B8.5 custom tail light diary

[2by2handsofblue]

one option for the a/s/rs5 is purchasing a set of euro tails and sending them to https://audi-retrofits.co.uk/. not sure of the price but expect it to be easily over $1k.

That's an option but a no go lol.
Maybe I'll set up a go fund me account for my issues

we are the borg! resistance is futile.

[Drunktank]

OK, my New Year's resolution is to get this project done early this year, so let's go.

Got the other light's boards soldered and connected up to another controller. Synced up the controllers and made some animations.


First pass turn signal





Startup sequence (ignition on), followed by shutdown (ignition off) which is just reverse of startup.




Next up I need to take a set of factory lights and power up each wire and see what functions the wires correspond to.

[B4Audi]

Nice! Will you be selling any?

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[Drunktank]

It's possible, but they'll be expensive. We don't have any cheaper aftermarket lights to use as donors, so you're at $1k for a used factory set before any work has been done.

[B4Audi]

What if the customer provides their own lights?

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[Drunktank]

I don't want to get too much in the weeds on that, but it's possible. Have a ways to go to establish this as a proven product.

[btb.tyler09]

OK, my New Year's resolution is to get this project done early this year, so let's go.

Got the other light's boards soldered and connected up to another controller. Synced up the controllers and made some animations.

First pass turn signal





Startup sequence (ignition on), followed by shutdown (ignition off) which is just reverse of startup.




Next up I need to take a set of factory lights and power up each wire and see what functions the wires correspond to.

So you've made them individually addressable?

You'll probably do this yourself anyway, but i did map the wiring for the Left tail lamp at one point, so I figured I'd post it for you.

inside Tail Lamp -- Signal -- Car harness Connection # and color
Red -- GND? -- #3 Gray/Yellow
White -- TS/Brake -- #2 Green
Yellow -- Running Light -- #4 Gray/Black
Black -- GND -- #1 Brown
Green -- Reverse Light -- #5 Black


I have the plug on the inner light mapped too, but i don't think you need it. I have attached the wiring diagram from the manual for reference. You should be able to trace the wires back to the 17 pin connector and add that Blue wire used in the EU for a turn signal. You would have to program that change into the BCM to separate the Turn signal and brake signal. That's what i plan to do if i ever get back to this. How do you plan on programming the shutdown procedure? I guess you can add a line that's always hot and wait for the running light signal to go off?

Great work and i look forward to seeing your project finished. Maybe it'll finally motivate me to finish the PCB design for the switchback DRL and then do my own tail lights.

B8 tail light wiring.PNG

[Drunktank]

Thanks Tyler, that definitely helps. I can use those to then trace the wires on the secondary harness that's on the light housing itself, cut the secondary harness brake wire (so I'm not cutting the main harness) and measure the current so I can figure out which load resistors to get to fool the system.

I'm not actually going to recode anything. The plan is to use the 3rd brake light and front side marker for separate brake/turn triggers. For shutdown sequence, it will use the same wire as startup sequence. If ignition wire goes from high(voltage) to low(no voltage), then run shutdown sequence with no repeat.

[2by2handsofblue]

Ok keep us updated if u plan on selling this.
I would buy a set of lights and send them to u.
Would this work for a b8.5 s5 rear lights?
I know the shape of the lights are different compared to the s4

we are the borg! resistance is futile.

[Drunktank]

Maybe I'm reading it wrong, but my lights didn't match the above diagram. Some wires were correct, but some weren't. My left, inner light wires are brown(ground), blue/black(brakes), red/black(running lights), and grey/yellow(fog lights). This matches the wiring diagram I have from Mitchell1.




I had no idea what my rear fogs were, but apparently it's just a portion of your brake lights.



This option will have to go, as it's not worth programming in the interactivity and priority between rear fogs and brake, and I never use them anyway.

Anyway, looks like brake lights only draw .24A. This will be a nice small load resistor, as we're already dealing with LED's so the power difference is much smaller than going from incandescent to LED.

[Ashtonts]

I don't want to get too much in the weeds on that, but it's possible. Have a ways to go to establish this as a proven product.

FWIW I’d be in for a set as well if you ever decide to market these. Very cool project for sure!

[B4Audi]

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