Chrysler Repair: Jeep 2.7 Ltd CRD rear wiper, rest position, time mode

Question
Hi, The rear wiper on my Jeep now only works intermittently.Would it be the wiper motor itself which is failing or the Stem switch...or is there something else that I have missed?
On delay it only goes across without returning...then it goes back to the rest position after 30 secs or so.
On the wipe all the time mode it operates now and again.
Any help would be appreciated.
Best regards.
Mick.

Answer
It could be a bad ground.I would look at the wiring at the motor and through the liftgate.If this vehicle is in the States (which I'm thinking not) it should still be under warranty.I don't know what export warranty is.For me rear wiper problems have most always been the motor.