[Wind90]

Hello everyone.
I have a 2010 E90 328i. I've encountered an issue where my Aux port works inconsistently. For example, it may work fine for three days, and then for several days it doesn't work. Or it might work fine today, but after I go to the store, turn off the car, and return, it stops working. When it works, it works perfect without any interruptions, so I don't think the issue is with the cable, the port, or the wiring.

When it doesn't work, there’s no checkmark left to it. Normally, when it’s working, I can see a checkmark to the left of the AUX label on the screen. Also, the volume is locked near zero. Additionally, I noticed that when I turn on the ignition, and it’s a “lucky day,” above the “Aux front” text, where the USB label is, I see a "initializing" message for a few seconds, and only after that does it change to “Not Connected.” On an “unlucky day” when the aux isn’t going to work, the screen immediately shows “Not Connected” without the initialization.

I've read some forum threads on similar issues, and some people found the problem to be with the MULF or MULF2 module. But the thing is, I don’t have this module. In the trunk, where the MULF should be, I have another module called TCU. Could it be causing the issue? Meanwhile, Bluetooth and radio and CD is working consistently and without any problems.

Thanks for reading and hepling.

Video:
https://www.youtube.com/shorts/xrAT0mmXauc

[ctuna]

Mulf2 module will be under the TCU in that year car.
That's a TCU 1.5 that you have displayed in the picture.

Aux port source maybe dependent on options installed .

And or head unit .

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

[Wind90]

Originally Posted by ctuna

Mulf2 module will be under the TCU in that year car.
That's a TCU 1.5 that you have displayed in the picture.

Aux port source maybe dependent on options installed .

And or head unit .

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

I'm not sure where to check the installed options, maybe in this photo.

And yes, the MULF module turned out to be located under the TCU module.
My head unit is CIC, if that's what you mean.
Maybe I should try installing a different MULF module? Do I need to reprogram anything when replacing it?

[ctuna]

Did you try running the Mdecoder.com vin decoder.
(this should give you the installed option numbers)
Do you have a center console USB connector?(suggests 6fl option )
Did you read the Link about TCU and Mulf?(read entry 4 in the supplied link from earlier)
Most of the time replaced module require programming unless they came out of a car
with exactly the same configuration.

There are several versions of the Mulf , Mulf 2 high is the best one see the link .(because it supports USB)

If you are going to do your own DIY's I would suggest you get
a Diagnostic setup consisting of a K/D can cable and
BMW Standard Tools and Ista D.
Finding the Free downloads for these can be more difficult but not impossible
use the coding sub forum and Idrive sub forum .

diagnostic manual ista/inpa
https://www.google.com/url?sa=t&rct=...xo19teM9vkTF-C
https://www.google.com/url?sa=t&rct=...7x8H3pN8h1fMuF
https://bimmerprofs.com/diagnostics-inpa-part-1/
https://www.google.com/url?sa=t&rct=...lkXEhlQYy4i9Nb
https://www.bimmerforums.com/forum/s...-P-actually-do
https://www.bimmerfest.com/forums/at...1&d=1590283589
https://www.google.com/url?sa=t&rct=...kBbC27TJLX3BGe
https://www.google.com/url?sa=t&rct=...WekqhcC6hsgK2c
https://www.e90post.com/forums/showthread.php?t=1649066
primary links
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.nathansbmwworkshop.com/b...or-dean-videos
ista problems
https://www.e90post.com/forums/showthread.php?t=1661945
https://www.e90post.com/forums/showthread.php?t=1581663
https://www.bimmerfest.com/threads/t...-pdfs.1449540/

This guy has similar issues

https://www.e90post.com/forums/showthread.php?t=2142421

[Wind90]

Originally Posted by ctuna

Did you try running the Mdecoder.com vin decoder.
(this should give you the installed option numbers)
Do you have a center console USB connector?(suggests 6fl option )
Did you read the Link about TCU and Mulf?(read entry 4 in the supplied link from earlier)
Most of the time replaced module require programming unless they came out of a car
with exactly the same configuration.

There are several versions of the Mulf , Mulf 2 high is the best one see the link .(because it supports USB)

If you are going to do your own DIY's I would suggest you get
a Diagnostic setup consisting of a K/D can cable and
BMW Standard Tools and Ista D.
Finding the Free downloads for these can be more difficult but not impossible
use the coding sub forum and Idrive sub forum .

diagnostic manual ista/inpa
https://www.google.com/url?sa=t&rct=...xo19teM9vkTF-C
https://www.google.com/url?sa=t&rct=...7x8H3pN8h1fMuF
https://bimmerprofs.com/diagnostics-inpa-part-1/
https://www.google.com/url?sa=t&rct=...lkXEhlQYy4i9Nb
https://www.bimmerforums.com/forum/s...-P-actually-do
https://www.bimmerfest.com/forums/at...1&d=1590283589
https://www.google.com/url?sa=t&rct=...kBbC27TJLX3BGe
https://www.google.com/url?sa=t&rct=...WekqhcC6hsgK2c
https://www.e90post.com/forums/showthread.php?t=1649066
primary links
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.nathansbmwworkshop.com/b...or-dean-videos
ista problems
https://www.e90post.com/forums/showthread.php?t=1661945
https://www.e90post.com/forums/showthread.php?t=1581663
https://www.bimmerfest.com/threads/t...-pdfs.1449540/

This guy has similar issues

https://www.e90post.com/forums/showthread.php?t=2142421

No, this is the first time I've heard of Mdecoder
I have a usb port next to the aux port, and second usb port in the glove box
I read your link, but I'm having a little trouble figuring out which wires need to be reconnected
Thanks for all your links, I appreciate it
I most likely have MULF2 High
Today my aux stopped working again, I went to the trunk, unscrewed the module, disconnected the power and the blue large connector then reconnected and the start working
I checked the wires and connectors, everything looks fine, no wires broken off

[ctuna]

this doesn't sound like a problem with wires being disconnected.
In an case you need to understand which options the car came with
that is where mdecoder comes in .
It's easy to run it you just plug your Vin in and gives you back the installed
options.

I would try checking the battery voltage which must be above 12.4 first.
When the battery is low it can cause all kinds of phantom problems .
Measure it with a Voltmeter.
Then reseat the connectors at the Mulf 2 Hi .

[Wind90]

Originally Posted by ctuna

this doesn't sound like a problem with wires being disconnected.
In an case you need to understand which options the car came with
that is where mdecoder comes in .
It's easy to run it you just plug your Vin in and gives you back the installed
options.

I would try checking the battery voltage which must be above 12.4 first.
When the battery is low it can cause all kinds of phantom problems .
Measure it with a Voltmeter.
Then reseat the connectors at the Mulf 2 Hi .

Here are my options
https://www.mdecoder.com/decode/wbaph7g5xanm48135
Also today I went to the store with a working aux and when I got back the aux was not working. I went to the trunk, measured the voltage, it was 12.48 volts, car was shut off. I unscrewed the module again, disconnected the power and reconnected. And the aux worked again
When I got home, the aux was still working, the voltage was 12.41.

[ctuna]

I worked in Electronics for years and Connectors are a bigger issue
than actual component failure. So many times I fixed the problem
by reseating the board or connectors or had actual bad connectors.
Unsatisfying to fix stuff this way but it saves you a lot of anguish.

Battery Voltage is good it's good that you checked it.
I put my car on a Ctek battery tender twice a month .
Charge the battery and measure the voltage then measure it again in the morning
or however long you let the car set to see if the battery can hold a
charge or if there is a significant drain.

[Wind90]

Originally Posted by ctuna

I worked in Electronics for years and Connectors are a bigger issue
than actual component failure. So many times I fixed the problem
by reseating the board or connectors or had actual bad connectors.
Unsatisfying to fix stuff this way but it saves you a lot of anguish.

Battery Voltage is good it's good that you checked it.
I put my car on a Ctek battery tender twice a month .
Charge the battery and measure the voltage then measure it again in the morning
or however long you let the car set to see if the battery can hold a
charge or if there is a significant drain.

Next time I'll try wiggling the connectors instead of reconnecting them
So if it's bad connectors, it will probably make the aux work again
If not, then I don't know. Make a button in the cabin that cuts the power to the MULF, so I can restart the module every time it doesn't work? XD

[ctuna]

If the reseat doesn't work and you can't see anything wrong with the connectors and your battery is stable it's probably time to think about another module.