Where is flasher unit located on vw passat?

Probably depends on your model year, but in my 2002 passat the unit is actually part of the switch on the dash next to the radio. I used a small screwdriver to pry the switch out. Usually the cover pops off. If this happens I use 2 pliers to grasp the plastic rim that held the cover in place and pull straight out. As answered, the flasher and hazard switch button are all part of the same unit. The cover of the button will pry off with the screwdriver, leaving the switch (an LED sits on the face behind the translucent Hazard signal) exposed. Grasp the small plastic frame with one or two needle-nose pliers and pull straight out sharply, and the whole switch with its receiver unit will come out. Pull the switch apart from the receiver plug. The switch is only available at the dealer in the US (NAPA does not list it.) Mine cost $32. Replace the switch in reverse order, but the hazard light cover does not need to be removed -- just plug the new switch into the receiver plug (only fits one way.) Push it back into the dash, and you're done! You may have saved yourself $30 by replacing it yourself. (Would love to share pix but cannot upload into answer.)