Ford Truck Enthusiasts Forums

Ford F-150/F-250: Why Can't I Get Into or Out of 4WD?

F-150s and F-250s both suffer from the occasional bad vacuum line or busted locking hub. Your truck's 4WD isn't a simple system, but we've got some tips that'll help you figure out why it isn't working.

By Brett Foote - November 19, 2014

This article applies to the Ford F-150 (2004-2014) and the F-250, F-350 Super Duty (2005-2014).

Though not common, a 4WD system that won't disengage will make driving a real challenge. 4WD isn't meant to be driven on paved roads, and doing so extensively will damage the truck even further. Learn what might a cause an F-150 or F-250's 4WD system to become unresponsive below.

Materials Needed

  • Code reader
  • Socket or wrench set
  • Flat head screwdriver

Step 1 - Check the fuses

F-150s will have their fuse box in the engine compartment. Check the owner's manual to identify which fuses control the 4WD system. Replace a blown fuse with one of the same amperage. F-250s have a fuse box located under the passenger side, right hand foot well. Remove that plastic barrier to access the fuse box.

  • Check the owner's manual to identify which fuses control the 4WD system.

(Related Site: Vehicle Owners' Manuals - Ford.com)

  • 2008 Ford F-150 Fuse Diagram
    Figure 1. (F-150 2004-2010)
    F11 - feeds the A/C clutch relay and the 4x4 center axle disconnect solenoid
    F111 - feeds Clockwise (cw) motor 4x4 relay, counterclockwise (ccw) motor 4x4 relay
    F20, F29, F30 - Powertrain control module (pcm) stem.
  • 2014 F-150 Fuse Diagram
    Figure 2. (F-150 2011+)
    F20 - 4x4 module
    F29 - IWE solenoid
    F54 - run/start 4x4 module
    F68 - 4x4 module 4x3 e-locker.

Step 2 - Check for trouble codes

Connect an ODB scanner to the truck's ODB port and scan for diagnostic trouble codes. When something malfunctions in an F-150 or F-250, the computer stores a code for service technicians. This also holds true for the 4WD system. Typically, a code is accompanied by a check engine light or a big orange wrench on the dash. Some scanners will be able to reveal what the code means on the device, while others will simply provide the code. Most of the time you can figure out what the codes mean by searching the Ford-Trucks.com forums or by using Google.

  • Some trucks will display DTCs through the information center. Hold down the SET UP and RESET buttons next to the ignition key hole and turn the ignition without starting it. The truck should will display saved trouble codes then. If that doesn't work, use a scanner to check for codes.
Figure 3. Typical ODB location.

If you aren't getting any trouble codes, move on to step 3.

Step 3 - Replace the IWE solenoid

If the above steps don't work, it's likely the IWE solenoid has gone bad. If the solenoid stops working, there will be no vacuum to work the 4WD actuators and engage the hubs. Some early solenoids did not have the rain cover that newer ones have and could short out if water runs down the cowl on top of it. This is only a real issue on some models of the F-150.

  • Check the vacuum lines and replace the IWE solenoid if the automatic locking hubs are acting up.
Figure 4. IWE solenoid outlined in red.

Related Discussions