JonnyRotten

Ever since I picked up my Q5 and I've used the rear wiper, I've noticed that the arm doesn't always do a full sweep of the rear window.
Every once and awhile it starts to do the sweep of the arm and then just stops in a random spot that is not the home position. It could be at 12 o'clock, it could be 10 o'clock, it could be at 1 o'clock.
Sometimes the wiper arm operates as it should but sometimes it decides to just stop wherever it wants to and then go back to home on the next cycle. There's no pattern to where it stops.

Has anyone else had a similar experience?

Wires

Nope, mine always starts bottom right, does the swing up and returns to the same home position bottom right. Never had it stop anywhere else. Is it sweeping when you turn off the car? That might explain the odd stop locations.

JonnyRotten

No, it seems to just be stopping in random places when I first start using it and then after I've been driving for awhile it starts operating normally.
Whenever the arm stops in a random spot, I usually push the rear wiper button over and over (on/off) to get the arm back to the home position so I'm not driving around looking like the rear wiper is broken (especially since the thing is brand new and not some old rust bucket). Then I'll turn the rear wiper back on in a minute or so when the rear window needs wiping again and see how it reacts. If it starts to work properly I'll just leave it on and it seems to work properly, doing a full sweep at intermittent intervals.
It usually takes a few rounds of me pushing the rear wiper button and battling with getting the arm back to the home position, trying to figure out if the wiper is set to on or off (because there's no way of knowing, no light or indication) before I can get the whole thing to start wiping fully and intermittently.
I also have to focus on the driving and make sure that in all my frustration I'm not just focusing on the rear window. I've caught myself realizing that I'm not really paying attention to the road ahead of me.
I honestly don't want to take my brand new vehicle into the dealership for service until I have an idea of what's going on here so I'm hoping that there's a member of the forum who has some idea of how the whole rear wiper motor works.

Wires

Sounds like you'll need to take that in for warranty. Old school wiper motors used to be all mechanical with an off-centre type drive. Not sure if the rear wipers do that still, or if there is a servo/encoder deal to determine where the arm is in the motion of travel.

Regardless, what you have describe is not normal and would need to be warrantied. If it is electronic driven, they would be able to pull codes to validate.

JonnyRotten

I'll leave it for awhile and see it the issue works itself out especially since after 5 or 10 minutes of misbehaving it starts working normally and stays that way until the next time I drive the thing.

Wires

If it has a mechanical clutch (to prevent damage if someone should grab the arm), that might be the issue, which might cure itself if it had grease on the clutch/brake.