2006 F-150 XLT, 5.4L, 4WD with manual shifter (so no transfer case motor)

First, yes I did read through (several times) the excellent "How To" thread: https://www.f150forum.com/f72/how-di...m-esof-186872/

The problem is that the passenger side wheel will not disengage from the half-axle. No matter what mode the truck is in, spinning the passenger wheel turns the half-axle. I replaced the passenger IWE and it didn't change anything. The driver side IWE operates normally (both with its own system and with the vacuum tool).

With the engine running and in 2WD, the vacuum tool shows the system is delivering 22" to both IWEs. The front drive shaft turns easily.

With the engine off, the vacuum stops and both wheels turn with their respective half-axle.

Testing with the vacuum tool showed both IWEs hold 22" easily. I tested the new IWE with the vacuum tool before I installed it and it worked normally.

So at this point, I'm stumped. I've verified that the vacuum system is delivering the proper vacuum to the IWEs (so no leaks), the IWEs hold a vacuum (so no leaks), the IWE on the driver side is working properly (must be ok), the new IWE installed on the passenger side worked properly before I installed it, and the transfer case is working properly (front drive shaft responds properly).

The only thing I'm wondering is, since it's a manual shift 4WD, maybe driving/moving the truck a bit would get it to work? So far I've done everything with both sides of the front end on jack stands and the tires off. Other than that, I'm out of ideas.

 

Its likely the vacuum solenoid.

 

Originally I thought that might be the case, but if it isn't functioning, how is it providing vacuum to both IWEs and shutting down when the engine is off and/or I shift to 4WD? Isn't that exactly how it's supposed to operate?

 

The IWE should stay under vacuum when the engine is off for a while. If the solenoid is going out, it could be leaking down and the lockers are starting to drag as soon as the engine is off. You may also see if you have a check valve on the vacuum that isn't keeping it under vacuum.

 

Ok, but that's not really the problem I'm having. It's about how the passenger IWE won't disengage when under 22" of vacuum (either from the solenoid or the vacuum tool).

Right, but that doesn't explain why the passenger IWE doesn't disengage when under vacuum.

Even if that was the case, it wouldn't explain my main issue.

In a nutshell, my problem is how the newly-installed passenger IWE won't disengage when 22" of vacuum is applied (either from the solenoid or the vacuum tool).

 

Oh, its likely bad out of the box then. Just because its new, doesn't mean its good.

 

Oh man I hope not. I tested it with the vacuum tool before I installed it and it worked fine. It fit and went in like it was supposed to, so I can't imagine what could have happened.

 

Ok, this is what I was referring to. How fast is it dropping vacuum? Does the passenger IWE actuator stay at 22" of vacuum with your tool (does it leak)? If you can get back behind that side, loosen the mount bolts on the actuator and make sure it's not off kilter or misaligned. If that doesn't make it behave as intended, it might be time to take it apart again.

 

I haven't checked that. I'll take a look though. Thanks!

The passenger IWE holds the vacuum with no problem, both when I tested it on the workbench and after I installed it.

That's what I'm afraid of.

 

How is the wheel bearing on the problem side? Seems like someone before when through a bunch of struggles like this and finally determined the wheel bearing was worn out and making the splines in the hub bind up