Part/Function Identification / 2010 GMC Yukon SLT

I'm installing an aftermarket headunit and while burrowing around in the vehicle trying to understand wiring, etc I came across a few things that I was hoping this forum could help me with. They don't have anything to do with my install, these are just curiosities...

First - in the back rear interior quarterpanel trim, there is a small plastic grille toward the front of the vehicle and a large plastic grille toward the back with the cigarette lighter port (pic 1 below):


If you look in the small plastic grille, you'll see this (best pic I could get, "pic 2" below):


If you take the cover (?) thing off on the top side (pic 3) and look inside, there's a wire that runs in there from that (pic 4) back toward the back of the vehicle where it looks like it connects to something else (pic 5):

PIC 3:


PIC 4 (inside trim, looking toward the mystery part):


PIC 5 (inside trim, looking toward the back of the car):


Any ideas as to what that is? Also what is the rear (larger) grille for?


Secondly, what are these holes for to the left (driver side) of the console? Looks like it's for a microphone or something like that but obviously the mic is up in the headliner...



Like I said these are just curiosities but I can't seem to figure them out via google or looking at the parts fiche...

I may have a couple of headunit install questions that I'm working through but that will come later when/if I realize I need it...

First one looks like an air temp sensor for automatic HVAC.

Fless said:

First one looks like an air temp sensor for automatic HVAC.

Click to expand...

Ah that makes sense! Googling around finds this: https://shop.advanceautoparts.com/p...ct-air-temperature-sensor-15-5632/18056635-P#

Fless said:

First one looks like an air temp sensor for automatic HVAC.

Click to expand...

Would that be the rear HVAC unit, with the air intake being the smaller front grate, and the air output being the larger grate?

The passenger rear panel has the rear hvac unit behind it, the little sensor poking into the air duct is a thermistor to determine the air temp.
the small holes in the drivers side of the center console is nothing just air holes

Doubeleive said:

The passenger rear panel has the rear hvac unit behind it, the little sensor poking into the air duct is a thermistor to determine the air temp.
the small holes in the drivers side of the center console is nothing just air holes

Click to expand...

Interesting - I had no idea there was a separate unit back there. TIL

Such a strange thing to put random air holes though? I wouldn't think that little bit makes any difference with regard to letting that area breathe? But maybe it does...

Anyway - appreciate the help!

Joseph Garcia said:

Would that be the rear HVAC unit, with the air intake being the smaller front grate, and the air output being the larger grate?

Click to expand...

On my NBS the air comes out of the front grate.

rrrnnn said:

but obviously the mic is up in the headliner...

Click to expand...

Are you sure that what you think is the microphone isn't the aspirator for your A/C temp control?

The holes in the side of the center console are for a microphone of sorts. On some of the trucks (Escalade, Denali) they have an ambient/road noise sensor for noise canceling. It is called ANC (active noise canceling).

The "microphone" in the headliner is actually an air temperature sensor with a little fan in it. When you set the temperature on the dash it senses the air temperature in cabin and controls the temperature automatically.

There is also another air sensor in the rear headliner.

kbuskill said:

The holes in the side of the center console are for a microphone of sorts. On some of the trucks (Escalade, Denali) they have an ambient/road noise sensor for noise canceling. It is called ANC (active noise canceling).

The "microphone" in the headliner is actually an air temperature sensor with a little fan in it. When you set the temperature on the dash it senses the air temperature in cabin and controls the temperature automatically.

There is also another air sensor in the rear headliner.

Click to expand...

The ANC mic's on my Denali are in the headliner and look just like the ambient air sensor or very similar anyway.