When installing a trailer hitch on a 2007 and later VW Touareg 2, the early version of the instructions may have left out a step. The instruction should read to install an additional fuse in position SC41 on the right side of the dash. If this fuse is not installed, the trailer module may display a terminal 15 implausible signal fault code and some trailer lamps will not function.
Additionally, in order to activate the trailer brake lamps after installing the trailer hitch kit, the module coding must be changed. The change is to add “1” to the current coding.
For example, the earlier models come coded with a “1” and must be changed to a “2.” The later modules should come coded to “16385” and will be changed to “16386.” This will not affect vehicle lighting.
The Gateway Long coding must also be changed on the Touareg 2 models. To code run the test plan for coding the diagnostic data bus (Gateway) through GFF or Guided Functions and select the “trailer function” line. When reading out the coding to test, make sure it reads “coded” after the “trailer function” line.