I've been stuck on fixing this radio for the past 4-5 months, and still no luck. So far my issue is the Screen not working at all (No Splash Screen Pop-Up), and none of the MMI Controller buttons light up (Besides the E-Brake obviously.) I've looped out each individual component in the rear of the car (even the Bluetooth module under the driver seat), and nothing seems to enable the screen to pop up. I don't have access to VCDS, and I'm not sure if spending 200$ is worth this old radio. All the components seem to be getting the red optical light, so my theory is either the Screen or the J523 aren't receiving power, or are just dead modules. Here's a scan from my OBDEleven scanner from a few months back. No signs of any communication to any of the radio components. (For context this scan was taken when there was a fuse in the passenger side fuse box labeled "communication" draining the battery, which gives life to the optical cables in the back of the car) (Also Fixed the "tyre pressure monitoring" there was a missing fuse")

Any help would be greatly appreciated.

OBDeleven vehicle history log
Date: 2023-10-27 14:27:15
Car: Audi
Year: 2006
Body type: UNKNOWN
Engine: kW ( hp) l
Mileage: UNKNOWN

---------------------------------------------------------------
Full scan
Control Units: 20
Fault count: 26
Control Units:
72 Rear Right Door
System description: TSG HR H21
Software number: 4F0910795E
Software version: 0050
Hardware number: 4F0959794E

Faults:
No trouble codes found

78 Sliding Door Right
System description: TSG HR H21
Software number: 4F0910795E
Software version: 0050
Hardware number: 4F0959794E

Faults:
No trouble codes found

52 Passenger Door
System description: TSG BF H12
Software number: 4F0910793E
Software version: 0120
Hardware number: 4F0959792E

Faults:
No trouble codes found

62 Rear Left Door
System description: TSG HL H21
Software number: 4F0910795E
Software version: 0050
Hardware number: 4F0959795E

Faults:
No trouble codes found

55 Headlight Regulation
System description: AFS 1 H01
Software number: 4F0910357E
Software version: 0010
Hardware number: 4F0907357E

Faults:
No trouble codes found

17 Dashboard
System description: KOMBIINSTR. M73 H17
Software number: 4F0910930A
Software version: 0660
Hardware number: 4F0920980N
Hardware version: H17ÿ

08 Air Conditioning
System description: KLIMABETAETIGUNGH12
Software number: 4F0910043
Software version: 0170
Hardware number: 4F1820043S

Faults:
No trouble codes found

19 Gateway
System description: Gateway H11
Software number: 4F0910468A
Software version: 0070
Hardware number: 4F0907468D

Faults:
00384 - Optical data bus
static

01325 - Tire Pressure Monitoring Control Module
static


91 Engine
System description: ESP 8.0 quattro H05
Software number: 4F0910517L
Software version: 0090
Hardware number: 4F0614517L
Hardware version:

Faults:
01826 - Steering angle sensor, voltage supply terminal 30
Intermittent


00493 - ESP-Sensor unit
Intermittent



4F Central Electrics 2
System description: ILM Beifahrer H10
Software number: 4F0910280
Software version: 0080
Hardware number: 4F0907280B
Hardware version: ---

Faults:
00446 - Function limitation due to insufficient voltage
Intermittent



15 Airbag
System description: 66 AIRBAG AUDI8RH29
Software number: 4F0910655F
Software version: 0300
Hardware number: 4F0959655A

Faults:
02095 - Component protection active
Intermittent


00532 - Supply voltage
Intermittent
03 Brakes
System description: ESP 8.0 quattro H05
Software number: 4F0910517L
Software version: 0090
Hardware number: 4F0614517L
Hardware version:

Faults:
01826 - Steering angle sensor, voltage supply terminal 30
Intermittent


00493 - ESP-Sensor unit
Intermittent



16 Steering Column
System description: J0527
Software number: 4F0910549A
Software version: 0410
Hardware number: 4F0953549C

Faults:
00446 - Function limitation due to insufficient voltage
Intermittent


00532 - Supply voltage
Intermittent



01 Engine
System description: 3.2l V6 FSI
Software number: 4F1910559E
Software version: 0070
Hardware number: 4F1907559A

Faults:
P160200 - Power supply terminal 30
Voltage too low
Intermittent


P165300 - Read DTC memory of
ABS CM
Intermittent


P253300 - Ignition Switch Run/ Start Position Curciut
Intermittent


P307300 - Fuel pump
Electrical error in circuit
Intermittent
02 Transmission
System description: AG6 09L 3.2 FSI USA
Software number: 4F2910156D
Software version: 0020
Hardware number: 09L927156A

Faults:
P090500 - Gate Select Position Circuit
Range/Performance
static



05 Keyless System
System description: FBSAUDIC6 ELV H31
Software number: 4F0910852
Software version: 0210
Hardware number: 4F0905852B
Hardware version: 242ÿ

Faults:
00446 - Function limitation due to insufficient voltage
Intermittent


00955 - Key 1
static



09 Central Electrics
System description: ILM Fahrer H15
Software number: 4F0910279D
Software version: 0190
Hardware number: 4F0907279

Faults:
00156 - Activation for windshield washer pump
static



61 Battery Regulation
System description: J0644 BEM H12
Software number: 4F0910181E
Software version: 0590
Hardware number: 4F0915181A
Hardware version: 000

Faults:
02272 - Static current stage 1
Intermittent


02274 - Static current stage 3
Intermittent


02277 - Static current stage 6
Intermittent


02256 - Static current
Intermittent


00532 - Supply voltage
Intermittent
53 Parking Brake
System description: EPB CA3C0040 H03
Software number: 4F0910801A
Software version: 0040
Hardware number: 4F0907801

Faults:
01487 - System function test
Intermittent


00446 - Function limitation due to insufficient voltage
Intermittent

 

My old 05 A6 had a similar issue, turned out to be the board under the buttons in the center console. Bought a used board off eBay, swapped them out, then everything came back to life.

My old board had white corrosion on some of the components (spilled liquids over the years)

 

That was actually the first thing that I had replaced, it didn't solve my problem but I don't know if I had the proper fuse in the communication slot that allows the optical wires to show the red light to the rear components. From all the videos and threads that I've read, most of them have the splash screen pop up, but I still haven't gotten to that point.

 

You mentioned you had an optical connection at all components, did you check for power at all components?

 

I know the CD Changer and Navigation Unit both have power because I can obviously remove cd's from both of them, but I don't have a single clue on how I would check power to any of the other components. I just went back into the trunk of the car, and when I "activated" the optical bus light I heard a slight popping/clicking noise which I believe is coming from the Amp. Not sure if that information will help with this case.

 

Not sure if this would work, but can you start at a component, and look for the red optical light, then look for it leaving the component. Then go to the next one, look for the light going in and out of each one?? Just a thought.

 

Well if thats the case, then all the rear components are working, but I'm unsure if that actually means everything is working.

 

Anyone know what components, fuses, or wires that would stop the initial splash screen that still pops up when the Optical Bus is open?