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Discussion Starter · #1 · (Edited)
Had a little bit of an issue with the S5 a few days ago, the MMI stopped working.

Have done a bunch of searches but can't figure out what I need to do etc.

I've run a scan with VAGCOM and it couldn't communicate with the MMI stuff, so did the MOST diagnostics which come back with

Control Module Part Number: 8T0 907 468 K
Component and/or Version: GW-BEM 4CAN-M H09 0092

Optical Bus Diagnostic : Standard

Controller Electrical Optical
19-CAN Gateway OK OK
07-Control Head(High/D3) OK OK
0E-Media Player 1 OK OK
1E-Media Player 2 OK ERROR
77-Telephone OK ERROR
47-Sound System OK OK
56-Radio OK OK
37-Navigation OK OK

And also did a gateway search which come back with
Gateway Installation List: 8T0 907 468 K

01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: Malfunction 0010
06-Seat Mem. Pass -- Status: OK 0000
07-Control Head -- Status: Cannot be reached 1100
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: OK 0000
0E-Media Player 1 -- Status: Cannot be reached 1100
10-Park/Steer Assist -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: Malfunction 0010
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
1E-Media Player 2 -- Status: Cannot be reached 1100
36-Seat Mem. Drvr -- Status: OK 0000
37-Navigation -- Status: Cannot be reached 1100
42-Door Elect, Driver -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: Cannot be reached 1100
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
55-Xenon Range -- Status: OK 0000
56-Radio -- Status: Cannot be reached 1100
77-Telephone -- Status: Cannot be reached 1100

The malfunctions are irrelevant, I know what they are (actuator stuck on HVAC, wiper intermittent switch had a glitch but works fine now, key battery low).


Am I right in thinking the issue with the MMI is the optical MOST bus is broken between Media Player 2 and Telephone? So it's either one of these modules failed or the optical connection has come apart?

I have it booked in at the main dealer however there's a 3 week wait, if it's a simple fix I'll probably try it myself in the mean time but, no idea where or even how to get to the media player 2 and telephone modules.

Any help, guidance etc. would be most appreciated.


Edit: The CAN Gateway malfunction shows this
3 Faults Found
03041 - Energy Management Active
000 - - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 7
Fault Frequency: 5
Reset counter: 59
Mileage: 128058 km
Time Indication: 0
Date: 2017.10.17
Time: 16:49:00

00384 - Optical Databus
011 - Open Circuit
Freeze Frame:
Fault Status: 01101011
Fault Priority: 5
Fault Frequency: 1
Reset counter: 17
Mileage: 128078 km
Time Indication: 0
Date: 2017.10.19
Time: 16:59:53

02256 - Quiescent Current
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 7
Fault Frequency: 1
Reset counter: 60
Mileage: 128086 km
Time Indication: 0
Date: 2017.10.19
Time: 21:23:00
 

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Energy management active points to a low battery. This will switch off power consumers.

What's the state of charge of your battery ?
 

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Discussion Starter · #3 ·
Thanks.

Checked the battery voltage (via Torque) tonight. 11.7v standing and 14.4v while driving. I know the MMI used to tell me it was about "half full" for a while and 11.7v I believe is about 1/3 charged so could be that I guess. Not sure if it's ever been changed (certainly not in the 4 years I've had it) - I only just learned where it actually is in the car.

Hopefully that's what the issue is, however shouldn't it all come back to life if there's a consistent 14.2-14.4v while driving? Or is it more advanced and high tech than that?
 

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While driving is the voltage from your alternator though which I'd expect to be in the 14.4v range.

The battery itself is needed for starting and and retaining settings for modules etc. I'd suggest charging it using an intelligent charger. 11.7 volts is too low, which is why the energy management has kicked in.
 

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I'm not sure exactly when Audi introduced it, but some have energy recuperation. When you brake (and maybe other times), the alternator is switched into high energy mode, raising its voltage slightly (and using a bit more engine power) and putting a bit more charge into the battery. This can explain why you see a fluctuation during driving. But I'm doubting this tech was on a 2008 car.

Agreed on the 11.7V - that's far too low. Supposedly batteries should last around 5 years but I have never been so lucky. If its at least 4 years old and that 11.7V is correct then I advise you to replace it before it lets you down. There's no point in trying to diagnose any other faults if the energy management system is possibly turning components off to conserve power.
 

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Discussion Starter · #6 ·
Thanks, I'll give changing the battery a go before it goes in.

Is there a specific battery/part number etc. for the S5 battery? Have searched around but only see that it needs to be coded to the vehicle once changed (which I can do as i have VCDS) but no mention of if it has to be a specific battery or has to be an audi genuine part etc.
 

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There will be a part number on your battery under the boot floor
 

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Discussion Starter · #8 · (Edited)
Thanks so much!

Replaced the battery tonight (was a varta 8ko 915 105 f changed for Bosch equivalent ( Bosch S5 S5 Battery 020 - Part no. 444779008 - £279.99 from Euro Car Parts, less £112 voucher code so £167.99) since it's a rebadged Varta). Instantly fixed the issue without the need to re-code the car.

Just spent about 30 minutes re-coding the battery change and running scans etc. and all working now (with the exception of the HVAC issue which the main deal will sort)

I can't thank you guys enough, not that I'm cynical but probably saved me a few hundred quid at Audi (they wanted the car for 2 days to diagnose this - they had all info I posted here)


Address 19: CAN Gateway (8T0 907 468 K)

17:57:48 Group 019: Power Supply (Battery)
84.0 % Battery State of Charge (SOC)
80.0 % Battery State (as shown in MMI)
98.0 % Battery Aging (derived fr. Load)
95.0 % Battery Aging (derived fr. Output)

17:57:48 Group 020: Power Supply (Battery)
3.8 mOhm Internal Battery Resistance (actual)
3.4 mOhm Internal Battery Resistance (stan.)
64 Ah Battery Capacity (actual/available)
12.50 V Quiescent Voltage



Very happy man now, couldn't have done it without you. Now I also know just how much info VCDS can give too I may tackle the HVAC issue myself.
 
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