Map the failed lamps
Record left/right, front/rear, low/high beam, park, stop, turn, hazard and fog behavior. Shared patterns reveal shared feeds, grounds or controls.
LIGHTING · 2002 · SYSTEM START
2002 Firebird Exterior-Lighting Diagnostic Start
Start lighting complaints by identifying which lamps and commands fail. The factory system has separate symptom paths for headlamps, doors, park, stop, turn, hazard and fog lamps.
APPLICATION: 2002 Pontiac Firebird / Formula / Trans Am. Configuration-specific equipment must match the vehicle before applying a circuit path.
Check aftermarket changes
GM diagnostic guidance specifically calls for inspecting aftermarket devices that can affect lighting operation. Alarm, DRL, LED and previous repair wiring matter.
Inspect connections before parts
Intermittent lighting faults are often connection/wiring problems. Reproduce the symptom and inspect the relevant circuit before replacing switches or modules.
DO NOT SHOTGUN SWITCHES OR MODULES
Choose the exact factory symptom path from the failure pattern, then prove the failed branch.
FPV RULE
OBSERVE → MEASURE → ISOLATE → PROVE → REPAIR → VERIFY. A symptom or DTC is a starting point, not a parts verdict.