I just got this from my Tech at the dealership.It seems VWOA has a fix for this and he e-mailed this to me.Here it is.No more warning signs anymore.
Here is the e-mail.
I hope that this helps. Remember that these resistors need to be metal oxide and from what engineering was telling VWoA these should be 3 watt. I know that we have used 1 watt type from Radio Shack and they work sufficiently in the past.
Please keep in mind that you have to identify what wires are what on your harness. They may vary depending on the manufacturer of the harness adaptor. I would assume that any LED light needs to be modified for correct operation. As I mentioned to you I would modify the adaptor "pig tail" harness so that the trailer would work properly on another vehicle and also that if you use another trailer with regular lights on this Touareg that it will also work properly.
If you need any more information about this fix, send me a e-mail and I will send you some more photos etc.
Here is the pic for how it is done.
Remember the resistor are 100 ohm 3 watt.