Presuming you're referring to the front windshield wipers, and not the rear hatch wiper, it probably is an electrical problem. Could be a defect in the wiper switch (e.g., bad contact or defective internal printed circuit board], or a faulty internal position switch in the wiper motor assembly itself. These are normally not repairable parts. Or it could be a broken wire, although this is less likely unless work was done (mechanical, body) that could have disturbed/damaged wiper-related wiring.
I've attached the 2007 front wiper wiring diagram.