I recently posted about this rattle noise on my 04 4x4 thought I fixed it with new 4x4 solinoid. The noise used to happen mostly on highway or under load like pulling trailer. It didn't make the noise until I left work put truck in 4x4 and it stopped didn't make noise whole ride home. This morning same thing made noise pulling out to street hit 4x4 and it stopped made it to work no noise, is it IWE or maybe a bad solinoid also noticed a vacume line in th group from passenger side not connected to anything and couldn't find what it could be connected to????

 

just the solinoid did not fix my truck either. i replaced both IWE's too, no issues since replacing them.

 

Did you do IWE's yourself if so was it much work?

 

The IWEs have two lines coming from them. One is vacuum and one is just a vent line. Here's good general knowledge and trouble shooting;

https://www.ford-trucks.com/forums/8...then-some.html

...and here's replacing the IWEs. I didn't find the IWE replacement that difficult to do in my driveway.

IWE's: Removal & Replacing - F150online Forums

 

There are two vacuum lines off each actuator, one is supply and the other is a vent, so that open line you’re seeing may just be the vent. . My trucks doing the same thing. My passenger side works as is should. Driver side is not disengaging all the time and sometimes I can hear it either trying to disengage or engage and sounds a lot like a rattle. But that’s your hub and cv spline getting shredded to s**t..
Test it by applying vacuum to the larger of the two posts on the actuator. There should be a thick rubber vacuum house right under the upper ball joint, pull that off to reveal posts. Jack up the front of the truck and At 20inHg the actuator should be working and the wheel should spin freely from the CV. release vacuum and you should hear it engage and the cv and wheel should move together. If both work properly then it could be the check valve or a crack in the line. Hook the vacuum pump up to the thicker of the two lines on that rubber hose and run the truck. If you have 20-25inHg, then it’s very unlikely a leak in the vacuum lines. The lines are very brittle and will break super easy if you bend them. I just replaced the whole vacuum system on mine for $35 and it’s VERY easy. Today I bought the vacuum pump kit and I’m assuming that it’s the actuator hub on my mines that’s bad. Because I have 24inHg of vacuum when truck is running. Click to 4hi and it drops to zero, back to 2wd and goes right back up to 24. After I shut the truck off it holds 24 until I hear the check valve release then drops to zero like it should. When I apply vacuum directly to my passenger side actuator it works fine. Driver side holds the vacuum but doesn’t release the cv so I’m assuming it’s siezed together or just went bad. Very easy system to test if you have a vacuum pump and knowledge of how the system works.

 

I had a similar issue a few years ago. My left front hub would partially engage sometimes. Whenever it started making noise I could engage the switch and the noise would stop. First checked all my lines at the hubs and everything all the way back to the vacuum canister. Turns out my canister was cracked and not holding vacuum like it should. Replaced that and no more issues.