What is this for?

[Armo325]

It crossed my mind to do a search but I didn't know what to search for.

 

I was under the hood today cleaning up a few things and noticed this random part and I have no idea what it is for.  I consider myself reasonably savvy when it comes to motors but this one isn't obvious to me.  In the photos below, it's in the red circle.

 

 

 

 

It basically looks like a capped off hose.  I traced it down under the motor and it joins a wire bundle that plugs in here:

 

 

I'm not exactly sure what the name of that part is except that it's attached to the front differential - it's a 4WD truck.

 

I traced that wire bundle the other way but it just joined in to bigger and bigger bundles so I stopped following it.  I expect it ends at the ECM or TCM but that's a guess.

 

Anyone know what that "capped hose" is for?  Also, it isn't secured to anything and I feel like maybe it should be zip tied somewhere.  Should it be?  The only person besides me that has been in there is the dealer.  I wouldn't be surprised if they cut something loose and didn't fix it.  Thanks in advance.

[bdbake01]

Transfer or front diff case vent. 

[SarahsGMC]

I cant see pictures for some reason

[Jsdirt]

Yep - that's the breather for the front differential. That cap is a one-way check valve to allow air to escape, but nothing to enter, so it doesn't end up full of mud and water (and salt water, if you live in the North). Actually, now that I think about it, it's probably just a cap - not a check valve. Just keeps crap from falling directly down the open hose.

 

Your last pic is of the 4x4 actuator - the vent shouldn't be going there - should be entering the top of the differential assembly.

 

Enjoy every minute of that newness - it doesn't last long!! 

[Armo325]

6 minutes ago, Jsdirt said:

Yep - that's the breather for the front differential. That cap is a one-way check valve to allow air to escape, but nothing to enter, so it doesn't end up full of mud and water (and salt water, if you live in the North).

 

Your last pic is of the 4x4 actuator - the vent shouldn't be going there - should be entering the top of the differential assembly.

Good to know.  Thanks!  I'll have to see if I can figure out where it's supposed to be from the factory and put it back in place.  Thanks again.

[Armo325]

8 minutes ago, Jsdirt said:

Enjoy every minute of that newness - it doesn't last long!! 

 

I couldn't agree more.

[Armo325]

On 6/11/2018 at 7:01 PM, Jsdirt said:

Your last pic is of the 4x4 actuator - the vent shouldn't be going there - should be entering the top of the differential assembly.

On that note, if anyone has a minute and a 4WD, would you mind taking a quick photo of where the diff vent tube is sitting inside your engine compartment?  I have a sneaking suspicion the dealer moved it to do something and didn't put it back.  I just want to make sure it isn't supposed to be zip-tied or otherwise secured to something.  Thanks in advance.

[Jsdirt]

I would, but I have a 2007 - doubt that will be of any use.

[Old School Mechanic]

I noticed the same on my 2015...mine is taped, yes I said taped, to the white thing that is zip tied to the wiring harness.

You would think they could find a better place for it and secure it a little more professionally.