Gremlin living in rear wiper

Hi everyone,

I've got a gremlin living in my 2012 estate's rear wiper.

Working ok for some time, then give up and working again in cycles. 

Don't think it's the rear door lock as the ambient light dims after closing the boot lid.

I tried some tracking with VCDS and found an advanced measure value for wiper signal in central electrics.

Default position shows 0.0

Single wipe shows 1.0

Interminent wiping shows 2.0

Slow continuous wiping shows 3.0

Fast continuous wiping shows 4.0

Activate front screenwash shows 5.0

Activate rear wiper shows 0.0

Activate rear screenwash shows 0.0 (not a wiper signal)

Tried to perform an output test on rear wiper motor, but without any kind of response.

Anyone with VCDS with functional rear wiper to look what command should show when the stalk is in position for Activate rear wiper? 

What could cause the problem?  

Thanks