To find it, you'll need to:
1. Look at the brake pedal: Carefully examine the brake pedal and its linkage. The switch might be a small, cylindrical or rectangular device mounted directly on the pedal or very close to it. It's often wired to a connector.
2. Trace wiring: If you can't spot it on the pedal, look for wiring harnesses near the brake pedal assembly. Trace the wires going to a switch; this will likely lead you to the brake light switch.
3. Consult a repair manual: A repair manual specific to your 1992 Chevy G20 van (and ideally specifying the conversion van's manufacturer, as this *might* influence its location) is the best resource for precise location. These manuals often have diagrams showing component locations.
4. Online forums: Search online forums dedicated to Chevy G20 vans or conversion vans. Owners might have discussed locating this switch, and you might find pictures or descriptions.
Safety Note: Before working on your brakes, always disconnect the negative battery cable to prevent accidental shorts or shocks. If you are uncomfortable working on your braking system, it is best to have it inspected and repaired by a qualified mechanic.
