Brand new here and I come after lots of research/effort. Read old threads about trailer wiring for a 2013 Q5 and opted for a Tekonsha ZCI (zero contact) unit that you snap on to wires without splicing. I wanted to avoid splicing into wires to avoid potential need for dealing with dealer to adjust computer and rear camera beeping. I am not super mechanical but with some help installed the unit and it does not work - no functions send a signal. I am wondering if that high center brake light in hatch is confounding things. I am also wondering if using wires on hatch door (as in etrailer install video) is not as good as wires on passenger side rear fusebox. I called Tekonsha and they confirmed my connections were correct except for the taillight, for which they said I needed a yellow wire from my car (there is no yellow wire in the hatch door). However, I clearly found the taillight wire during testing. The tech said it may be that the voltage on my Q5 may be lower than the box can detect, and is sending me another unit with an updated chip that is better for lower voltages. I am unhappy and am wondering if I should just go with a regular old splice in to the wires system. Any help would be appreciated. Anyone use one of these ZCIs successfully or unsuccessfuly? Fuse area wires > hatch area? Which units should I use if I go traditional and do I need to go to Audi to adjust computer afterwards? Thanks.