The fuel pump inertia switch on a 2008 Buick Lucerne is located
inside the passenger compartment, typically under the dashboard on the passenger side. It's often near the passenger's feet, sometimes behind a small access panel. You might need a flashlight to find it. The switch itself is usually a small, square or rectangular box with a button that can be pushed to reset it.
However, the exact location can vary slightly. It's best to consult your owner's manual for the precise location on your specific vehicle. The manual will have diagrams and instructions. If you don't have the manual, you can often find a digital version online through the Buick website or a reputable auto repair manual provider.