So I'm driving 5 hours south this weekend to pickup my new to me f150.the return trip will possibly be through some nasty mountain passes (depending on the weather and road conditions). I know the 4x4 works on the truck but wanted some clarification on bypassing the iwe system just in case.

From what I have read, it is my understanding that if I unplug engine vacuum to the solenoid, my hubs will remain locked. In this scenario, the 4x4 will still engaged when I throw the switch right, it will just leave the front cv shafts spinning in 2wd mode as well?

It's sub zero temps where I'm picking it up, and I don't want to be testing the system with my vacuum tool till I get it safely home and in the garage. Other than a slight mileage penalty, leaving the hubs locked (but transfer case in 2wd mode) won't be harmful to the truck right? And I can still engage and disengage 4x4 on the fly?

This would essentially make the truck operate like a Chevy or dodge which have the shafts locked to the hubs all the time as well right? I just want to be sure I'm understanding the system correctly. Let me know what you think. Thanks?!

Also, just out of curiosity, when the solenoid fails, does it typically fail in the open position (engine vacuum allowed resulting in hubs trying to stay unlocked), or closed (no engine vacuum allowed, hubs locked all the time)?

 

Yes on the first statement but you will need to cap the solenoid on the IWE side. And it fails locked into 4x4 second option.

 

This is asuming that the T-case is working properly also...when you flip the switch to 4H...the T-case needs to work too, if not your stuck with locked hubs and no 4WD.