I have a 2006 Mazda 3 and in the center armrest, there's a small silver switch and a cord that could connect to my iPhone. Is this a built in AUX or something? I have no idea what it is... can someone help

 

The 2006 didn't have a built in input, so no it isn't stock.

I'm guessing if you were to follow the wires you'd find it goes to a wired FM modulator. Basically a little box plugs inline with the stereo's FM antenna, and when powered (ala the switch) it turns off the FM signal and receives the wired signal from your device as if it were the radio signal.

It may require your stereo be on a specific frequency, usually 88.1 or somewhere there abouts. I'd pull the stereo and see if there is in fact a modulator plugged into the antenna wire. If so it may have information about the frequency printed on the case.

 

Thanks for the reply icspots! I'm not really.. well handy with cars and such, but I'm doing my best to google everything I'm told lol O_O I tried flipping the silver switch a few times and the radio was on the entire time and never turned off =/ I'll try to follow the wire to see where it goes, though I'll probably have to google/youtube to see how to do so

 

It's also possible the modulator isn't hooked up..... or potentially the previous owner removed the modulator but left the switch. Without looking into the console it's all just guess work. Or it could have been for something else and I'm just shooting in the dark.

Pulling the HU is super easy and will take only five minutes or so and a phillips head screwdriver.

-open the glove box
-grab the dash strip and pull to release the tension clips.
-don't pull the far right of the strip straight out as it has a hook.... either release all the clips and slide it out, or release the several right of the LCD and gently bend the strip to clear the hook
-remove the two phillips head screws by the LCD (the other two are for the upper dash piece)
-grab the HU (not the faceplate) and pull to release the clips

Be careful, the HU is heavy and if you're not careful you can scratch the dash with the sides of the frame once you have it out. If you're fully removing it then unplug the harness and antenna wire and set it aside. If you're just glancing around then keep an eye on it to make sure you don't ding things up.

You can also pull the cupholder and gear shift surround and see if the wires go anywhere obvious.
-open the center console
-set the parking brake
-grab the front edge of the center console compt and pull up to remove the cupholder
-guide the cupholders around the brake handle, if they stay connected to the gear surround you can just pop them loose
-if MTX unscrew shift ****, otherwise grab shifter surround and pull up to release.

To remove ashtray:
-remove two phillips head screws revealed from under the shift surround
-remove lighter insert
-grab ashtray/lighter module (helps to stick your right thumb into the lighter socket so make sure the ignition is off!!!!!) and pull back to release the clips
-unplug the several bulbs/wires and set aside.