No doubt this topic has been covered a few times.

When I bought my car seven months ago I had an intermittent fault with my rear wiper, sometimes it would work, others not and I decided to live with it. Anyway it stopped for good this time. So I presumed it would be the fuse (probably not), wiring, the connectors or motor. So to isolate the fault quickly. I dropped the rear hatch trim. Got out my multi meter, tested the connector that went into the motor for a 12v feed and earthed it at the same time. Turned on rear wipers, feed was there, turned off wipers, 12v feed gone. So it looks like a faulty wiper motor. Whole job took me 10 minutes, first time I've done it, too. So it was very easy, really. 

Now to check to see if my years Bristol Street Motors extended warranty covers wiper motors or not, if it doesn't, I'll buy one myself and fit it. 

Above connector from the motor, I tested that with an earth from the lower hatch striker plate. 

Update. Took it into the dealers and their in-house warranty covers it, so I'll be having a new one fitted next week. Although I had to agree to an initial diagnostic fee of £126, which I wouldn't have to pay if it was covered under their warranty.