* Body Control Module (BCM): This is the most likely location for the main control functions related to the interior and exterior lights. The BCM is typically located under the dashboard, often near the steering column or under the instrument panel. Accessing it usually requires some disassembly.
* Individual switches and relays: Some lighting functions, like individual interior lights or the headlight switch itself, have their own switches and relays. These are scattered throughout the car's electrical system.
* Headlight switch: This controls the headlights directly and is a component involved in the overall lighting control, though it's not a "module" itself.
To find the likely culprit for a lighting problem: It's best to start by checking fuses first. Consult your owner's manual for a fuse diagram. If the fuses are okay, then you'll likely need a wiring diagram and possibly a mechanic or advanced diagnostic tools to pinpoint a problem within the BCM or other related components. A scan tool capable of reading BCM codes could be very helpful.
Because locating the BCM involves potentially significant disassembly, it's highly recommended that you consult a repair manual specific to your 1997 Buick LeSabre before attempting to access any modules under the dashboard. Improper disassembly can damage your vehicle's electrical system.
