Jeff has you on the correct trail...but...in spite of the AWD switch showing that it is "ON" I would first verify that you are actually delivering 12V to the connection Jeff's diagram illustrates by using a multimeter on the pins on the proximal side of the connector. If you do have 12Volts then clean the connector well, re-connect, and check the front drive again. If still no front drive then proceed to test the coil. If it test good, as Jeff said, your armature plate is likely warped. A caveat- I have seen several members post that although the coil tested good (and the armature plate was not warped) it still did not induce enough magnetic field to put enough drag on the armature plate to allow the sprag to engage. In those cases the coil and armature plate were replaced and the problem corrected.