Hello everybody. This is the first time posting in a forum like this, usually I can find my answers by using the search tool (which I have done for hours now to no avail) I am desperately trying to find the Bluetooth module in my A4. I found some YouTube videos saying it was under the floor, it's not. I called two different dealerships and both said it was behind the glove box, it's not. Please if anyone knows where the Bluetooth module is located in a 2011 A4 premium Plus I would really appreciate any knowledge or help. Thanks in advance.

 

Does your Premium Plus have MMI or the Concert/Symphony radio ? For radio applications, the BT module -R36- is supposed to be located under the carpet under the front right (passenger) seat. Otherwise, BT is part of the MMI main unit -J794-.

 

It does have mmi it's one lower than the b/w stereo. And I pulled up the floor where all the other vehicles showed the modules to be. But not on my A4. I'm waiting for the removal tools to check the center though. Thank you for your response. It is much appreciated.

 

The next question, then, is why do you need to find the BT module? Is BT not working properly? Is the software up-to-date on your MMI main unit? Do you have access to the MMI Green Engineering menu? --g

 

As already pointed out, if you have MMI 3G navigation plus (controls around shifter) rather than the Concert head unit, the Bluetooth components are fully integrated into the MMI 3G controller J794, which is that object in the dash with the disc and SD card slots. Which front end you have is independent of which back end (standard sound system with 10 speakers vs. B&O sound system with 14 speakers) you have.

 

Well. My MMI gives me about 20 seconds of use before completely freezing. I can get to most things by then and then it just stops completely. The reason I'm trying to get to the Bluetooth module is because my MMI only freezes when the Bluetooth symbol appears on the bottom of the screen. I already bought the optical loop to bypass the module as I really don't want it / need it in the first place. Id like to just get some tunes back without having to hard reboot the MMI everytime I want to change the volume or radio station to get my first 20 seconds of use before it freezes.

 

Troubleshooting the J794 is a royal pita because it's basically a mini computer with many ins and outs and components, and no worthwhile diagnostic methods. It actually has a boot interface if you solder in an interface to wire to. It also has a hard drive in it that isn't unprone to eventually dying.

The problem with the MOST bus (the optical bus) is you cannot bypass the J794. It is the ring master, without it there is no ring. And Audi, with their typical foresight, provides no other means of communication to the J794 except over the MOST bus. So if there's an issue with it, such as some other ring device, the J794 can no longer be interacted with for diagnostics. There is the ring break concept, but I've been very unimpressed by it so far. And not having a CAN connection to the J794 is just being excessively cheap on Audi's part.

If you have MMI 3G and the standard sound system, you only have two MOST bus devices besides the J794. So it's really not that much to bypass the radio and then the J533 (remove glove box, it's behind it to the left with the big red plug on it) to see if the J794 stays up. But I can't confirm the J794 won't shut down if it cannot communicate with the J533. I don't have MMI 3G to play around with at that "what about this, what about that" level. That also doesn't isolate the MOST cabling. You'd need the other type of bypass plug (male vs female) that you could plug into the J794 so it has an up bus but with no cabling or members to really isolate.

There's no reason to presume the presence of the Bluetooth icon makes it a cause. It could be the J794 inits the Bluetooth and throws up the icon, moves on to the next process, dies. An actual interface to the boot messages would tell you exactly what the problem is, but Audi decided customers are not entitled to that kind of reliability.

But try what you can to validate the MOST bus; it very well could be a radio unit issue.

 

Man. That's super informative and depressing all at the same time. You're right. I don't want to assume it's the Bluetooth but I figured If that wasn't it I was just SOL and it looks like I probably am anyway. Guess I go back to an aftermarket amp to the speakers in the trunk with a Bluetooth adapter and bypass the MMI completely. I don't see what other choices I really have. Thank you very much for all of the awesome knowledge.
​​​​​​