Problems with the 4-wheel drive (4wd) in the 2005 Ford F-150 may include dangerous locking of the front driveshaft due to leaky vacuum lines from the integrated wheel ends. Owners also reported that the vacuum solenoid can become locked in the hubs while driving. When the control module verifies the completion of a transfer case shift to 4WD using the contact plate position sensors, it activates the high-vacuum solenoid, supplying a vacuum of at least 11 in.-Hg to the hub locks for no longer than 60 seconds. This engages the hubs, which remain engaged after the vacuum source is interrupted.When the module verifies a shift to 2WD, it activates the low-vacuum solenoid, which supplieS6 to 7 in.-Hg vacuum to the hub locks for no longer than 30 seconds, disengaging the hubs, giving us 2WD.
William P.
April 9, 2020
Problems with the 4-wheel drive (4wd) in the 2005 ford f150 may include dangerous locking of the front drive shaft due to leaky vacuum lines from the integrated wheel ends. The vacuum solenoid can become locked in the hubs while driving. The actuators may need replacing. Also, the 4wd shift motor can frequently malfunction so that the 4x4 dash light won't come on to indicate that 4-wheel drive is engaging or the hoses may crack.
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