So i just ran into some problems over the last few days. I bought my 05 fx4 about two months ago. The 4wd lights have never come on when turning the switch to engage them. They are on at startup though, so i know they work. I thought that they did engage though, but it turns out i think they may have always been engaged. I heard a rattle a couple of days ago, brought it in and had it looked over. Turns out i needed new actuators on both left and right side of the front end. $800 later, got those replaced and they said 4wd was good to go. Get out to parking lot, lights still don’t come on. Got home and realized it wasn’t working. So i replaced the IWE vacuum solenoid behind the battery. There is a pull on the vacuum hose, so i know there is vacuum at least at the solenoid. Afterwards, still no lights, and no sound or anything when turning **** to engage 4wd. I’m supposed to take it back in Monday, but just would like some answers or ideas.

Any help at all?

 

Update, i ended up pounding on the transfer case motor and boom. The lights are on, and it now switches and engages. I haven’t heard it engage before and never saw the lights, so this is nice. Still have a question though: the mechanic i took it to who replaced the actuators on the front end, said it was in 4wd all the time and i assumed that is why it broke. Was it just in 4wd after the actuator broke? Or what? Was it just a coincidence that the actuator broke and it wasn’t engaging in 4wd? Or is that related?

 

The ABSENCE of vacuum on the hubs locks them. Running with the hubs locked in 2wd won't hurt anything except your gas mileage.

 

Right! I get that... i think.! I’m just mostly wondering if my IWE had to be replaced because of the problem with the transfer case motor. Or if that was unrelated. It seems too similar to be unrelated. But who knows.

 

Unrelated. 2 separate things happen when you turn the **** from 2wd to 4wd - the solenoid dumps vacuum out of the IWE system to lock the hubs, and the transfer case motor moves to engage the front driveshaft.