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Steve S
Steve S, Ford Technician
Category: Ford
Satisfied Customers: 1866
Experience:  10 years in Ford Dealership, Certified in: Auto Trans, Diesel Engines, Climate Control, Electrical D
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Ford F150 Pickup 4x4: 4-wheel drive issue; 2005 F150, 5.4L. Ive

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4-wheel drive issue; 2005 F150, 5.4L.

I've read several similar (but not identical) issues which seem to came back to the IWE solenoid, but my as mentioned I have not seen anything posted on this exact issue.

My truck seems to behave as if the 4WD is partially engaged about 90% of the time. While in 2WD the rear wheels consistently slip a little bit when accelerating from a stop, especially if turning from a stop, but not as much as if 4WD was fully engaged. Almost as if I was on a bit of sand or gravel, but I'm not. About 5% of the time the truck does not behave this way.
Hello there. You are correct in thinking that the solenoid is a major culprit in the 4x4 system problems on this model. Vacuum actually holds this system inXXXXXso if you are losing vacuum in the system because of a cracked line, mud in the lines, solenoid, or the hub actuator themselves then the truck defaults to 4x4. So if you can check the lines with a vacuum pump and they are ok then you are most likely looking at a faulty solenoid that cannot hold vacuum and therefore the vehicle feels like it is in 4x4. Thanks Steve
Customer: replied 5 years ago.
So can you confirm that this "partially engaged 4WD" is a possibility? It unclear to me if this is possible, as I only have seen references implying completely engaged or completely unengaged...
yes if you have a small leak where the engine can still pull some vacuum on the system but not total vacuum you could have basically partial engagement. Thanks Steve
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Customer: replied 5 years ago.
Hi Steve,

New info / follow-up.... I replaced the solenoid and that did not fix the problem. I also checked the vacuum pressure from the engine on that line & it was around 17 inches (I think that's normal). I also attached a hand vac pump to the line that runs from the solenoid to the hubs and that line held 18 inches of pressure with no leaking... also pulled and checked the vac reservoir & it was good. Can you point me in the right direction of what's left / most likely candidates?
Thank you,

When you pull vacuum on the lines to the hubs do the front wheels disengage from the cv shafts? The lines could be clogged with mud and that is why they hold vacuum. So lift the front end of truck up and spin the wheel with truck running the wheel should be disenaged from the cv shaft when you apply vacuum it should disengage. thanks Steve