So I drive a 2009 F150 platinum FX4 with the 5.4. I知 trying to figure out why I知 getting vacuum to the IWE vacuum lines at the start of them but I知 not getting any vacuum at the end of the lines, I have taken the check valve off. Either way I get nothing. Just to find out, I unhooked the vacuum lines and put the truck into 4 high and the passenger wheel engages but the driver side doesn稚. Also, in 2wd with the truck running AND with the truck off, the passenger side turns the cab axle and the driver side does not. ANY help is appreciated.

 

If you have vacuum to only one wheel the 2 causes I can think of is
1) weak vacuum
2) clogged hose

With that, I suspect the driver side is shorter and would use up all the vacuum, making the passenger side weak. A clogged driver would definitely allow only the passenger to engage though.

Wait, I reread your comment.
Are you saying that with no vacuum connection to the IWE, you have a locked hub? If so, your IWE is damaged or stuck in the locked position. You need to also confirm for us that the passenger wheel is also locked when the switch is in 2h.
The more I decipher your message, it sounds like you have a problem with the passenger IWE.
With the truck off, the hubs should be locked, default operation is a locked state, only once vehicle starts does the vacuum disengage for 2wd operation. The suspicious part there is that the driver side is unlocked and should not be (engine off).

Look up a youtube channel FordTechMakuloco. He has a few videos explaining how the system works and how you can test the solenoid and/or the vacuum system. Does your model have 2 solenoids? Back in the the day was a 2wd solenoid and a 4wd solenoid, perhaps the 'locking' solenoid to 4wd is not working either due to a bad solenoid or electrical connection/signal.

 

Thank you for the reply. And yes, the passenger side is locked in in 2 with truck both running and shut off. I went ahead and unhooked my vacuum lines as well and ordered a whole new set to run to both sides. Gotta change out that passenger side iwe as well it sounds like. Also thanks for the referral to FTMUL. I watch a lot of his videos. Guy does a great job of explaining things.

 

If you have a vacuum pump, use it at the IWE to see if you can disengage it.... with vacuum applied, and if it disengages, you'll be able to spin the wheel separate from the half shaft.

I think you only apply 20 inches of vacuum. Too much can damage it internally.

There was a person here a while back that replaced vacuum lines -his were clogged up somehow.

 

With engine off, both IWEs should be engaged.

With engine on and in 2H, both should be disengaged.

Vacuum is required to disengage the IWEs, no vacuum state will engage them.

 

I致e got a whole new set of vacuum lines ordered because I found out they are clogged and I致e also ordered two new IWE痴. This might be off topic but could the fact that those lines are clogged be any sort of cause for my fuel mileage and power be poor? In park and at idle when I hit the gas just to rev it痴 got kind of a delayed reaction and then idles down real low before it corrects itself.

 

Sounds like a throttle body cleaning is in order, possibly plugs. But yes, mileage is potentially affected by the IWE's being engaged all the time - if the lines are clogged, they can't vacuum them apart.