# Rear parking lights not working, no error code, help!



## degraffb (Jan 30, 2011)

Hey guys,

I recently did a halogen to xenon+led headlight swap. Wired everything in this past friday and played around with the coding until I got the lights working. Just tonight I just noticed that the rear parking lights/tail lights weren't working at all. With the light switch all the way to the on position I get: LED DRLs on, Xenons on, all interior and dash lights on, rear license plate lights on, brake lights function correctly, signal lights function correctly. My first thought was fuse issue...but I don't know which one to look for because I couldn't locate it in the manual. Other thought I have, could this be vagcom coding problem?


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## VWAddict (Jun 12, 1999)

Absolutely it COULD be Vag-Com... but there are too many possibilities to guess at, if you recoded.

Hopefully you stored/noted the 'before' settings?

Go look at the long coding and see what it tells you about how it's set, start from there. -Worst comes to worst, plug the old stuff back in and go back to the old coding to either prove or eliminate a fuse issue or similar.


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## degraffb (Jan 30, 2011)

Well good thing I copied and pasted the original long code to a text file. I'll go back to that and see what happens. Does anyone know which fuse is for the tail lights just incase?


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## mike3141 (Feb 16, 1999)

Vag-Com keeps a log file of the before/after values in a Log directory when you make changes.


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## VWAddict (Jun 12, 1999)

degraffb said:


> Does anyone know which fuse is for the tail lights just incase?


Take a look at your fuse cover... I don't have a photo of the top few lines in the list:


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## mike3141 (Feb 16, 1999)

If some of your tail lights are working and others aren't then it isn't a fuse....they should all be on the same fuse. More than likely their power source is the electrical controller which probably has its own separate fuse.


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## degraffb (Jan 30, 2011)

Well I looked for the tail light fuse everywhere and can't find it. Also, I coded back to the orignal code before I made any changes and no luck. I think I need to be a little more specific about what's not working. On the face lift models (like mine) there is a led strip in the rear housings that lights up as the tail lights. That is what I cannot get to turn on. Still no error code and using the VCDS it read the tail light circuit as being 100%??? I'm so confused...Also both sides are out and I assume it happened at the same time.


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## degraffb (Jan 30, 2011)

mike3141 said:


> If some of your tail lights are working and others aren't then it isn't a fuse....they should all be on the same fuse. More than likely their power source is the electrical controller which probably has its own separate fuse.


when you say electrical controller are you talking about the CEM under the dash? Because I looking at the CEM schematics, Plug B pin 10 and Plug C pin 10 are locations for "Side light rear right/left" I don't know if I'm on the right track here...


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## mike3141 (Feb 16, 1999)

Yes--the Central Electric(al) Module....

AFAIK all lighting is controlled from there and I would think that external lighting (except HID power) is sourced there.

"Side light rear" sounds like the outboard tail lights.....I do remember that the ETKA descriptions for the different configurations of the light switch referred to "side lights".


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## degraffb (Jan 30, 2011)

mike3141 said:


> Yes--the Central Electric(al) Module....
> 
> AFAIK all lighting is controlled from there and I would think that external lighting (except HID power) is sourced there.
> 
> "Side light rear" sounds like the outboard tail lights.....I do remember that the ETKA descriptions for the different configurations of the light switch referred to "side lights".


Okay, well when I get a chance tonight, I will get underneath my dash and make sure that those locations are seated correctly. God I hope this works because I'm guessing my only other option after this is to make a warranty claim with the stealer.:banghead:

Thanks for helping me out with this mike!


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## VWAddict (Jun 12, 1999)

'side lights' is English (UK) terminology for the 5-Watt incandescent (or equivalent) tail lights (not the 21-Watt "bright" kind used for brake or turn signals) when referrin to rear side lights, and at the front of the car, 'side lights' means corner markers, or any low-power (again, typically a 5-Watt bulb) light which is used as a parking light.

Basically, 'side lights' are the lights -white at the front, red at the rear) which are illuminated whenever the headlights are switched on, and left on as 'parking' lights. Low-wattage.


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## degraffb (Jan 30, 2011)

VWAddict said:


> 'side lights' is English (UK) terminology for the 5-Watt incandescent (or equivalent) tail lights (not the 21-Watt "bright" kind used for brake or turn signals) when referrin to rear side lights, and at the front of the car, 'side lights' means corner markers, or any low-power (again, typically a 5-Watt bulb) light which is used as a parking light.
> 
> Basically, 'side lights' are the lights -white at the front, red at the rear) which are illuminated whenever the headlights are switched on, and left on as 'parking' lights. Low-wattage.[/QUOTE
> 
> Perfect, thanks for the explanation and I'm sorry about being such a noob with this. Hopefully it's just a loose connection on the CEM!!


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## degraffb (Jan 30, 2011)

Okay, I got a chance to look at the CEM plugs and pins and everything was snug and in the right location. I don't know what to make of this...any ideas?


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## degraffb (Jan 30, 2011)

Here's something I just thought about. When I wired in the Kufatec harness into the CEM I had to remove two pins that where already in place. They were at locations Plug A, pin 7 and Plug D, pin 10. On the CEM schematic those locations are labeled "side lights front left/right" Now my LED DRLs on the headlight work correctly when wired into the but should I plug those two pins I removed into the "side light rear" locations on plug B and C?


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## mike3141 (Feb 16, 1999)

Can't hurt to try?


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## VWAddict (Jun 12, 1999)

But if you had 'cold sensing active', it would know that the circuit was open, I'd have expected...

Try it none the less, I suppose.


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## degraffb (Jan 30, 2011)

Okay, a little update to this. So on the 2009 A3 using the kufatec harness for the Bi-xenon retro you need to remove two pins/wires in order to wire in the LED DRLs. Well I figured out that those two original wires are for the LED tail lights...ugh.

So now that I know it's not a coding issue, would anyone know where I need to wire the LED tail lights so they functions correctly? is this something I should splice the DRL and rear tail lights wires together? Any help will be much appreciated.


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## VWAddict (Jun 12, 1999)

Wait... explain a bit for me if you would...

You removed two pins which USED to feed the rear LED tails and used them to feed the front LEDs instead? or am I reading you wrongly?

If so, then yes, that's why the rear tails don't work. -Obviously, BOTH would have to be wired, and -assuming that you want them on together- they should be wired together.

Knowing which was hot (switched +12V) and which was cold (ground/0V) is all you need to know... after that just splice them together and you should be good.


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## degraffb (Jan 30, 2011)

VWAddict said:


> Wait... explain a bit for me if you would...
> 
> You removed two pins which USED to feed the rear LED tails and used them to feed the front LEDs instead? or am I reading you wrongly?
> 
> ...


Yes, let me fully explain how I had install the Kufatec harness. So the harness allows me to go from a 10-pin plug for the the halogen headlight housings from factory to the required 14-pin plug that the OEM xenons use. On top of that, there is a total of 4 wires coming from the kufatec harness that give function of the shutter (for xenon hi beams) and the LED DRLs. Two of these four wires thus are wired into the CEM for the control of the shutter in the xenon housing as hi beams. Those shutter controlling wires needed to be wired into Plug A pin 5 and Plug D pin6, these two locations did not have a preexisting wire. The other two wires of the kufatec harness are the power source for the front LED DRLs, one wire to power each side. They are required to be wired into the CEM at locations Plug A pin 7 and Plug D pin 10. These locations had preexisting wires and those wires obviously the wires that control the rear LEDs.

So I am thinking what you are, I could either solder the wires together so they share those locations or there may be an empty pin location that becomes active for the rear LEDs after the recoding?


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## bmw511 (Jul 16, 2010)

Sounds like you just need to mate the pre-exiting wires to the new wires and you'll be done.


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## VWAddict (Jun 12, 1999)

+1.


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## mike3141 (Feb 16, 1999)

Wouldn't that make the tails come on whenever the DRLs were on?


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## degraffb (Jan 30, 2011)

That's I thought...So I'd have to live with tail lights on whenever I had my DRLs on?


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## degraffb (Jan 30, 2011)

Do you guys have any advice on how to mate these wires together. I have never done anything like this before. Do I need a soldering iron?


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## VWAddict (Jun 12, 1999)

Either crimp, or use Insulation-displacement connectors (the Gel-filled kind!) or solder and cover with heat-shrink tubing.

DO NOT use twisted-taped connections, or I will found where you live, hunt you down and gut you like a fish!

(Twisted, taped connections do NOT last, are mechanically unreliable, and corrode. They also come with a death sentence, delivered by ruthless ninjas with ice-water in their veins.)


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## neu318 (Feb 18, 2003)

Do you know anyone that has a facelift A3 that came with the LED headlights already? If so, check the wiring on theirs. I find it weird that you have to wire them to where the rear LEDs plug in.


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## degraffb (Jan 30, 2011)

neu318 said:


> Do you know anyone that has a facelift A3 that came with the LED headlights already? If so, check the wiring on theirs. I find it weird that you have to wire them to where the rear LEDs plug in.


Yeah it does seem totally weird that I need to go through all of this but it could be due to the revision of CEM that came in my A3. Well tonight instead of going through a whole soldering event I located the pins for one of three rear brake lights and used vcds to make that light a tail light that powers the rear LEDs. Now everything working correctly...Unfortunately I currently don't know anyone here in the Portland area that has a face-lifted A3 with the LED DRLs.


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## DublAron (Nov 27, 2021)

degraffb said:


> Well I looked for the tail light fuse everywhere and can't find it. Also, I coded back to the orignal code before I made any changes and no luck. I think I need to be a little more specific about what's not working. On the face lift models (like mine) there is a led strip in the rear housings that lights up as the tail lights. That is what I cannot get to turn on. Still no error code and using the VCDS it read the tail light circuit as being 100%??? I'm so confused...Also both sides are out and I assume it happened at the same time.


Literally same thing happened to me. Bought new lights and everything put them in and still nothing, did u ever find out what the issue was and how to fix it??


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