[Ben01438]

I'm an auto electrician by trade and have lost count how many sets of parking sensors I've fitted to Audi's but never touched or dealt with tow bars.
Now my bro in law carries bikes on the back with a very good rack but has been tempting fate far too long now & has asked me to wire in a number plate board with lights.
I recall some Audis I've worked on have looms ready for a tow bar harness to be plugged in. Is this the case on a 53 plate 2.0 FSI A3 (sorry that's all I know about the car off the top of my head) or would a bulb failure indicator problem occur if I wire straight into the back of the light clusters?

Thanks