The F81B‑14B205‑FB is a Ford Super Duty Multifunction Electronic Control Module (GEM) used in 1999‑2001 F‑250/F‑350/F‑450/Excursion trucks for air suspension, 4×4 control and other vehicle functions. Common failure points include burned or tripped relays on the module’s power rail, degraded capacitors or solder joints due to vibration, and intermittent communication faults with the vehicle’s CAN bus. Begin diagnostics by verifying a clean 12‑V supply to the module, inspecting all connectors for corrosion or loose pins, and checking for diagnostic trouble codes via an OBDII reader; if no fault codes appear, perform a continuity test on the module’s internal I/O circuits.[oss-gpt-20b]