Some 20182021 Expedition/Navigator vehicles may exhibit inoperative reverse lamps with DTC B1277 stored in the body control module (BCM). The vehicle may also exhibit the auto dimming rear view mirror becoming dark as soon as the key is turned on or is inoperative. This may be due to incorrect wiring of an aftermarket 5 pin jumper connector from a non-Ford windshield supplier that is causing a short to ground. To correct this condition, inspect if the windshield was recently replaced and verify the circuits in the 5 pin jumper connector located between connector C9440 and C9224 are routed in the correct pin location and adjust as necessary. Refer to the Wiring Diagram, Cell 124-10.
