2000 Expedition, awd 4h 4l. I put it in 4h to get out of my driveway after we got dumped on by about a foot of snow, after I got out on the highway I switched it back to awd. I noticed that it still pulled like it didn't disengage. It finally disengaged after 2 or 3 time of switching it back to 4h to awd. I thought maybe it had ice build up that was causing it to stay in 4h. Anyone else ever notice anything like this?

 

I'd start with the transfer case shift motor, but as you can see below, it might be one of MANY possibilities.

PINPOINT TEST B: THE VEHICLE DOES NOT SHIFT BETWEEN A4WD AND 4WD MODES PROPERLY

Note:
Complete the entire pinpoint test related to the symptom before replacing the GEM.
² B1: CHECK THE IGNITION STATES
² B2: RETRIEVE THE RECORDED GEM DTCS FROM BOTH CONTINUOUS AND ON-DEMAND SELF-TESTS
² B3: CHECK THE 4H INDICATOR
² B4: CHECK THE 4L INDICATOR
² B5: MONITOR THE MODE SWITCH GEM PID 4WD_SW
² B6: CHECK THE MODE SWITCH
² B7: CHECK CIRCUIT 780 (DB) FOR OPEN
² B8: CHECK CIRCUIT 780 (DB) FOR SHORT TO GROUND
² B9: CHECK CIRCUIT 780 (DB) FOR SHORT TO POWER
² B10: CHECK CIRCUIT 682 (DB) FOR OPEN
² B11: CHECK CIRCUIT 682 (DB) FOR SHORT TO POWER
² B12: MONITOR THE GEM PIDS MTR_CCW AND MTR_CW — GEM ACTIVE COMMAND CW/CCW ON
² B13: MONITOR THE GEM PIDS MTR_CCW AND MTR_CW WITH THE GEM ACTIVE COMMAND CW/CCW SET TO ON
² B14: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT RELAYS COILS — CIRCUIT 704 (DG/LG)
² B15: CHECK CIRCUIT 781 (OG/LB) FOR OPEN
² B16: CHECK CIRCUIT 782 (BN/WH) FOR OPEN
² B17: CHECK CIRCUITS 781 (OG/LB) AND 782 (BN/WH) FOR SHORT(S) TO GROUND
² B18: CHECK CIRCUIT 782 (BN/WH) FOR SHORT TO POWER
² B19: CHECK CIRCUIT 781 (OG/LB) FOR SHORT TO POWER
² B20: CHECK THE TRANSFER CASE SHIFT RELAYS COILS
² B21: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT MOTOR — GEM ACTIVE COMMAND CW/CCW ON
² B22: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT RELAYS SWITCH SIDE — CIRCUIT 704 (DG/LG)
² B23: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT MOTOR — GEM ACTIVE COMMAND CW/CCW OFF
² B24: CHECK CIRCUITS 777 (YE) AND 778 (OG) FOR SHORT(S) TO POWER
² B25: CHECK CIRCUITS 777 (YE) AND 778 (OG) FOR OPEN
² B26: CHECK CIRCUIT 777 (YE) FOR OPEN
² B27: CHECK CIRCUIT 778 (OG) FOR OPEN
² B28: CHECK THE GROUND TO THE TRANSFER CASE SHIFT RELAYS — CIRCUIT 57 (BK)
² B29: CHECK THE CONTACT PLATE SWITCHES — MONITOR THE GEM PIDS PLATE_A, PLATE_B, PLATE_C, AND PLATE_D
² B30: MONITOR THE GEM PID PLATE_A FOR OPEN
² B31: CHECK CIRCUIT 771 (VT/YE) TO THE CONTACT PLATE SWITCH A
² B32: CHECK CIRCUIT 771 (VT/YE) FOR SHORT TO GROUND
² B33: CHECK CIRCUIT 771 (VT/YE) FOR OPEN
² B34: CHECK CIRCUIT 771 (VT/YE) FOR SHORT TO POWER
² B35: CHECK CIRCUIT 762 (YE/WH) FOR SHORT TO POWER
² B36: CHECK CIRCUIT 762 (YE/WH) FOR OPEN
² B37: MONITOR THE GEM PID PLATE_B FOR OPEN
² B38: CHECK CIRCUIT 770 (WH) TO THE CONTACT PLATE SWITCH B
² B39: CHECK CIRCUIT 770 (WH) FOR SHORT TO GROUND
² B40: CHECK CIRCUIT 770 (WH) FOR OPEN
² B41: CHECK CIRCUIT 770 (WH) FOR SHORT TO POWER
² B42: MONITOR THE GEM PID PLATE_C FOR OPEN
² B43: CHECK CIRCUIT 764 (BN/WH) TO THE CONTACT PLATE SWITCH C
² B44: CHECK CIRCUIT 764 (BN/WH) FOR SHORT TO GROUND
² B45: CHECK CIRCUIT 764 (BN/WH) FOR OPEN
² B46: CHECK CIRCUIT 764 (BN/WH) FOR SHORT TO POWER
² B47: MONITOR THE GEM PID PLATE_D FOR OPEN
² B48: CHECK CIRCUIT 763 (OG/WH) TO THE CONTACT PLATE SWITCH D
² B49: CHECK CIRCUIT 763 (OG/WH) FOR SHORT TO GROUND
² B50: CHECK CIRCUIT 763 (OG/WH) FOR OPEN
² B51: CHECK CIRCUIT 763 (OG/WH) FOR SHORT TO POWER
² B52: CHECK THE SHIFT MOTOR
² B53: CHECK CIRCUIT 994 (WH) FOR OPEN
² B54: CHECK CIRCUIT 994 (WH) FOR SHORT TO GROUND
² B55: CHECK CIRCUIT 994 (WH) FOR SHORT TO POWER
² B56: CHECK CIRCUIT 994 (WH) FOR OPEN
² B57: CHECK CIRCUIT 994 (WH) FOR SHORT TO GROUND
² B58: CHECK CIRCUIT 994 (WH) FOR SHORT TO POWER

 

Looks like Buzzard gave you the complete check list.

I did get locked in 4L a couple of times before I had to replace the electric shift motor at the transfer case-----and this happened just in the cranking process (without shifting the transfer case switch).

I got "unlocked from 4L" by disconnecting the battery cable momentarily (apparently let the computer reset itself???).

The dealer suspected the GEM module-----problem turned out to be the shift motor.

Delta Dirt
Mississippi