I have read every 4x4 related thread I can find and I still need some help. I have an 05 fx4 and the 4wd stopped working a couple weeks ago and about left me stuck on a boat ramp! When I turn the **** nothing happens, no lights come on, no sounds, etc. I tried the "knock the transfer case motor with a hammer" trick and that did nothing. I was thinking that it was probably the transfer case shift motor but from other threads that I've read when it goes bad there should be a code that pops up but nothing showed up when I scanned it. I have a cheap scanner so should I take it to a shop and have them scan it, maybe their scanner works better?? If the motor is not running but the key is on and I turn the 4x4 **** I can hear some clicking, which I assumed must be then solenoid or something which to me is more of a case against the shift motor. I also checked all fuses that were related to 4wd system and all were ok.

I tried reading about the whole IWE system as well and I lifted up the front end and confirmed that when I shift into 4wd the front driveshaft is not turning and the hubs are not locking in either. When I turn the tires the half shafts do not turn either so I take that to mean the IWE is not engaging at all. I'm by no means a mechanic of any kind as you can probably already tell, but I'm not afraid to tackle stuff on my own and I'd be more than grateful if somebody with more experience can give me their thoughts. Thanks, Matt

 

Have you checked to see if the front driveshaft will move when you engage 4wd? If it locks in place, then the shift motor is fine.

 

Yeah that was one of the first things I checked, it is not moving when I shift into 4wd. The dash light does not come on, shift motor makes no noise, nothing happens at all that I can tell

 

Have you checked to see if the shift motor is getting power? If it is, then it may be shot. The "smacking with a hammer test" isn't always accurate.

 

and you have not replaced you IWE Solenoid yet ?

 

No not yet, should I do that first? I thought if the IWE solenoid was bad then the front hubs would be locked in all the time right? I am still getting vacuum at the front tires which I took to mean the IWE is still working. Or is it that if the IWE solenoid goes bad it just won't release the vacuum and lock in the hubs??... Regardless, when I switch to 4x4 high tge shift motor is not doing anything and the front driveshaft is not turning so I thought the issue was either electrical and the shift motor was not getting any power or it was just dead. Please correct me if my line of thinking is wrong

 

No and that is one of the biggest questions I have, is there a way to test this?

 

Maybe not very accurate, but therapeutic -- at least to the one wielding the hammer.

 

Haha, fair enough.

 

Turn the key on, and measure the voltage from each of the wires going to the shift motor. Then switch it to 4hi (or 4lo). If a wire that didn't have voltage suddenly does, you're getting power. If there is still no voltage, then it's not getting power.
I don't have a wiring diagram, so I can't tell you which wire is supposed to do what. You may be able to find one online though.