4 wheel drive does not work

It sounds like the 4wd actuator that is attached to the transfer case that is bad. Check to make sure it is getting power. If it is, chances are it is bad.

Let me know what you find.

Joe

Chances are there is a problem with the actuator on the transfer case. I need you to check to see if there is power to it when someone tries to engage the 4wd. If there is power, remove the actuator and have it checked. It is somewhat common on these vehicles for them to go bad.

Let me know if you have other questions.

Joe

You may need friends help on this. One needs to be in the truck and one under driver side of truck at the back of the transfercase. There is a little motor which inguages the transfercase. You won't need to start truck turn key to run while friend turns the selector switch to all spots and lightly tap on the little motor NOT Hard. Ford says you should activate it at least twice a month weather you use it or not just to keep it freed up. Let me know if this works and we go from there. 8) NOS

On the transfer case find the actuator motor, have someone press the buttons while you tap it with a hammer. If it works, the brushes, or contacts inside it are possibly corroded a bit, may work to free them up, if not check for power at this motor, if power is present, replace motor.
GEARMOTOR ENCODER ASSEMBLY Removal and Installation 1. Press the 4X4 HIGH button on the mode select switch (MSS). Fig. 53: Locating 4X4 High Button On The Mode Select Switch Courtesy of FORD MOTOR CO. 2. Raise and support the vehicle. 3. Disconnect the gearmotor encoder assembly harness connector. Fig. 54: Disconnecting Gearmotor Encoder Assembly Harness Connector Courtesy of FORD MOTOR CO. 4. Remove the bracket bolt and gearmotor encoder assembly mounting bolts and remove the gearmotor encoder assembly. Fig. 55: Removing Bracket Bolt And Gearmotor Encoder Assembly Mounting Bolts Courtesy of FORD MOTOR CO. 5. Remove the grease from the motor adapter and check for any nicks or burrs. If any damage is found, repair or install a new gearmotor encoder assembly as necessary. For additional information, refer to TRANSFER CASE - AUTOMATIC SHIFT . 6. To install, reverse the removal procedure. Ã Â Â Apply a coat of Multi-Purpose Grease to the gearmotor encoder assembly.

Remove the actuator, plug it in, and see if it is functioning. Pay attention to the power supply. Does it drop when the motor is engaged. If so, check the swith and relay again. They could work fine when not under a load.

I would check for power at the 4WD control module. You must select the 4WD on to check for power. The pins should be pin 8 and pin 17. These are the BK/WH and WH wires. This should be your power and ground pins. If do not have power, then find where you are loosing the ground or power.
If you have power to the conrol module, then there are a series of test that will need to be run to isolate the problem.