Just thought I'd post what I found when changing the rear wiper motor. Firstly the motor would not stop and constantly swept across the rear screen. The problem started about 2 months ago and the only temporary fix I did was pull the fuse out. However like the first wiper motor I had that blew, this one was not caused by the leaky washer pipes.
Before pulling the fuse out, the rear end inside of the car started to fill with white smoke that had the awful electrical burning smell.
After pulling the motor this evening I discovered that the electronics inside have literally melted away and burnt out. I'm not sure if this would eventually lead to a fire but thought it's something worth mentioning on here. If your rear wiper motor is playing up I'd be cautious to leave it. This is my second motor to stop working.
There's a couple of threads I found on google where some people wiper motor caught fire and took the plastic boot trim with it. Anyway here's a couple of pics.
The car is a 2005 A3 TDI 3 door