Hi I have an 2002 Suburban and the rear window wiper only seems to work sometimes. Any ideas where to start my search?

 

IF its works sometimes then the fuse is probably good and you have an intermittent connection somewhere or possible the motor is going out...
I'd suggest gaining access to the rear wiper motor and checking for voltage with the wiper in full on mode...
Simply reseating the motors electrical connection may resolve the issue...