martinspangler

My 4x4 does not work. When running, the 4x4 switch works. Light comes on dashboard. Very faint click sound. After diagnosis, and engine off, jacked up one side and the wheel and half shaft turned. Checked vacuum lines on both sides and pulled them off. No sound of vacuum release. Jacked up other side and wheel turns but half shaft does not. TC goes into 4WL. Front drive shaft locks up when supposed to. I have no engine codes on my reader. Best I can tell, I have no vacuum going to either IWE, but one is locked to the shaft and the other isn't. Anyone know if this is the solenoid or a bad IWE on one side. I can't seem to get a positive diagnosis for any particular part.

jamie930

When the 4WD is on you should have NO vacuum. NO vacuum engages the IWE.

With the engine off both IWEs should be engage since you need the engine vacuum to disengage the IWE

Check with the front wheel off the ground with engine off the front driveshaft should turn then check with engine on driveshaft should NOT turn

If one IWE is not engaging this is why you have no 4WD seeing how the front is a open diff

martinspangler

Thanks for the awesome reply! OK, I rechecked. When the 4x4 switch is on there is no vacuum. When the switch is in 2WD, there is no vacuum. With the engine off, only the driver side IWE is engaged. With DS front wheel off ground and engine off, the front half shaft rotates with the wheel. The front drive shaft coming from the Transfer case does not rotate with the wheel and half shaft when turned. With the passenger side front wheel off the ground and the engine off, the wheel turns, but the half shaft does not and the front drive shaft from the transfer case does not. With engine on, the front drive shaft attached to the transfer case does not turn. The transfer case will go into 4WL. The light on the dashboard reads 4WH and 4WL (respectively per position) and the front drive shaft from the transfer case turns when driving. No pull from the front wheels. Vacuum lines checked and attached to IWE properly at wheels on both sides. Could it just be the solenoid, or possibly the vacuum hub attached to the IWE on the passenger side? Or both, or the whole IWE is bad on the PS? Thank you again for your help!

60DRB

"With the passenger side front wheel off the ground and the engine off, the wheel turns, but the half shaft does not."

Sounds like the passenger side IWE is broken/stuck disengaged. My PS IWE was broken when I bought my truck, but in the engaged position. There's a spring inside as well as the vacuum diaphragm. The spring is likely the culprit.

How to replace...

http://www.f150online.com/forums/2004-2008-f-150/360269-iwes-removal-replacing.html
Tools needed are in that link too. Not very hard to do.