* Under the hood: Many engine control modules (ECMs) responsible for engine functions are located under the hood, often near the firewall or on the fender well.
* Under the dashboard: Modules controlling things like the climate control system, airbags, and anti-theft system are often found under the dashboard. Accessing these usually requires removing parts of the dash.
* Rear of the car: Some modules related to body control or other systems might be located in the rear of the car, though this is less common.
To find a specific module, you'd need a wiring diagram or a service manual for a 1998 Buick Regal. These diagrams will show the location of each module and its associated connectors. You can often find these manuals online through automotive repair sites or forums dedicated to Buick vehicles. Be cautious when working with automotive electronics; disconnecting the wrong module can cause problems.