* Powertrain Control Module (PCM): This is the most significant one, handling engine functions. It's usually located near the engine, often under a cover, possibly on the driver's side inner fender well.
* Body Control Module (BCM): This controls various body functions like lights, power windows, and locks. Its location varies, but common spots include under the dash or in the center console.
To find these modules, you'll need a 1991 Chevy Caprice Classic repair manual. The manual will have diagrams showing the exact location of each module, as well as wiring diagrams. You can often find these manuals online, through auto parts stores, or at libraries.
