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2005 SLK55 AMG
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Discussion Starter · #1 · (Edited by Moderator)
When I start the car or try and select any function the mercedes logo appears on the comand screen (screen working) as if its starting, then screen goes blank a few seconds later. I have done a battery dis connect for an hour but no effect. Any ideas what next ?
 

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2008 SLK350
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3,600 Posts
When I start the car or try and select any function the mercedes logo appears on the command screen (screen working) as if its starting, then screen goes blank a few seconds later. I have done a battery dis connect for an hour but no effect. Any ideas what next ?
Probably MOST optical ring interrupted.
 

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Founding Member 2006
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113,395 Posts
i have removed that 2nd 'm' from comand for you... no charge :D
 

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2008 SLK350
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All the infotainment stuff in your car is connected to each other in a ring configuration. An optical ring als known as the MOST ring. If the ring is interrupted everything on the ring fails and the symptom you describe sounds like that is the case.
Looking at your datacard you have the following devices on this ring:
  • the HU
  • telephone module (located near the rear SAM in the trunk)
  • navigation unit in the trunk
  • CDC in the glovebox
  • AGW (Audio GateWay,the device that controls the ring) in the passenger footwell.

If one of these devices (or more than 1) fails everything on the ring becomes inoperable.
Unfortunately impossible to tell which one from here. SDS has some diagnostic capabilities that might pinpoint where the problem is.
One thing you can easily do yourselves is checking the fuses of these devices.

And there is also the possibility that an optical wire is broken or an optical connector dislodged.

Afraid there is no easy fix to tell from my end,you will have to search.

Some good info you can find here https://www.billsden.org/mercedes/slk/docs/train_audio_comm.pdf .

HTH
 

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2007 SLK55 AMG
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2005 SLK55 AMG
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65 Posts
Discussion Starter · #10 ·
and... just an fyi...do you put drinks in the cupholders over the screen?

no never have
All the infotainment stuff in your car is connected to each other in a ring configuration. An optical ring als known as the MOST ring. If the ring is interrupted everything on the ring fails and the symptom you describe sounds like that is the case.
Looking at your datacard you have the following devices on this ring:
  • the HU
  • telephone module (located near the rear SAM in the trunk)
  • navigation unit in the trunk
  • CDC in the glovebox
  • AGW (Audio GateWay,the device that controls the ring) in the passenger footwell.

If one of these devices (or more than 1) fails everything on the ring becomes inoperable.
Unfortunately impossible to tell which one from here. SDS has some diagnostic capabilities that might pinpoint where the problem is.
One thing you can easily do yourselves is checking the fuses of these devices.

And there is also the possibility that an optical wire is broken or an optical connector dislodged.

Afraid there is no easy fix to tell from my end,you will have to search.

Some good info you can find here https://www.billsden.org/mercedes/slk/docs/train_audio_comm.pdf .

HTH
thank you for this info, will check the fuses and try and find all these units
All the infotainment stuff in your car is connected to each other in a ring configuration. An optical ring als known as the MOST ring. If the ring is interrupted everything on the ring fails and the symptom you describe sounds like that is the case.
Looking at your datacard you have the following devices on this ring:
  • the HU
  • telephone module (located near the rear SAM in the trunk)
  • navigation unit in the trunk
  • CDC in the glovebox
  • AGW (Audio GateWay,the device that controls the ring) in the passenger footwell.

If one of these devices (or more than 1) fails everything on the ring becomes inoperable.
Unfortunately impossible to tell which one from here. SDS has some diagnostic capabilities that might pinpoint where the problem is.
One thing you can easily do yourselves is checking the fuses of these devices.

And there is also the possibility that an optical wire is broken or an optical connector dislodged.

Afraid there is no easy fix to tell from my end,you will have to search.

Some good info you can find here https://www.billsden.org/mercedes/slk/docs/train_audio_comm.pdf .

HTH
Pete
thank you very much for this, started checking the fuses and first one checked, HU fuse 26 blown (40A), tried to replace but replacement blew straight away with ignition off, so i guess I have an open circuit? will start with the fuse assembly unless there is something more obvious?? I am mechanically good, electrical naive
 

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Discussion Starter · #11 ·
no never have


thank you for this info, will check the fuses and try and find all these units

Pete
thank you very much for this, started checking the fuses and first one checked, HU fuse 26 blown (40A), tried to replace but replacement blew straight away with ignition off, so i guess I have an open circuit? will start with the fuse assembly unless there is something more obvious?? I am mechanically good, electrical naive
Not sure what to do now, wiring to fuse unit looks o.k. ??
 

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2008 SLK350
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3,600 Posts
Not sure what to do now, wiring to fuse unit looks o.k. ??
Well,looks like you have a short somewhere.
According to the fusechart fuse 26 is for the complete radio system in pre-FL cars.
So problem can be with any of the devices mentioned.
I would disconnect them all and then connect them one by one to see which one causes the short.
 

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Discussion Starter · #13 ·
Well,looks like you have a short somewhere.
According to the fusechart fuse 26 is for the complete radio system in pre-FL cars.
So problem can be with any of the devices mentioned.
I would disconnect them all and then connect them one by one to see which one causes the short.
brilliant, disconnected HU, fuse still blew, disconnected AGW no fuse blow so I guess its the AGW, is this unit repairable or do I need to source a replacement?
 

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Founding Member 2006
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113,395 Posts
replacement cost if available

A 211 870 67 89
AMPLIFIER
AUDIO GATEWAY; AGW

Sale Price:$1,819.40

 

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2008 SLK350
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3,600 Posts
brilliant, disconnected HU, fuse still blew, disconnected AGW no fuse blow so I guess its the AGW, is this unit repairable or do I need to source a replacement?
If you do a search with 'Comand repair" you will find some UK shops that do repairs.
Should you choose to replace it make sure you buy a European and not a US unit. The AGW also houses the AM/FM tuner and there are differences regarding this between US and EU.
But once you have the unit removed I would first take a look myself. See if you can find where the short is. May ve as simple as a dodgy connector.
 

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2005 SLK55 AMG
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65 Posts
Discussion Starter · #16 ·
replacement cost if available

A 211 870 67 89
AMPLIFIER
AUDIO GATEWAY; AGW

Sale Price:$1,819.40

Geoff
its a HK 7 system so the AGW unit is A2118701489 (as on label) which was replaced by A2118704089 from the parts listing, which I guess would be more expensive, so will be looking at e bay after next weeks holiday
 

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Founding Member 2006
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Geoff
its a HK 7 system so the AGW unit is A2118701489 (as on label) which was replaced by A2118704089 from the parts listing, which I guess would be more expensive, so will be looking at e bay after next weeks holiday
nope

4089 replaced by

6789

50
A 211 870 67 89
AMPLIFIER
AUDIO GATEWAY; AGW
1
Code: (525/527)+810/810;
Replaces: A 211 870 40 89
Replaces: A 211 870 14 89
Replaces: A 211 870 17 89
Replaces: A 211 827 45 42
 

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2005 SLK55 AMG
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65 Posts
Discussion Starter · #18 ·
If you do a search with 'Comand repair" you will find some UK shops that do repairs.
Should you choose to replace it make sure you buy a European and not a US unit. The AGW also houses the AM/FM tuner and there are differences regarding this between US and EU.
But once you have the unit removed I would first take a look myself. See if you can find where the short is. May ve as simple as a dodgy connector.
thank you for all your help today, I have learn't a lot, had a quick look for repairers (struggling) and e bay (£250), and will have a look at the unit after my holiday next week
 

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Founding Member 2006
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all the above is from your vin by the way! :D your serve
 

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see my post 17 above
 
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