You're in luck, I just fixed one the other day doing the same thing. I am going to explain to you how the 4X4 system works and what can be done to fix it.
You have a transfer case that locks in 4wd and 4wd lo. Then you have a solenoid called an IWE (independent wheel end). It release vacuum to the hubs to allow the hubs to enge the axle on each side. There are a few things that happens. If you have the old style IWE solenoid, it will leak water into it and freeze and cause the 4X4 to do weird things. You must replace the solenoid to fix that. Then you have to inspect the vacuum lines going from the solenoid to the hubs. You may have a vacuum leak. Then if all of that is good, you may have a vaccum hub seal bad. If it gets to that point, you need to inspect the hub and the seal. The teeth on the hub get worn from the false engaging and will be worn.
I am going to look up the service bulletin and some manuals for you and will post them asap.
Thanks for asking!
Here is the service bulletin:
|LINCOLN:||2006 Mark LT|
Some 2004-2006 F-150 and 2006 Mark LT 4X4 vehicles built before 4/24/2006 may exhibit a noise in*****from the front Integrated Wheel Ends (IWE) and/or the 4X4 system being inoperative. The IWE solenoid may have ingested water and passed it to the IWE system causing water contamination in the vacuum portion of the system. A shorted IWE solenoid can set the codes C1979 and C1980. If either code is present, the 4WDH light will be inoperative.
Use the following Service Procedure to check and repair the 4X4 system.
- Replace the IWE solenoid. Torque the new design bracket and solenoid to 62 lb-in (7 N-m). It will be necessary to remove the vacuum lines from each IWE down at the wheels to check for water being present.
- If no water is present at the vacuum line at the IWE, install the new solenoid with bracket. Reconnect all vacuum hoses.
- If water is present allow it to drain from the vacuum lines. Then follow the updated procedure outlined in 2006 Workshop Manual (WSM) on-line version, Section 308-07A, Pin Point Tests B21 and B22. These tests checks IWE leak rates with vacuum and will remove any residual water from the IWE. Reconnect all vacuum hoses.
- If the IWE looses vacuum quicker than specification. Refer to WSM, Section 204-01B for normal diagnostic procedures.
|PART NUMBER||PART NAME|
I cannot find all of the pictures that I want. This may help. Here is a description of the solenoid operation:
Integrated Wheel End (IWE) System
The integrated wheel end (IWE) system consists of the:
- Vacuum reservoir
- IWE solenoid
- IWEs (spring loaded vacuum hubs)
- Vacuum hoses
- Check valve
The IWE system uses vacuum hubs that engage or disengage the front wheel hubs from the front halfshafts.
The IWE solenoid receives engine vacuum from the vacuum reservoir.
When the four wheel drive system is in 2H mode, 4X4 control module (PCM) supplies a ground path to the IWE solenoid to apply vacuum to the integrated wheel ends (disengaging the front hubs from the front halfshafts). In 4WD mode, the 4X4 control module (PCM) does not supply the ground path to the IWE solenoid, vacuum is not applied to the integrated wheel ends and an internal spring keeps the front hubs engaged to the front halfshafts.