# The "K" Wire and OBDII Scanning problems with aftermarket HU install (mk4)



## VR (Jul 2, 2001)

I had a Blaupunkt CD player installed and now my obdII port will not let my scangauge connect to it since the install. I received some info that I just need to disconnect the K wire (yellow) which is switched power? Does this sound right to any of you experts. I also have no AM reception which I would guess is related to my attenna adapter?

if anyone can help you rock http://****************.com/smile/emthup.gif


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## afinley (Dec 29, 2004)

*Re: The "K" Wire and OBDII Scanning problems with aftermarket HU install (VR)*

the k wire is blue and white.


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## sanyi (Jun 21, 2007)

*Re: The "K" Wire and OBDII Scanning problems with aftermarket HU install (afinley)*

Careful i just had the same problem ....i have a 99 Passat Wagon , and i have the wiring diagram from the radio and the "K'- wire is a green/brown wire but check out this link and this will help you identify the k-wire ...
http://www.ross-tech.com/vag-c....html


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## kwalton (Sep 3, 2001)

*Re: The "K" Wire and OBDII Scanning problems with aftermarket HU install (VR)*

if your was built pre 2002.5 and uses the old harness there are known problems with being able to scan the car using the obd2 port. essentially the k-wire travels in and out of the factory radio and when you replace the radio with an aftermarket one the k-line is broken. installing the factory radio whenever you need to scan the car may be the only option unless someone has come up with a bypass.


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## flotsam (Oct 9, 2009)

I know this is an old thread, but just wanted to mention I ran into this no scan problem on a 2002 Jetta. I had put in an aftermarket Kenwood stereo and then the scan wouldn't work. 

Note that i did NOT reconnect the old radio, but with the new aftermarket one removed the scan worked fine.


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## BoostedGLS0218 (Dec 10, 2011)

Ross-tech has a solution on their website the link in another post here. 

From what I understand you'll simply need to remove the wire from x pin in y factory harness. And then of course tape off the exposed wire. 

I haven't tried this myself with my aftermarket hu. But maybe one day ill scan my car and see what happens after I try it. Right now I'm not using my vag-com since my car has been running perfect for a while now


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## AudiMick (Sep 1, 2010)

BoostedGLS0218 said:


> Ross-tech has a solution on their website the link in another post here.
> 
> From what I understand you'll simply need to remove the wire from x pin in y factory harness. And then of course tape off the exposed wire.
> 
> I haven't tried this myself with my aftermarket hu. But maybe one day ill scan my car and see what happens after I try it. Right now I'm not using my vag-com since my car has been running perfect for a while now


Actually you just need to remove the wire running to pin 3 Plug III from the aftermarket harness, leave the Factory wiring alone just in case you ever re-install the original stereo.


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## BoostedGLS0218 (Dec 10, 2011)

AudiMick said:


> Actually you just need to remove the wire running to pin 3 Plug III from the aftermarket harness, leave the Factory wiring alone just in case you ever re-install the original stereo.


I would think that the aftermarket harnesses might be different from each other brand to brand, right?


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## NFrazier (Jul 22, 2006)

If the issue is because the radio was installed and not the other issue, then the radio was installed incorrectly. Plain and simple. ANYONE that knows what they are doing with these cars KNOWS not to hook up the amp turn on/powered antenna wire on those cars.

Just my .02


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## BoostedGLS0218 (Dec 10, 2011)

NFrazier said:


> If the issue is because the radio was installed and not the other issue, then the radio was installed incorrectly. Plain and simple. ANYONE that knows what they are doing with these cars KNOWS not to hook up the amp turn on/powered antenna wire on those cars.
> 
> Just my .02


Who are you referring to in that last sentence there?


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## NFrazier (Jul 22, 2006)

BoostedGLS0218 said:


> Who are you referring to in that last sentence there?


Anyone that has had a radio install or installed their own radio and are having K wire issues. There's actually a warning in the packaging given by most manufacturers not to hook up the wire.


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## AudiMick (Sep 1, 2010)

BoostedGLS0218 said:


> I would think that the aftermarket harnesses might be different from each other brand to brand, right?


Clarification.

There are two harnesses , one comes with your stereo and is specific for that head unit and brand.

The other harnesses are purchased separately to convert the VW wire loom and plugs into universal wiring.

You splice the 2 harnesses together matching up the wiring colors which should be standard colors.

http://www.the12volt.com/caraudio/headunitharness.asp

Then plug the new harnesses into the VW plugs and plug the other end into your head unit. 

Have no idea why the antenna thing came up nothing to do with K-line.


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## NFrazier (Jul 22, 2006)

AudiMick said:


> Clarification.
> 
> There are two harnesses , one comes with your stereo and is specific for that head unit and brand.
> 
> ...


LMAO, wellllllll if you are familiar with the VW (or euro) iso-harness, most come without two pins pinned. One of which is a blue/white (EIA color for remote turn on) and blue (EIA color for powered/amplified antenna). You need to pin these wires in Mercedes/Land Rover for the factory amplifier/amplified antenna. In a VW if you pin one of these, that's the location of the k-wire in the factory harness.:wave:


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## AudiMick (Sep 1, 2010)

NFrazier said:


> LMAO, wellllllll if you are familiar with the VW (or euro) iso-harness, most come without two pins pinned. One of which is a blue/white (EIA color for remote turn on) and blue (EIA color for powered/amplified antenna). You need to pin these wires in Mercedes/Land Rover for the factory amplifier/amplified antenna. In a VW if you pin one of these, that's the location of the k-wire in the factory harness.:wave:


Why would someone buy an aftermarket harness for a Mercedes or Landie to install in a VW?

I merely suggested not permanently modifying the car wiring, instead cut the offending wires in the aftermarket harness.

Not rocket science.


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## NFrazier (Jul 22, 2006)

AudiMick said:


> Why would someone buy an aftermarket harness for a Mercedes or Landie to install in a VW?
> 
> I merely suggested not permanently modifying the car wiring, instead cut the offending wires in the aftermarket harness.
> 
> Not rocket science.


In europe they used a standard harness (it looks like http://www.sonicelectronix.com/item_12610_Metra-71-1784.html) So you can use a Merc or LR harness for a VW and a VW/Audi harness for a Merc or LR. The only difference was if u used one for the other ud have to swap the constant and accessory. Also in the Merc and LR they used the spot where the K wire would be in the VW/Audi for the factory amplifier turn on and power/amplified antenna (they use the same wire for both). Its the same style plug but depending on the brand there's a slight difference.

I am saying that there's no need to pin these spots in the harness in these cars anyways. If there's an issue with the Kwire, it was installed wrong, plain and simple. Easy solution is to not pin it, or if u did, cut it and tape it or cap it off.

Not rocket science but people **** it up every day. Keeps me employed.

Famous words of a ton of DIYers "I/my buddy hooked up everything right, it just doesn't work" umpkin:


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