Ford Repair: ford explorer 4 wd wont shift to 4wl, drive gears, 4 wd

Question
My friend has a Ford explorer, I'm not sure of the model, but I think it is a '91.  His problem is that it will not go to 4WL.  It shifts from 2W to 4WH and back with no problem, but it will not go to low at all.  Could you tell me what has to be made up in order for this shift?  The transmission neutral switch is working, because I had him check to see if it would start in neutral and not in drive gears. Also could you tell me where all the wires going into the shift motor terminate so we can check for a broken wire?  Thanking you in advance,  

Ron Tate  

Answer
Ron,

Odds point to the shift motor or switch being failed.  The wires attached to the motor go into the main harness and up to the PCM.  The shortest way to test the system is to remove the shift motor while still connected to the harness and watch for proper movement in the motor.

Patrick