I have an explorer with electric 4WD and auto-locking hubs. When switching to 4WD, whether High or Low, the dummy light on the dash comes on, but the front axle never gets power. The engine turns the front drive shaft whether in 2WD or 4WD, but the axle doesn't get power. From this observation, I assume that the 4WD engages in the front diff. Is this correct? Should the front drive shaft be getting power in 2WD, or is there a transfer case between it and the transmission that should disengage it? I don't know much about 4WD front ends yet, but the dummy light suggests that the electric motor that engages 4WD is doing its part.