Control Unit Not Responding - Autel

[W212Chris]

Morning all,

please see the attached pic for further detail. My Command Unit is no longer working. I have checked and charged the Aux battery but to no change.

Running my Autel Diag reports an issue with the HU and MOST. Further tests using the live Wake-up line shows the Media Interface as not responding ?

Any tips on where to go from here ?

Chris

 

[alexanderfoti]

Its coded to NO so I would assume the car is not equipped with the tv tuner. In which case, its querying a module that does not exist.

I would think that you are in the Comand module to be able to run that test, so you have comms with the Comand unit itself.

What is the issue?

 

[W212Chris]

That is correct, there is no TV so I am not concerned about that. Its the Media Interface that is not reached. The Command screen is completely blank, there is no power to the keypads but I can hear the CD player whirring.

I have checked all the fuses, recharged the Aux battery but still nothing.

 

[alexanderfoti]

Does the screen light up with the MB logo then go dark, or no response at all

 

[W212Chris]

Nothing, no logo etc.

 

[alexanderfoti]

Checked the basics? Fuses, power at the comand unit plugs? I have replace a few for just going fully dead with no comms

 

[W212Chris]

That would be the logical step I suppose. All the pre unit fuses I have checked and are fine. Now need to remove the HU itself and check the back for the fuse. ?

 

[W212Chris]

Full Autel diag

HU(Head Unit Control Unit) ( 4 DTCs )DTC Description Status
D016 MOST communication has a malfunction (position of ringbreak cannot be identified). Active and stored
D017 MOST communication has a malfunction (MOST masterreporting ring break). Active and stored
C255 Communication with the central display has amalfunction.Active and stored(Eventcodes)
D185 Communication with the control panel 'Head unit' has amalfunction.Active and stored(Eventcodes)

 

[alexanderfoti]

I was going to say, I have done a few screens as well, can you communicate with the central display as a seperate item?

 

[W212Chris]

Ok so took the unit out and checked the fuse. Nothing wrong with it. Checked the condition of the cabling attached and its perfect. Not even sure now of where to go next so any pointers would be appreciated.

 

[Flyinspanner]

MOST ring break - that is the optical loop, any break or unit fail ie HU / amp/ cd changer/ etc will stop signal around the whole system.

You can get a loop plug and in turn ‘short’ each unit, to see if it fires up again. Check any fuses on each item ie little fuse on CD unit.

 

[W212Chris]

MOST ring break - that is the optical loop, any break or unit fail ie HU / amp/ cd changer/ etc will stop signal around the whole system.

You can get a loop plug and in turn ‘short’ each unit, to see if it fires up again. Check any fuses on each item ie little fuse on CD unit.

Checked the fuse on the CD Unit and its fine. There is power to the facia, i.e. keypad and function buttons but no Screen. I can see the SAT Nav, phone etc on the steering wheel cluster but no other options.

Regarding the MOST - I have been searching for a diagram for my S212 but can not find anything.

 

[Flyinspanner]

When looking at the optical loop, I just bought a ‘loop’ (but for the D2B system, slightly older spec /differing plugs) and went to each unit. It turned out to be a dead amp, which I replaced from the ‘Bay.

there is a tiny fuse on Bose amps too. (It was fine, just amp had blown)

 

[W212Chris]

Just completed another Autel live test and now have the following errors with regards to the Command Screen. I have manually restarted the MOST ring but no change.

 

[alexanderfoti]

My experience with a MOST ring break is that the head unit gets stuck in a boot loop, only showing the MB logo and then powering off.

Not sure how the head unit module can report no comms with the head unit module......

I'd be thinking a faulty head unit at this point, but you could loop the most ring at the head unit and see if it boot loops.