VCDS no connection, K2 line short to ground!

[jpaudio]

Hi fellow members. Unfortunately I am not able to communicate with VCDS cable in my Audi A4 1.8TQ B6. This came up (I cannot put my hand to fire...) after a re-connection I did near RNS-E calbling introducing a BOSE audio system. The VCDS cable in TEST reported back that communication is questionable, K1 Line OK, K2 Line short to ground! I checked cable in another car and it is working perfect! To be sure about, I visited a local repair shop and ussing original VAS and an aftermarket Delphi diagnostic system, they managed to communicate with bus but not with Xenon and Navigation modules. All other modules replied and communicated with no problem. Have you any idea how I can check cabling or how to remove one by one connectors of these modules in order to determine where is the fault? Is this fault happened to anyone of you before? I double check RNSE cable connections (that was my last intervention) and I didn't found any fault. Also looking at CAN Bus drawings (by ELSA) I realized that there are three communication circuits under CAN name, Connection CAN (I assume the power-engine one), Convenience CAN and Infotainment CAN, All start from dash panel and according to diagrams are independent. Somewhere also a Navigation CAN appears but it is not routed from dash panel.
Thanks in advnace for your kind attention.
Regards,
John

[onceover]

I've heard of this happening when installing aftermarket radios, so it very well could be the same thing since you just played with the RNS-E.

Try unplugging it completely and see if you can get VCDS to connect.

[jpaudio]

Radio is the original one and installed 3 years now. Only cable arrangement done because of Bose upgrade. The strange thing is the Xenon communication issue, is this relative to RNSE cabling?
John

[strtdrms]

Experiencing something similar. After installing my rnse, I get the k2 line short to ground. Unplug rnse and I can connect fine.

[lyates1987]

Experiencing something similar. After installing my rnse, I get the k2 line short to ground. Unplug rnse and I can connect fine.

Do you mean unplug RNSE from the harness at the back? I'm bout to install one and just want to be sure just in case I run into this issue.

[strtdrms]

Yeah. Just unplug the quad connector in the back. Should be able to connect then

[jpaudio]

Thanks for all your reply and concerns, but RNS-E was working perfect since almost 4 years now. In addition no programming will be possible in case of unit's CAN bus lines disconect. I also don't be able to connect to Xenon module either. I will investigate deeper this and come back with findings.
Regards,
John

[diagnosticator]

Use an Ohm meter connected to the K2 line and chassis ground., There must be no continuity also known as infinity Ohms resistance. If the resistance to chassis ground is less than infinity high Ohms, then the short to ground must be found and fixed. Alternatively, run a new K2 line in parallel connection with the existing K2 lines with the original K2 line disconnected from the Navi HU. Run the K2 line outside of the harness secured with tie wraps. This will bypass the short.

[jpaudio]

Hi. Finally the problem found to be at K line cable (green/blue stripe) at same connector near power lines to RNS-E. Initially, I thought it was the ACC signal to unit. In this cable I connected + cable from rear view camera adpapter. Then trying "rewind" in my mind I realized that RNS-E don't need ACC power since power off (key off) is driven by BUS command. The connection I made created permanent low resistance to ground so no communication, at least for VCDS cable. Worthing to mention that VAS diagnostic and Deplhi after market one communicates with car K line BUS with no problem except Radio and Xenon modules (I assume same cable is going to both modules as well).
Thanks a lot for your valuable replies.
Regards from Greece,
John