# Mk3 gti vr6 OBD2 port not responsive



## VRcrazed3 (Sep 29, 2012)

Hey guys sorry if there is already a thread about this. I work at a VW dealership and tried to reset my CEL yesterday at work but it would not connect at all. Since then I have tried 3 other scan tools and checked every fuse. The OBD2 port does have power too. Even tried resetting the ecu. Nothing has worked and I need to do my emissions test soon. Any suggestions as to why this is happening and what I should do? And Any other ways to reset the CEL. I'll try just about anything at this point. Thanks


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## Eric D (Feb 16, 1999)

Check that the grey with white stripe wires are plugged into the junction box above the fuse box.
If you have an aftermarket radio and a plug and play harness adapter, the issue could be the K-line is shorted to +12v.
That happens only if a plug and play harness adapter is used, pin 3 is tied to pin 1 on the black connector.
The easiest thing to due is cut the wire.

Other than that, since you work at the dealer, get a schematic and start troubleshooting.


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## Uwe (Jan 16, 2000)

If it has an aftermarket radio, read this:
http://www.ross-tech.com/vag-com/aftermarket-radio.html

-Uwe-


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## [email protected] Parts (Nov 27, 2006)

In addition to Uwe's suggestion.

Please verify the TV Bridge connector bus above the fuse-box, which brings all the K lines to a merge point. Make sure nothing is plugged in, just for the sake of it.

Can you speak with any other module such as airbag or abs?

Use the TV bridge to isolate the module which is cluttering up the K line. 
Do a continuity test from the ALDL and ecu to bridge to check the current tracks.


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## cabrlicious (Jan 27, 2008)

*OBD port wiring*

Back from the dead..

OK to the very helpful folks who originally answered this thread:

I have the same issue, except I know exactly why it's not working. The k-line junction box is un-populated -- this is a swap car that literally has some loose ends, so what i would like to know is where exactly do the individuals that belong plugged into that junction box actually originate from? I was groping around trying to find them coming from the engine bay harness near the firewall as well as near the F G1 and G2 connectors behind the fuse panel, but its dark out and the end of my day so I gave up for the night.


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## [email protected] Parts (Nov 27, 2006)

_



Please verify the TV Bridge connector bus above the fuse-box, which brings all the K lines to a merge point.

Click to expand...

_Yup!


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## hubb412 (Aug 16, 2006)

[email protected] Parts said:


> In addition to Uwe's suggestion.
> 
> Please verify the TV Bridge connector bus above the fuse-box, which brings all the K lines to a merge point. Make sure nothing is plugged in, just for the sake of it.
> 
> ...



Sorry to bring this thread back from the dead. 

Jack, if you're still here - I'm assuming the TV Bridge connector is that connector that takes all of the similar-colored connectors together. I'm assuming that the k-line connectors are the yellow ended connectors? 

I have disconnected all of the yellow connectors and i'm still not getting communication.


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## stan067 (Feb 25, 2010)

Jack got kicked out. He was the best but was an A$$hole and hurt others feelings. So Vortex booted him to create a *safe space* for peoples feelings.
Even though he was the best at actually helping people fix cars. This is the world today protecting their feelings is more important then helping fix the car.

K line is simple every module has a wire and it goes to the bridge above fuse card. This bridge connects them all together. And the DLC also goes there.
So modules and scanner connect through this bridge. If the radio k wire is shorted all communication in the K line is lost to all modules. Radio was the big one
they hooked up the k wire to ground or power when installing aftermarket radios.

The bridge is a bunch of single k line wires each one going to a module. You could unplug one at a time here rather then go unplug each module one at a time.

ABS and Radio were the ones that usually shorted.

The bridge is basically a splice point.

Good Luck


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## hubb412 (Aug 16, 2006)

stan067 said:


> Jack got kicked out. He was the best but was an A$$hole and hurt others feelings. So Vortex booted him to create a *safe space* for peoples feelings.
> Even though he was the best at actually helping people fix cars. This is the world today protecting their feelings is more important then helping fix the car.
> 
> K line is simple every module has a wire and it goes to the bridge above fuse card. This bridge connects them all together. And the DLC also goes there.
> ...


Thank you for the help!

So this is the bridge:










And this is the diagnostic board:










Correct?

I read another post today that talked about the cluster potentially being at fault. I'm running the entire car on the mk3.5 Cabrio harness / components with the exception of the vr6 engine harness.

Today I swapped in the vr6 cluster and cluster harness and now I don't get connection at all through the obd2 port. 

I'm guessing there's something to do with the 3 connectors that don't have a home from the cluster harness. 











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## hubb412 (Aug 16, 2006)

*woooooo!*

I HAVE COMMUNICATION WITH THE ECU!!

Turns out that trying to get vag-com working in a mk3.5 cabrio vr6 will not work if you have the mk3.5 cluster installed, you must have the mk3 vr6 cluster and associated harness connected.

In my infinite wisdom i pulled fuse 21 last night and forgot to reinstall it. That fuse is required for obd2 port operation.


I only have 2 faults in the ECU - both related to secondary air which has been deleted.

I can't communicate with ABS which is required as i need to bleed the air out of it, but i'm feeling much better right now. On to chasing down why i can't communicate with ABS.

Thanks dudes, will post more shortly.


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## hubb412 (Aug 16, 2006)

stan067 said:


> Jack got kicked out. He was the best but was an A$$hole and hurt others feelings. So Vortex booted him to create a *safe space* for peoples feelings.
> Even though he was the best at actually helping people fix cars. This is the world today protecting their feelings is more important then helping fix the car.
> 
> K line is simple every module has a wire and it goes to the bridge above fuse card. This bridge connects them all together. And the DLC also goes there.
> ...




Heya, 

I think i found the k-line connector for the ABS plug - it's a grey connector with a black/grey wire. This matches wire color with the bently and i *think* it's coming through the firewall with the ABS loom. 

My question for you is - should i be able to get continuity from the grey k-line bus over to the DLC subpanel? Based upon your post it would seem that I should be, however I am not. It only makes sense to me that the DLC subpanel should have continuity to the grey k-line connector bridge, otherwise how would they communicate?


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## stan067 (Feb 25, 2010)

Because your building a Frankenstein car here I really can't help much. So don't take what I say as the truth.

Basically the first pic is not the bridge two many wires.

In a mk3 you only have ABS, ECU, Airbags, Auto trans, radio and DLC

Are you putting a MK4 motor in this? AFP VR6? or a MK3 VR6 AAA?

If you can log in to ECU then K line is not shorted. If it was you can't find any module.

All I can tell you is 1 wire for each module you have and the 1 for the DLC.

The scanner uses 1 wire to communicate DLC goes to the bridge and the finds ECU, or whatever else is plugged into the bridge.
As long as the module has power and ground and a K line going to the bridge the scanner should find it. 

The second pic is the bridge all single k line wires.

Good Luck


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## hubb412 (Aug 16, 2006)

stan067 said:


> Because your building a Frankenstein car here I really can't help much. So don't take what I say as the truth.
> 
> Basically the first pic is not the bridge two many wires.
> 
> ...


Heya Stan, Great Post!

Thanks for your help.

This is an OBD2 AAA swap from a 96 mk3 into a mk3.5 cabrio. I have confirmed by continuity test that the ABS k-line connector is NOT plugged into the bridge. I'm going to start by trying different combinations of wires into the k-line bridge. 

Are all k-line connectors typically grey? What is the link between the k-line bridge and the DLC daughterboard?


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## o2bad455 (Aug 22, 2003)

I had a similar problem with a 97 GTI VR6. It turned out to be a bad ABS module pulling one of the OBD2 diagnostic port signals out of range. Disconnecting the connector at the under hood ABS module allowed OBD2 port to function again.


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## hubb412 (Aug 16, 2006)

hubb412 said:


> Heya Stan, Great Post!
> 
> Thanks for your help.
> 
> ...


So I got it working. It turns out that in a mk3 all k-line connectors just connect to the DLC daughter board. My abs module wasn't communicating for that reason as well as the ABS wasn't getting switched 12v on pin 16 of the connector. 


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