The power steering fluid reservoir on a 1994 Plymouth Grand Voyager is typically located
under the hood, near the power steering pump. It's usually a small, clear or translucent reservoir with a cap. Look for a label that indicates "Power Steering Fluid" or something similar.
It's best to consult your owner's manual for the exact location and type of fluid to use. The manual will have diagrams and specific instructions. If you don't have the manual, you can often find a digital copy online through a site like Haynes or Chilton.