The Body Control Module (BCM) in a 1991 Chevy Cavalier is typically located
under the dashboard, on the driver's side. However, the exact location can vary slightly depending on trim level and options. You might need to remove some trim panels to access it.
It's best to consult a repair manual specific to your 1991 Cavalier year and model to pinpoint the precise location with diagrams. A Haynes or Chilton manual would be helpful.