I've had a noise coming from the front of the truck between 25 and 45 mph. At other speeds the truck is very quite. The sound is like the tires are cupped, but the tires are brand new. While at the dealer for the transmission filter and oil to be changed I asked them to look at the noise. The dealer sent me a picture showing the vacuum line to the IWE's has been chewed thru. Which I would not doubt since there's a lot of mice where I live. What do the IWE's do and how does a vacuum line affect them?

On another note they also found the left and right side manifold bolts broken, which luckily are cover under the Premium Care Warranty.

Thank you

Greg
2016 Lariat Crew, FX4, 3.5

 

So, IWEs are what locks your front wheels when you are in 4WD. So here is what happens:

1. You switch to 4H.
2. Transfer case engages and bring the front diff and front shafts to match the speed that you are going.
3. A solenoid releases vacuum and thus engages the IWEs to lock the front wheels.
4. You switch back to 2H.
5. Solenoid applies vacuum and this disengages the IWEs to unlock the front wheels.
6. Transfer case disengages.

Hope that answers your question.

 

IWE = Integrated Wheel End

 

IWE is basically an automatic front hub. They are controlled by vacuum. Vacuum applied unlocks, so they are "normally locked".

 

I believe you meant "unlocked" in what I bolded.

 

Thank you for the info

 

I think it depends on terminology. The "normally open" or closed from a technical perspective means without any input, what is the status or function. Such as a normally open relay.

Without vacuum applied they are locked.
I didn't mean normally as in normal use driving in 2wd.

​​​​Apologies if that wording was not clear...