How-To: B8.5 Sedan Halogen to LED tail light Swap

[Reciprocity]

Hey everyone, I decided to write up a quick guide on how to code and retrofit B8.5 sedan LED taillights into a halogen equipped car.

This swap is straightforward but is a bit labor intensive since soldering or crimping is required.
The major issue with this swap is that our stock halogen wires are significantly thicker than the LED harness, therefore the pins on the inner taillights cannot be transferred directly into the LED connectors. There are ways around this of course, however the route I chose left the stock wires and pins uncut and unmodified since I like having the option to switch back to halogens.
Another obstacle is the lack of sidemarker wire. Since the outboard LED’s have 5 wires going to them while the stock halogens only have 4. It is possible to lay a wire from the BCM to the sidemarker, it is far more work than I am prepared to do. For anyone adventurous enough I have included the proper coding.

First off, part numbers!
Unless you managed to purchase the taillights with the connectors and pigtails, you will have to buy them separately.
The outboard connector part number is: 4H0 973 713
The inboard (trunk) connector part number is: 8K0 973 754
Wires are not needed for the outboard connectors since the stock pins slip right in.
Inboard are more difficult. I ended up using the stock connector, taking the pigtails from the LED lights and using spade connectors and inserted them into the stock connector. This isn’t a perfect solution however for me it’s adequate, as long as you use proper insulation to prevent a short. The spade connectors that I used have part number 000 979 134 however any narrow spade connector with a width of around 3 mm will work too. You could directly splice the proper connectors onto the stock harness wires, however I did not want to undertake this. I do not have the part numbers for the LED connector pins.

Coding is very simple:
Open VCDS
46-Comfort System
Enter login 16017
Adaptation
Then change every value to what is in the chart.
https://imgur.com/vTiKGhl

PLEASE back up your stock coding! Don’t hold me responsible for entering the wrong value and forgetting the original. I’m just a dude on the internet trying to help any adventurous swappers out and will not take responsibility for any screw ups!

The chart lists channel 201 and 202 as the sidemarkers. For those ambitious enough to haul wires from the connectors to the BCM, use the values included. If not, leave them at the default zero.

I will post the proper pin and wire numbers in the next day or two, still need to take pictures and write down exactly what I did. Generally speaking the pins (except ground of course) can be placed arbitrarily in the connectors, since coding takes care of their function. However tracking down the corresponding channels is a PITA so just follow my wiring!

If anyone has any problems or needs advice feel free to ask!

[Darrenw88]

Hey everyone, I decided to write up a quick guide on how to code and retrofit B8.5 sedan LED taillights into a halogen equipped car.

This swap is straightforward but is a bit labor intensive since soldering or crimping is required.
The major issue with this swap is that our stock halogen wires are significantly thicker than the LED harness, therefore the pins on the inner taillights cannot be transferred directly into the LED connectors. There are ways around this of course, however the route I chose left the stock wires and pins uncut and unmodified since I like having the option to switch back to halogens.
Another obstacle is the lack of sidemarker wire. Since the outboard LED’s have 5 wires going to them while the stock halogens only have 4. It is possible to lay a wire from the BCM to the sidemarker, it is far more work than I am prepared to do. For anyone adventurous enough I have included the proper coding.

First off, part numbers!
Unless you managed to purchase the taillights with the connectors and pigtails, you will have to buy them separately.
The outboard connector part number is: 4H0 973 713
The inboard (trunk) connector part number is: 8K0 973 754
Wires are not needed for the outboard connectors since the stock pins slip right in.
Inboard are more difficult. I ended up using the stock connector, taking the pigtails from the LED lights and using spade connectors and inserted them into the stock connector. This isn’t a perfect solution however for me it’s adequate, as long as you use proper insulation to prevent a short. The spade connectors that I used have part number 000 979 134 however any narrow spade connector with a width of around 3 mm will work too. You could directly splice the proper connectors onto the stock harness wires, however I did not want to undertake this. I do not have the part numbers for the LED connector pins.

Coding is very simple:
Open VCDS
46-Comfort System
Enter login 16017
Adaptation
Then change every value to what is in the chart.
https://imgur.com/vTiKGhl

PLEASE back up your stock coding! Don’t hold me responsible for entering the wrong value and forgetting the original. I’m just a dude on the internet trying to help any adventurous swappers out and will not take responsibility for any screw ups!

The chart lists channel 201 and 202 as the sidemarkers. For those ambitious enough to haul wires from the connectors to the BCM, use the values included. If not, leave them at the default zero.

I will post the proper pin and wire numbers in the next day or two, still need to take pictures and write down exactly what I did. Generally speaking the pins (except ground of course) can be placed arbitrarily in the connectors, since coding takes care of their function. However tracking down the corresponding channels is a PITA so just follow my wiring!

If anyone has any problems or needs advice feel free to ask!

Have you got any pictures of how you did this?

[Reciprocity]

It's been a while since I did this swap, do you need any specific pics? PM me if you need help

[Darrenw88]

Sent u a message there

[Reciprocity]

Haven't received anything yet, just fyi

[Darrenw88]

Ive bought aftermarket led tail lights and left them up to my mechanic to wire them up, he could get everything working apart from the reverse lights, do u know anything about this?

[Darrenw88]

Ive bought aftermarket led tail lights and left them up to my mechanic to wire them up, he could get everything working apart from the reverse lights, do u know anything about this

[Reciprocity]

I don't see why they wouldn't work, as long as the wiring is done correctly. are you getting any errors?

[Darrenw88]

I dont think so, have you any pictures of your wiring by any chance?

[Reciprocity]

I'll have to look for them, it's been a while. euro tails are simpler since they do not have the silly position lights on the side of the outboard tails, plus i added a custom adapter harness so the wire colors are all different.

Did you mechanic do any coding? I'm not too familiar with aftermarket lights but the basics should be the same. If he only rewired then he made a mistake...one wire will still be reverse. I know that FL reverse and pre FL reverse are switched from outboard to inboard, that's where his problem might lie. It's far easier to recode to get them to work than rewiring which is a massive pain.

[Darrenw88]

He never rewired to the car, i gave him the lights an he tested them from an external source to see if everything was working. Do you think if he wired them up and coded them wud it work?

[Reciprocity]

It's difficult to tell to be honest, there are many variables that cannot be controlled for. When you put the car into reverse, do ANY lights turn on? other than brake light of course.

[Darrenw88]

Only the reverse lights come on

[Reciprocity]

wait a few posts before you said that everything worked EXCEPT the reverse lights, now it's the opposite?

[Smac770]

Too little info to guess at.
What is your car? B8.0 or B8.5? 4-door or 5-door? Did it have incandescent or LED stock?
So you bought aftermarket replacement tail lamps. Are they incandescent or LED? Where they made to emulate the B8.0 or B8.5 look? Or do they just got their own look? How many pins are on the outer and inner assemblies?

The right reverse light is always on J393 plug T17o pin 1, with adaptation value 45 on channel 206.
The left reverse light is always on J393 plug T17p pin 14, which is also connected to the rear view mirror if you have the auto-dimming mirror, with adaptation value 13 on channel 205.

So wherever the pins on your tail lamps are for the reverse lights, get them wired back to the correct pins on the J393.
All the other light elements would be on any of the other 14 available J393 tail lamp pins.

(was typing this before the update from reverse wasn't working to only reverse works; still the basic necessary information request stands)

[Darrenw88]

Its a b8.5 4 door, it came with stock halogen lights and i bought aftermarket leds. The car has 3 pins on the outer at the minute and 4 on the inner, the new led lights have 5 on the outer an 5 one the inner

[Darrenw88]

I bought these lights off ebay and the seller told me there was a harness to buy, ive searced everywere for one an cant find it, the only one i can find is for a b8 which is no good

[Reciprocity]

are you sure there are only 3? euro should have 4 just like US. ground, brake/signal, position and reverse.

This is my left outer taillight with stock wiring, only plug is changed to fit B8.5 LED. US models have fifth cable for a small side LED which I did not run.
https://imgur.com/IFPMyKv

This is left inner connector with cut stock B8.5 pigtails spliced into stock wiring.
https://imgur.com/OGn7qxU

You really don't need a harness. I made my own with stock FL connectors and some pigtails I had laying around which can be purchased online for cheap.

[Smac770]

So stock B8.5 4-door ROW (I assume so being Ireland) incandescent.
Your outer left assembly would have had a three wire connector (ground, M6 turn signal, M21 tail/brake) to drive two lighting elements.
Your inner left assembly would have had a four wire connector (ground, M4 tail, M41 parking/fog, M16 reverse) to drive three lighting elements.
Your inner right assembly would have had a four wire connector (ground, M2 tail, M42 parking/fog, M17 reverse) to drive three lighting elements.
Your outer right assembly would have had a three wire connector (ground, M8 turn signal, M22 tail/brake) to drive two lighting elements.

But I can't say what size connector they might have been; could have been a 6-position connector with only three positions used, etc.
My US inner assemblies have only four pins, and the plug only has four wires. But the plug is clearly a 6-position plug, and the spacing on the assembly jack has room for 6 pins.

And you bought B8.5 4-door ROW LED replacements. So these would have:
outer left - five wire
pin 1 - ground
pin 2 - M6 turn --> T17p/9, ch 199
pin 3 - M9 brake --> T17p/6, ch 197
pin 4 - M4 tail --> T32c/31, ch 209
pin 5 - M16 reverse --> T17p/14, ch 205
inner left - five wire
pin 1 - ground
pin 2 - M80 turn 2 --> T17p/11, ch 195
pin 3 - M86 brake 2 --> T17o/9, ch 201
pin 4 - M49 tail 2 --> T17o/12, ch 207
pin 5 - L46 fog --> T17p/5, ch 203
inner right - five wire
pin 1 - ground
pin 2 - M81 turn 2 --> T17o/10, ch 196
pin 3 - M87 brake 2 --> T17p/10, ch 202
pin 4 - M50 tail 2 --> T17p/13, ch 208
pin 5 - L47 fog --> T17o/11, ch 204
outer right - five wire
pin 1 - ground
pin 2 - M8 turn --> T17o/8, ch 200
pin 3 - M10 brake --> T17p/12, ch 198
pin 4 - M2 tail --> T32c/30, ch 210
pin 5 - M17 reverse --> T17o/1, ch 206

So you're at least going to be running two new wires from the J393 to each outer plug, and one new wire to each inner plug. All wires are .35mm^2 or 20awg.
Then wire them up as I've already laid out, pin from assembly to connector/pin on the J393.

And then code appropriately, channels for each J393 output pin already noted.
Though you'll need to look around to build the correct coding value syntax.
You shouldn't need to monkey with channels 205 or 206. These are reverse and are the same no matter anything on a B8 A4.
And of course you won't need to mess with 211 or 212 as these are the license plate lamps and high mount brake light, which you're not modifying.

Not that I know any of these for self proven sure. But based on what I've tried to learn recently, it's what I would try first if I were doing the swap.

[Smac770]

I have a curiosity about the B8.5 4-door ROW LED outer assembly (8K5 945 095 AC).
ETKA seems to imply that there's still one W-16w bulb in it.
When I look at the backside of what one eBay listing claims to be a 8K5 945 095 AC, is that plug with the black/yellow wires on it right behind the green plug actually a bulb holder with a W-16w bulb in it? Is the reverse light still a bulb and not an LED? Keep that in mind when coding the (is bulb (1) or is LED (0)) channel. Internet seems to say it's channel 181, but it's clearly channel 187 and 188 (though that's only for the license plate and high mount brake light) that correctly match on my factory coded car.

[Gunnark100]

When I look at the backside of what one eBay listing claims to be a 8K5 945 095 AC, is that plug with the black/yellow wires on it right behind the green plug actually a bulb holder with a W-16w bulb in it? Is the reverse light still a bulb and not an LED? Keep that in mind when coding the (is bulb (1) or is LED (0)) channel. Internet seems to say it's channel 181

Yes, etka is correct, facelift led rear lights have one "not led" in it and its reverse and yes, 181 is not led vs bulb channel...


Edit: @Smac770 i will pm you answer tomorrow regarding your question below...

[Smac770]

Gunnark, do you know at all why the B8.0 LED retrofit kit from Audi (8K5 098 100 for 4-door, 8K9 098 100 A for 5-door; ROW spec only) has no restrictions for the 4-door kit, but says not for Japan and requires 5D7 (868MHz J393) for the 5-door kit?
Is there some known interference issue with the B8.0 5-door LED lamps and 315MHz or 434MHz operation (for the key fobs and, if '09, TPMS sensors)?
It seems odd that has never been brought up before, that I remember reading.
parts.audiusa.com lists all three J393 (CQ, CT, CS), so it would seem US spec B8.0 had all three MHz under various circumstances. Just nothing documents what dictates that selection, specifically.

[RRHMJ23]

Is this option available for the b8 model ?

[Smac770]

The process should be no different for the B8.0. But you might have different count of wires you need to run, and you might have some plug swapping to do, etc. But in the end, the whole process is the same: get all the pins on the lamp assemblies connected to the pins on the J393 and put the right values into the adaptation channels.

[Redporsche]

Does anybody know the color to function for the tail light wiring? A4 b8 Avant. I have dectane tails and both the lights and the wiring are only 4 wires. I just need to repin the plugs and do coding.

[adamfitz]

I am collecting standard facelift led s line taillights tomorrow to replace my b8.5 halogen tail lights, I am just wondering if this is what I need : led taillights/led outboard/inboard connecters / pin removal tool/ vagcom to code them / spade connectors .

I am wondering if you have the wiring diagram to show me which pins align to which wire please.

thanks very much

[Smac770]

Adam,

The chart I made:

taillamp wiring B8.5 EU 4-door.jpg

[Aa4b85]

Hi, I have a 2014 A4 b8.5 UK saloon which came with halogen tail lights and I recently received the LED tail light units which I plan on installing. This thread has been incredibly helpful especially with the wiring, but I am struggling with the coding. I have access to an OBDEleven for coding but I don’t understand how I can find out what bits I need to change to make the LEDs work. Can anyone help me out?
Thank you.

[Smac770]

Halogen is never a term for the tail lights. That would be incandescent. Halogen bulbs would only be relevant for head lights.

Assuming you are installing B8.5 EU 4-door LED tail lights, then simply copy the coding of channels 181-214 of a B8.5 EU 4-door that came factory with LED tail lights. Assuming you establish the same wiring layout as the factory config would have had. I'm sure someone has posted the factory B8.5 Euro sedan LED coding somewhere. Though, that's the one, out of 4 variations, of B8.x Euro LED coding that I do not have a sample of.