Vehicle: 2004 Ford Truck F150, 4WD, V8-5.4L SOHC, VIN 5, Automatic Transmission/Transaxle

Mileage: 98,887 miles

Problem: The owner says that the transfer case would not shift into 4WD when turning the switch to 4WD High or 4WD Low.

Case Details: The tech connected a scan tool and found no diagnostic trouble codes (DTCs). He also verified that the transfer case would not shift to 4WD Low or High.

With the 4WD motor unbolted from the transfer case and wires still connected, the technician used the scan tool to activate the motor counterclockwise. When he attempted to activate it clockwise, the motor wouldn't turn. He checked the wiring diagram and found that the two relays for the motor were in the auxiliary relay box one, located on the left fender well. They complete the circuit to turn the motor one way or the other. He swapped the relays, and motor would then activate clockwise but not counterclockwise.

Confirmed Repair: The technician decided to replace both relays because of their age. On the test drive, the 4WD worked as it should. Simple fix!