Will Not Shift Into 4WD OR 4 WD

Hi falcondriver,

I have the diagnostic procedures here and hope it helps. If you need additional info, feel free to ask.

TEST D: 4WD LO &/OR 4WD HI INDICATOR LIGHT NOT OPERATING PROPERLY

NOTE: Steps 1-3 pertain to power supply circuits.

1. Check Voltage At Fuse No. 15 (5-Amp) - Turn ignition off. Using voltmeter, measure voltage at terminal No. 1 on fuse junction panel fuse No. 15. If voltage is 10 volts or less, go to next step. If voltage is greater than 10 volts, go to step 4).
2. Check Fuse Junction Panel Fuse No. 15 (5-Amp) & Power Distribution Box Fuse No. 22 (50- Amp) - Inspect fuse junction panel fuse No. 15 (5-amp) and power distribution box fuse No. 22 (50-amp). If both fuses are okay, go to next step. If either fuse is blown, replace fuse. Clear DTCs and retest system. If fuse blows again, inspect circuit for short to ground.
3. Check Circuit 1052 (Tan/Black Wire) For Voltage - Disconnect fuse junction panel connector C243. See Fig. 2. Measure voltage between ground and terminal No. 11 on fuse junction panel harness connector. See Fig. 3. If voltage is 10 volts or less, repair open Tan/Black wire. Clear DTCs and retest system. If voltage is greater than 10 volts, replace fuse junction panel. Clear DTCs and retest system.
4. Check Ignition States; Monitor GEM PID IGN_GEM - Turn ignition off. Connect NGS tester. Depress clutch pedal (if applicable). Monitor Generic Electronic Module (GEM) Parameter Identification (PID) Ignition Switch Status (IGN_GEM) while turning ignition switch through START, RUN, OFF and ACC positions. If values agree, go to next step. If values do not agree, see STEERING COLUMN SWITCHES article in the ACCESSORIES/SAFETY EQUIPMENT section.

NOTE: In next step, if DTC B1342 is retrieved, replace GEM. Clear DTCs and retest system.

5. Retrieve DTCs - Retrieve and document continuous DTCs. Clear continuous DTCs. Retrieve on- demand DTCs. If DTCs are recorded, go to appropriate step(s). See DTC/TEST OR STEP table. If no DTCs are retrieved, go to next step.

DTC/TEST OR STEP
DTC - - - - -Go To TEST/STEP
P1804 - - - D/6
P1806 - - - D/6
P1808 - - - D/6
P1810 - - - D/6
P1812 - - - A
P1815 - - - A
P1820 - - - A
P1822 - - - A
P1824 - - - E
P1826 - - - E
P1828 - - - A
P1830 - - - A
P1832 - - - C
P1834 - - - C
P1838 - - - A
P1846 - - - A Or B
P1850 - - - A Or B
P1854 - - - A Or B
P1858 - - - A Or B
P1866 - - - A
P1867 - - - A
P1876 - - - C
P1877 - - - C
P1891 - - - A Or B

6. Check 4WD System Indicator Lights - Using scan tool, monitor PIDs 4WDHIGH and 4WDLOW. Set active command HIGH LAMP and LOW LAMP to ON, then OFF. If scan tool displays ON-B-, go to step 9). If scan tool displays OFFO-G and indicator light is continually illuminated, go to next step. If scan tool displays OFFO-G and indicator light is not illuminated, see appropriate INSTRUMENT PANELS article in the ACCESSORIES/SAFETY EQUIPMENT section.
7. Check GEM For Short To Ground - Turn ignition off. Disconnect GEM 22-pin connector. See Fig. 2. Turn ignition switch to RUN position. If indicator lights are illuminated, go to next step. If indicator lights are not illuminated, replace GEM. Clear DTCs and retest system.
8. Check Circuits 210 (Light Blue Wire) and 975 (Brown/Yellow Wire) For Short To Ground - Turn ignition off. Disconnect instrument cluster harness connectors. Measure resistance between ground and terminals No. 9 and 10 on GEM 22-pin harness connector. See Fig. 4. If resistance is 10 k/ohms or less, repair Light Blue wire and/or Brown/Yellow wire for short to ground. Clear DTCs and retest system. If resistance is greater than 10 k/ohms, replace or repair instrument cluster. Clear DTCs and retest system.
9. Check Circuits 210 (Light Blue Wire) and 975 (Brown/Yellow Wire) For Short To Voltage - Turn ignition off. Disconnect instrument cluster harness connectors. Disconnect GEM 22-pin connector. See Fig. 2. Measure voltage between ground and terminals No. 9 and 10 on GEM 22- pin harness connector. See Fig. 4. If voltage is present, repair Light Blue wire and/or Brown/Yellow wire for short to voltage. Clear DTCs and retest system. If voltage is not present, go to next step.
10. Check 4WD System Indicator Lights - Using scan tool, monitor PIDs 4WDHIGH and 4WDLOW. Set active command HIGH LAMP and LOW LAMP to ON. If scan tool displays ON- B-, replace GEM. Clear DTCs and retest system. If scan tool does not display ON-B-, repair or replace instrument panel, see appropriate INSTRUMENT PANELS article in the ACCESSORIES/SAFETY EQUIPMENT section.

Has anyone checked the transfer case shift motor to see if it is working or the vacuum in the front diff. so make sure the vacuum lines are all ok. Here is a pic of the motor and a vacuum diagram for the front diff. Hope this is helpful.

Here is the vacuum diagram.

Just trying to be helpful.

Does it seem like tis the engine are the transfer case binding? Can you please shoot a quick video with your phone so we can see what's going on? That would be great. You can upload it here with your response.