Fuse Check...Now MMI has stopped working :-(

[VorsprungDirk]

Hi,

I'm no stranger to the MOST loop issue having looped out a wet bluetooth module already, but everything was absolutely fine sense. I've recently replaced the Oil Level Sensor but as it never turned off the warning, I went checking fuses around the ECU and (UK)Passenger side fuse box. Needless to say, for some unspecified reason, my MMI has now decided not to work. All fuses are okay from what I've checked back and front. But now the MMI is giving the standard response where it boots, shows the boot screen, then goes dead again. I note that the cd changer lights are not lighting up suggesting no power to the cd changer. Can you help please, as this is most frustrating, and I'm out of maintenance money for the moment.

[dan2485]

you need to add the year of manufactor to be able to get help.

Is your car a 2G or a 3G MMI car?

[VorsprungDirk]

Ah...apologies :o

The car is 2005 with MMI High(color tft) 2G. Thanks for pointing that out.

[Gunnark100]

If mmi components fuses are ok like you say, no other way, run a scan and optic test with vcds...if no fixed anwser, you need to buy loop and start isolate components to see which one is problem etc...

[Bubbauk]

Check the back of the cd player, there might be another fuse there.

[Jef trayfoot]

I have a similar issue. Vcds says telephone error on optic but there is no signal going to the telephone and I don't know which module is before that one. I've done a loop break check on all 3 modules in the boot, Bluetooth under carpet and the 2 units behind the glove box plus the CD changer. Is there another module somewhere? It's a 2005 c6 mmi 2g. I get a signal to the CD changer so I know it's not a fuse.

[JulianHicks]

I have a similar issue. Vcds says telephone error on optic but there is no signal going to the telephone and I don't know which module is before that one. I've done a loop break check on all 3 modules in the boot, Bluetooth under carpet and the 2 units behind the glove box plus the CD changer. Is there another module somewhere? It's a 2005 c6 mmi 2g. I get a signal to the CD changer so I know it's not a fuse.

If you've done a VCDS optical loop test that will tell you all the optical modules in the car!

Typically the loop comes from the Control head, down to the phone, then to the back of the car, then back to the CD, returns to the Gateway and then completes the loop back to the control head.

Bear in mind, two bad devices can't be checked with one bypass loop!

Julian

[Gunnark100]

So if you isolate, cd or bt or radio or amp and restart a car, system will not wake up? Before bt should be cd and radio is after if my memory correct:)

[Jef trayfoot]

Ok. So if I get a signal going into the CD changer and if the signal isn't reaching the bt then it could be the cable. I could remove the output from the CD and put a new one in and the other end connect to the bt input and see if that works

[JulianHicks]

Ok. So if I get a signal going into the CD changer and if the signal isn't reaching the bt then it could be the cable. I could remove the output from the CD and put a new one in and the other end connect to the bt input and see if that works

Sorry, but you need to be clearer and describe what you mean by 'signal', 'reaching' and 'output'. Arte you saying that you're disconnecting the optical connection and looking at the connectors?

So that we could help you more easily it would be helpful to include the output from the VCDS Optical tests and more accvurately describe what you are removing and looking at ...

Julian

[Jef trayfoot]

Right. I have used a torch and shone it down the optical leads to make a map. Starting from bt it goes to amp, radio tuner, satnav, gateway control unit, silver box behind glove box and CD changer. That's where I'm lost. I think there is another unit between CD changer and Bluetooth but I can't locate any more. Any ideas?

[Gunnark100]

No, there is not, unless you have ami in glovebox, or some extra added toy:)

It is hard to believe that 2 units failed same time or optic is broken...but who knows...

[Jef trayfoot]

Is there an optic cable going to the screen? I have been trying to find an optic wiring diagram but cannot find one anywhere.

[Gunnark100]

Is there an optic cable going to the screen? I have been trying to find an optic wiring diagram but cannot find one anywhere.

No, all modules in optic ring you see on the table if performing optic test... mainunit, cd, telef, radio, voice,amp,tv,gate,nav,ami...all depends from options you have.

[Jef trayfoot]

Where is the voice located?

[Gunnark100]

Inside radio

[JulianHicks]

Inside radio

More accurately, the Speech unit is a seperate unit that plugs into the Radio.

It doesn't have any optical connections ...

Julian

[Jef trayfoot]

I've solved it. It was an optic cable coming from the CD changer going to the Bluetooth device. I spend last night in the dark shining a torch down each cable. I found 2 cables that didn't seem to go anywhere but that was the broken one so I took apart one of my loop breaks and used that cable to plug into the input of the bt and output of the CD changer and it all came back to life. I've ordered a length of optic cable and now just have to wait to put it all back together again. I spent £400 with the Audi dealer and had nothing to show for it. It was the knowledge of people on here that really helped. Thanks guys

[Gunnark100]

Glad mystery solved:arms:, so what is-was the location where optic is broken, just maybe this location will become common in future?

[Jef trayfoot]

Glad mystery solved:arms:, so what is-was the location where optic is broken, just maybe this location will become common in future?

It was the optic connector on the back of the CD player in the glove box. There are arrows on the cone tor to say in and out. The out goes to the Bluetooth module which is under the passenger carpet and has another optic connector with the same arrows and this was the 'in' arrow. I just took the connectors apart and put my own fibre optic wire (bought from ebay). Taking the connectors apart is easy and there are lots of YouTube videos to show how.

[Gunnark100]

It was the optic connector on the back of the CD player in the glove box. There are arrows on the cone tor to say in and out. The out goes to the Bluetooth module which is under the passenger carpet and has another optic connector with the same arrows and this was the 'in' arrow. I just took the connectors apart and put my own fibre optic wire (bought from ebay). Taking the connectors apart is easy and there are lots of YouTube videos to show how.

Im familiar with how-to etc...question was, where was optic wire broken, not how you swapped wire!:). But i guess from your reply, wire was broken behind cd box in connector(out one)!