First of all, I've read numerous IWE threads from start to finish looking for the answer to my problem. Therefore, my inability to find the solution to my problem isn't due to a lack of research.
Secondly, I'm reasonably mechanically inclined as I rebuilt the trans in my 05 5.4 SCrew (104K miles) about a year and a half ago and its still running great. Now that that's out of the way, one day (since rebuilding my trans) my 4wd worked perfectly, the next time nothing...ie, truck's running, in park, drive, neutral...etc, I turn the switch and no lights come on, no noise from the xfer case (no clunk)...nothing. I've had the IWE solenoid replaced with the one with the 'rain shield' on it, I've pulled the 4wd actuator motor and tested it with 12v (moves flawlessly), I've rechecked the IWE solenoid with voltage, and checked resistance (to make sure the electromagnet that makes it function wasn't blown), I've checked for vac and leaks...aside from the vac pump method, I've pulled the switch and shorted across the pins in case the switch was bad, I've checked all associated fuses, checked the connectors at the "GEM" and of course the xfer case actuator motor. In a fit of desperation, I even disconnected the ground on my battery for 10-15 minutes in hopes that (as I read somewhere a guy "fixed" or "reset" his this way) something would be reset.
I've read somewhere that the system "waits" for a signal from the IWEs to tell it to engage the xfer case actuator, yet I have also read that they operate independently. ANY AND ALL HELP AND ADVISE ARE GREATLY APPRECIATED AS I AM NOW STUMPED. Sorry this question is so long, but thanks for reading.

Jeremy

Oh, and anyone that wants the 500+ page factory service/repair manual for the trans, I can probably scan it and make it available.

 

Did you replace the check valve off the solenoid when you replaced the solenoid? Its part of the vacuum line and seems to trap moisture and screw with the vacuum signal (but most test pull enough to move the moisture that isnt moved during normal operation). Its located about 6-8" off the solenoid. Mine plugs up a couple times each winter and always causes the iwe's to get stuck between 2wd/4wd

 

I did not replace it, but it seemed to be functioning correctly when I checked it...ie, allows flow in one direction and none in the other. Should i replace it anyway?

 

I would put the front of the truck on jackstands and try to engage 4wd. If when in park you can spin the front driveshaft the problem must be in the transfer case. Just because your shift motor works off the truck does not mean it works with resistance on it. If the front driveshaft turns and you still dont think its a shift motor problem I would check to make sure the voltage is being sent to the motor. This may require another set of hands so buy a 12 pack and enlist the help of your neighbor.

 

Also for what its worth, I had two bad check valves, faulty iwe solenoid, a rubbed through portion of vacuum line about 16" from where it plugs into the left wheel, and a stuck transfer case shift motor. All is well now and im ready for the harsh winter they are predicting...

 

Long shot, but check the selector switch yet?

 

Mlkx4, I'll give that a shot, Thanks.

GatorB8, yes, I checked the switch by shorting across the pins to take the switch out of the loop.

Side note, I had a flywheel crap out on me. It was after the flywheel that I noticed it not working, but all of my connectors are of course connected. The wiring harness that runs over the bell housing has 4wd related "stuff" in it, if I'm not mistaken. Is it possible I cut a wire in that harness? Looks like I'm breaking out the multimeter and chasing wires as well.