The Expedition is equipped with 2WD and 4WD vacuum solenoids attached to the upper RH side of the engine compartment dash panel, they alternately route vacuum to the vacuum motor which engages/disengages the center axle disconnect collar in the front axle assembly.
The 4x4 shift motor relay is a module containing two relays which, under the control of the GEM, shift the transfer case shift motor between the 2WD and the three 4WD modes.
The solid state clutch relay is used to activate the A4WD clutch within the transfer case.
Damaged wiring harness
Loose or corroded connector(s)
let it sit overnight
start engine place shifter in N foot on the brakes
and move mode switch to 2WD
if that doesnt work you have to have it checked for codes
Tuesday, February 15th, 2011 AT 4:02 AM