4

[wildcat333]

DIY: Error-Free Rear License Plate LED Lights the Easy Way for B7 A4

Parts and Tools needed:
- 2 new LED bulbs. I purchased mine as part of a complete LED light kit from Krauto Parts c/o Emil: http://www.krautoparts.com/ Great service all around. 36 mm festoon LEDs are what you need: http://www.krautoled.com/products/36...led-bulbs-pair
- 2 Ohmite brand wire-wound resistors (50 Ohm, 5 Watt). I purchased mine on eBay from seller "r_francis82". The resistors cost me about $6.00 shipped.
- Tiny phillips screwdriver (glasses repair kit size).
- Thin flathead/regular screwdriver; or thin file.
- A normal size screwdriver (any size).
- Pliers (any size).
- Microfiber towel or cloth.

Difficulty:
- 1 of 10. This install took me MAYBE 15-20 minutes.
- This was one of the easiest mods that I have done to date - mostly thanks to the idea and info from Audizine member, Schweini - thanks again!
- See where this idea started from if interested: http://www.audizine.com/forum/showth...-today/page236

How-to guide with pics:

- Remove your license plate with screwdriver to create more room and easier access to the plate light housings.

This is what it looks like the light housing is still installed:


- Take your tiny screwdriver, and remove the one screw from the light housing. The light housing probably will stay put (and not fall out), especially if it has never been removed in its lifetime. Mine took a look coercing from a very thin flat screwdriver. A very thin file would also work if needed.

This is what it looks like when removed:


This is what the OEM bulb looks like:


- Remove the OEM bulb gently. Do not break any of the metal pieces in the housing.

Light housing with OEM bulb removed:


- Use microfiber towel or cloth to clean the light housing at this point (inside and out). Might as well.

- Get your LED lights ready to install.

LED lights:


- Install LED light into housing. It will fit in the metal clip in the exact same way as the OEM bulb.

LED light installed in light housing:


- Feel free to angle the LED light however you feel. I angled mine about 40 degrees pointed towards the car. I was trying to achieve the look of having the LED light mostly on the license plate, and not on the bumper or ground behind my car.

- Take the resistor and get ready to wrap the metal wire contacts around the light housing prongs. The wire is a little too difficult to manipulate with just your fingers. I figured out the length that I needed, and put a normal-sized screwdriver against the metal wire contacts, and wrapped the metal wire contacts around it, creating a circle. I then took the pliers and crimped the metal wire contact circle into almost an oval shape. I then slipped these oval shapes over the lighting housing prongs. If needed, gently use pliers and make sure the contacts are touching the resistor metal wire contacts nicely.

Pics of this process:








- Add heat shrink around the resistor if you want. This just makes sure that the small amount of heat from the resistor does not damage the LED lights or the plastic light housing.

Pics of heat shrink:






- Install your new LED housing with resistor back into the trunk lid. I installed each side without putting the screw in at first, just in case. Started the car, and turned on headlights. Made sure the LED light angle was how I wanted it. Kept the car running (again just in case). Put the screw back in. Confirm you are not getting any bulb-out warnings. Repeat for the other side.

OEM (left) versus LED (right):


Both LED plate lights installed:


The benefit of doing it this way versus the other method is that you do not need to remove the trunk clip or find a spot to mount the resistors like in that method. I have been assured that these resistors do not get hot, therefore the housings and lights should not be in danger.

Grab the LED lights and resistors, and do this on your lunch break or after work some day. It was really simple, and I am happy so far. Note that I installed these during the day, so I do not yet have pics of the plate lights at night yet. I will update this DIY thread soon with night pics. Hopefully I angled them properly the way I wanted. The good news is that if they need adjusting, it will only take me approx. 5-10 minutes to do so now.

Good luck, and ask any questions that you have here in this thread. I will be sure to answer any questions that I can, and I'm sure Schweini will be happy to help out as well!


Edit:

I have a RED DISPLAY.

[wildcat333]

Night pics added:






Night video added: be sure to watch in full HD 1080p!




I feel that the first photo shows the true color and brightness of the plate lights the best. They definitely are NOT as bright as they seem in either the photos or the video. I guess it is difficult to capture the true brightness and light quality at night. Looks good though to me.

[blownb6]

Thanks for write up , my bulbs just died wanted to do this mod but did not want the error ,

[A410]

Very nice!!! Will have to get on this soon! What was the approx total cost??? Maybe add that to the description, just as a quick reference too

Again, nice job! I like it.

[dbens]

damn i just spent like 2 hours a month ago wiring in resistors per Phil's DIY. o well ! Nice writeup though, you think something similar would work for the DRL LED's?

[fly300kts]

Sir, your resistor is going to melt the crap of everything around it
5W is way to small for the difference of draw. For info, a 25W gets hot so imagine a 5W

Phil

[wildcat333]

What was the approx total cost???

Good idea-
I just edited my original post:

"I am in the process of confirming the exact mm size of the festoon bulb from Emil, and will post back soon. I will also post a direct link to the bulb once confirmed."

"I purchased mine on eBay from seller "r_francis82". The resistors cost me about $6.00 shipped."

damn i just spent like 2 hours a month ago wiring in resistors per Phil's DIY. o well ! Nice writeup though, you think something similar would work for the DRL LED's?

I don't believe these will work on the DRL bulbs. I don't know the technical reason for this, but I think it requires more volts/watts/something. Someone else will be able to say, but proper resistors are needed for DRL's. Let me know if you have questions about them, since I have done LED DRL's.

[wildcat333]

Sir, your resistor is going to melt the crap of everything around it
5W is way to small for the difference of draw. For info, a 25W gets hot so imagine a 5W
Phil

Hi Phil,
I certainly hope not. Schweini has been testing these for some time now. I will wait for his reply, because I don't know the technical electrical info to reply to your post.

[fly300kts]

Hi Phil,
I certainly hope not. Schweini has been testing these for some time now. I will wait for his reply, because I don't know the technical electrical info to reply to your post.

Since the access it pretty easy do this test :
Pull your assembly off and connect one side to the positive side of your battery and the other side to the negative side, using 2 wires.
After 30 secs, touch carefully the resistor

Phil

[{PMS}fishy]

I'm with Phil, you really need at least an 8ohm 20w resistor when ever replacing an incandescent bulb with an LED.

[gelgel]

Thanks for the write-up. Do you have color display?

I tried sth similar few months ago..
http://www.audizine.com/forum/showth...plate-resistor
the resistor that I am using is http://www.ebay.com/itm/230719186583...84.m1497.l2649
and I had one resistor for each bulb. But I am still getting the bulb out error..
any insight?

[wildcat333]

I have RED DISPLAY.


Sent from my iPhone via Tapatalk.

[Schweini]

The circuit for the license plate resistors draw roughly 4w, these resistors are good for 5w, you're not going to melt anything at all. 4w is not nearly enough to be melting the plastic, and if anyone is worried with this mod, then go buy some heatshrink for $2 from a hardware store and apply it around the resistor

This setup Wildcat has DIY'd has been my setup for nearly a year and I don't even have any heatshrink on my resistors. Everything is fine

[Schweini]

Thanks for the write-up. Do you have color display?

I tried sth similar few months ago..
http://www.audizine.com/forum/showth...plate-resistor
the resistor that I am using is http://www.ebay.com/itm/230719186583...84.m1497.l2649
and I had one resistor for each bulb. But I am still getting the bulb out error..
any insight?

You're using the wrong resistors my friend. 100 ohms is way too high. Get a 35-50ohm resistor. The circuit asks for a specific ampere, with that 100 ohm in there you're bringing the amps WAY too low.

[KOT]

really nice description and pics. will do to my audi same thing. thanks

[gelgel]

You're using the wrong resistors my friend. 100 ohms is way too high. Get a 35-50ohm resistor. The circuit asks for a specific ampere, with that 100 ohm in there you're bringing the amps WAY too low.

thanks for the pointer! Will give this a second try. I'll get the resistors that Wildcat is using. Hopefully this will work on color display too.

[doublezero30]

nice writeup mike! lights look good! if i didnt just buy the ECS LED plate lights i would be doing this. picked them up for $45 shipped - the best price ive seen them at. plug and play, no error on red display.....baaa-zing! but both options are good ones! my LED bulbs burnt our fairly quickly though.

[B7Joe]

Great DIY. Some more specifics on the exact resistors (link to ebay item maybe) and specs on the bulb (looks like you're working on that) would be great. Looks like the bulbs are the CANBUS type sold on that website, just by looking at the heat sinks, but could be wrong. There are so many variations out there, that that would be very helpful.

Nice job! Thanks

[Khaotic]

Seems your LED's also have resistors in them?
Atleast in my experience, LED's wont have a heatsink on them if they do not already have some sort of resistor built in, since there would be no need to heatsink LED's otherwise.

I tried with 5W resistors when I did this long ago, and mine also got to hot to even hold for a second and perhaps it wouldnt melt plastic but I wasnt comfortable having something that hot inside my trunklid with practicly no ventilation on a varm summersday. Also, I did wire mine further inside the trunklid so there were more wires etc that were in the riskzone of the heat, so swapped them for 50W which barely gets warm at all.

Otherwise, nice DIY and people should definitly go for this "right" way to do it!

[jonnybravo]

What was the resistance of the 50w resistors you used. And is it necessary to get wirewound resistors?

Seems your LED's also have resistors in them?
Atleast in my experience, LED's wont have a heatsink on them if they do not already have some sort of resistor built in, since there would be no need to heatsink LED's otherwise.

I tried with 5W resistors when I did this long ago, and mine also got to hot to even hold for a second and perhaps it wouldnt melt plastic but I wasnt comfortable having something that hot inside my trunklid with practicly no ventilation on a varm summersday. Also, I did wire mine further inside the trunklid so there were more wires etc that were in the riskzone of the heat, so swapped them for 50W which barely gets warm at all.

Otherwise, nice DIY and people should definitly go for this "right" way to do it!

[fly300kts]

What was the resistance of the 50w resistors you used. And is it necessary to get wirewound resistors?

It all depends of the LED that you are installing. Yes, wirewound is necessary and the critical advantage, they can be attached to the chassis who will act act heat sink

Phil

[wildcat333]

Thanks to those that liked this DIY.
I will post up night pics tonight.


Sent from my iPhone via Tapatalk.

[event]

Their kit shouldn't error on non color display without modification per THIS THREAD even after 1+ years. Did you confirm this before doing all this?

[FraggyA4]

If anything I would at least solder the resister to the clips and not just wrap them. Otherwise could be a good idea.

[GDC]

after trying several and i mean several different error free bulbs, with negative results. i went with these and never looked back
http://www.ebay.com/itm/AUDI-ULTRA-B...04365c&vxp=mtr
no problems

[Schweini]

Great DIY. Some more specifics on the exact resistors (link to ebay item maybe) and specs on the bulb (looks like you're working on that) would be great. Looks like the bulbs are the CANBUS type sold on that website, just by looking at the heat sinks, but could be wrong. There are so many variations out there, that that would be very helpful.

Nice job! Thanks

These are what I suggested him to get: http://cgi.ebay.com/ws/eBayISAPI.dll...m=261159650482

If you want to know the details about the resistors, it's this: When you replace the OEM bulbs which which have a resistance of 37 Ohms, with LED's, what you're essentially doing is eliminating that 37 Ohm's of resistance. This is because LED's have next to no resistance properties to them. You NEVER consider them a load. Now, because that OEM bulb is not in the equation and LED's have no resistance, you have a straight 12v shooting through the LED's and the ampere rating is almost non-existent. The cars Canbus system reads this, and displays this fault as an error out light display. So what we now have to do, is find a resistor that can match the value of the OEM Bulb to take it's place. a 37 Ohm bulb and a 12v power source gives you an ampere rating of .32 Amps. This is what your car wants to see. So now we need to find a resistor that will produce the same ampere rating when shooting 12v through it. I used the 50 Ohm resistor, so this with 12v will produce an ampere rating of .24 amps.

You're probably saying, well that doesn't match the cars OEM bulb at all??? Well, the LED's have a very minute resistive property, so tacking on a .006 milli-Amp or so will raise the .24A VERY close to the .32A the car wants. This is also why this DIY should be labelled that this will work using THESE specific LED's and THIS specific resistor. Different LED's will have different resistive properties and can but probably wont alter your values. This DIY I came up with was what i found worked best for my application. This will not work for every Audi model

Now when it comes to the Wattage, the 5w as we see on the resistor, that is simply stating how much power that resistor can dissipate. The OEM circuit draws 12V x .32A = 3.84 wattage. This resistor can withstand up to 5w, so in this application, you're good to go.

In a nut shell, the Wattage should never be smaller than the OEM Wattage (3.84w) and anything bigger than that number is good. The larger the better, which is why Phil used much larger resistors. The only reason I used the small ones was because they are much cheaper, and the install takes 5 minutes. The larger the wattage rating, the larger the resistor is going to be! That's why Phils resistor is huge.

If anything I would at least solder the resister to the clips and not just wrap them. Otherwise could be a good idea.

Completely unnecessary, and I highly suggest all of you don't do this. Because the resistors have a small power rating, they will in time eventually ware out and you more than likely will need to replace them. This can be years from now, who knows. If you solder them in there, you'll be sorry. Wrapping them a few times and crimping with some pliers makes adequate enough contact.

[Schweini]

after trying several and i mean several different error free bulbs, with negative results. i went with these and never looked back
http://www.ebay.com/itm/AUDI-ULTRA-B...04365c&vxp=mtr
no problems

I've also tried several too, and I found they ALL eventually break. The third party vendors have no idea what kind of resistor you need in our cars circuitry. Unless they solely designate their LED error frees for the A4 B7, they are just ball parking it. The resistors they throw in may just be cutting it, and once you get some voltage fluctuating due from a dying battery or decaying resistor, you're Error Display will be popping up

[mnuttall]

Sir, your resistor is going to melt the crap of everything around it
5W is way to small for the difference of draw. For info, a 25W gets hot so imagine a 5W

Phil

Two questions:
1) Assuming the resistances are the same why would a 5W resistor get any hotter than a 25W resister? The power being dissipated will be exactly the same.
2) A light bulb is effectively a wire-wound resistive heat source that happens to emit some light. Assuming the light output is the same and the resistance of the resistor is the same as the original bulb the total heat emitted should be the same as the bulb. Why would this damage anything that bulb doesn't damage already?

I'm a mechanical engineer with only limited electrical knowledge so maybe I'm missing something obvious. I also can't view the images from work so there could be something obvious there that would answer these questions.

[Schweini]

Two questions:
1) Assuming the resistances are the same why would a 5W resistor get any hotter than a 25W resister? The power being dissipated will be exactly the same.
2) A light bulb is effectively a wire-wound resistive heat source that happens to emit some light. Assuming the light output is the same and the resistance of the resistor is the same as the original bulb the total heat emitted should be the same as the bulb. Why would this damage anything that bulb doesn't damage already?

I'm a mechanical engineer with only limited electrical knowledge so maybe I'm missing something obvious. I also can't view the images from work so there could be something obvious there that would answer these questions.

It doesn't. I've been trying to tell people this but they all want to believe Phil because he's well known.

Don't get me wrong Phil, your DIY is beautiful and well done, it's just over the top for someone like me who already knows the facts and figures.

[fly300kts]

It doesn't. I've been trying to tell people this but they all want to believe Phil because he's well known.

Don't get me wrong Phil, your DIY is beautiful and well done, it's just over the top for someone like me who already knows the facts and figures.

No hard feeling Man,all good and after all it's your car.

Phil

[Schweini]

No hard feeling Man,all good and after all it's your car.

Phil

exactly, I took a shortcut, where as you did the more professional way of doing it is all

[FraggyA4]

Completely unnecessary, and I highly suggest all of you don't do this. Because the resistors have a small power rating, they will in time eventually ware out and you more than likely will need to replace them. This can be years from now, who knows. If you solder them in there, you'll be sorry. Wrapping them a few times and crimping with some pliers makes adequate enough contact.

You can easily remove solder using your soldering iron.

[Schweini]

Yes I'm aware, it still doesn't deem soldering necessary

if people need a DIY on how to put a resistor on the 2 prongs, they more than likely don't have a soldering iron

[wildcat333]

nice writeup mike! lights look good! if i didnt just buy the ECS LED plate lights i would be doing this. picked them up for $45 shipped - the best price ive seen them at. plug and play, no error on red display.....baaa-zing! but both options are good ones! my LED bulbs burnt our fairly quickly though.

hey nate, which led's burnt out quickly for you? the ecs ones, or different ones?

[Schweini]

hey nate, which led's burnt out quickly for you? the ecs ones, or different ones?

LED's aren't bulbs, so if they burnt out and they were the "Error Free" type and cheap (Ebay) then most likely a soldering came loose and or the resistor they put in place could have broken off


This happened to me with a different set of ebay LED's, I had to solder a piece of metal on just to make proper contact

[wildcat333]

Night time pics to be posted by midnight!

[doublezero30]

hey nate, which led's burnt out quickly for you? the ecs ones, or different ones?

Just the cheap $7 bulbs. I just bought ecs ones to replace them.

[wildcat333]

Added pics and video to post #2 above.

Bought some heat shrink and will add these tomorrow for extra protection. Will post updated pics for the DIY, because at this point, why not.

[drumnjuny]

well done sir.

[Ed Gein]

Car looks great.

I predict HID license plate lights to be the next trend.