[Aiden]

I own a 2007 bmw 328i and have ben having this issue where my aux wont work. I have never been able to get it to work either. I have already tried to replace the aux and usb module but none of that works. I noticed that those cords that connect that module to the aux are connected to the bluetooth module, the bluetooth module is also broken. does anyone know a way to fix this?

[ctuna]

Is this car new to you ?
Did it ever work?

Use Mdecoder.com to see which options the car came with.

What was the name of the module you replaced.
in 2007 usb was just introduced with the Mulf 2 Hi module.
however that year often came with both a TCU and a Mulf 2 hi .
The Mulf 2 hi is under the TCU.

http://www.e90post.com/forums/showthread.php?t=1181654

[sam9116]

Originally Posted by Aiden

I own a 2007 bmw 328i and have ben having this issue where my aux wont work. I have never been able to get it to work either. I have already tried to replace the aux and usb module but none of that works. I noticed that those cords that connect that module to the aux are connected to the bluetooth module, the bluetooth module is also broken. does anyone know a way to fix this?

if you have USB audio (aka a usb port next to your aux) your aux input is handled by the MULF unit instead of directly being handled by the radio

if your bluetooth module (I would assume is TCU) isn't working, yes it indeed will prevent the aux from working as well

MULF that handles audio/usb could also go bad itself

basically:
TCU bad MULF good => no aux
TCU good MULF bad => no aux
TCU bad MULF bad => no aux

your options for fixing this is
if TCU bad:

1. replace TCU with used, recode replacement TCU, keep bluetooth, get back aux (slightly expensive, depends on if you get a shop to recode the module or DIY)
2. replace TCU with most bypass loop, give up bluetooth, get back aux (cheap)

if MULF bad:
replace MULF with used, get back aux
(you cannot bypass this module because it directly handles aux input)