2006 R320CDI - no remote unlock, no FM reception

[_Lummox_]

Hello all, just bought this car at the weekend and realised on the drive home that whilst the stereo works, the radio doesn't. I already knew the remote unlocking didn't work on the car, and was hoping that would just be the battery in the key fob that needed changing, or something else straightforward...

However, I've subsequently noticed that the remote unlock function on the key does in fact work when the key is pointed directly at the IR receive on the driver's door handle. I've read on some other forums for other models that the radio antenna was used to receive the signal for the remote unlocking from the key, so I suspect that a short circuit (best guess: alarm siren battery leaked and killed the unit) has taken out the fuse causing both of the problems.

BUT I cannot find any clear guides on replacing the alarm siren on an R-class, or to tell me which fuse I should be checking in the various fuse boxes scattered around the car...

Anyone have any experience of this issue?

 

[Wighty]

Hello all, just bought this car at the weekend and realised on the drive home that whilst the stereo works, the radio doesn't. I already knew the remote unlocking didn't work on the car, and was hoping that would just be the battery in the key fob that needed changing, or something else straightforward...

However, I've subsequently noticed that the remote unlock function on the key does in fact work when the key is pointed directly at the IR receive on the driver's door handle. I've read on some other forums for other models that the radio antenna was used to receive the signal for the remote unlocking from the key, so I suspect that a short circuit (best guess: alarm siren battery leaked and killed the unit) has taken out the fuse causing both of the problems.

BUT I cannot find any clear guides on replacing the alarm siren on an R-class, or to tell me which fuse I should be checking in the various fuse boxes scattered around the car...

Anyone have any experience of this issue?

I would have a word with the seller first , they are in the hook for faults whether private or dealer sale .

 

[V6Matty]

@LostKiwi may be able to help with its location

 

[_Lummox_]

I would have a word with the seller first , they are in the hook for faults whether private or dealer sale .

Not expecting the dealer to do anything, it was a part ex trade sale and was very cheap, but the seller was clear about no warranty, no returns, sold as seen etc. I fully expected to need to change some bits and pieces under the circumstances. Just trying to figure out how best to approach it.

The car itself has a stamped FSH and lots of invoices etc, and was part ex'd for something similar but virtually new. The dealer just wanted rid as it was not in keeping with their other Bentleys, McClarens, Porsches etc they had on the lot...

 

[LostKiwi]

@LostKiwi may be able to help with its location

Yep had exactly the same on mine when we bought it.

The antenna amplifier has failed. It sits under the rear left window.
You need to remove (or partially remove) the interior left boot trim on the left side to get to it.

 

[_Lummox_]

Yep had exactly the same on mine when we bought it.

The antenna amplifier has failed. It sits under the rear left window.
You need to remove (or partially remove) the interior left boot trim on the left side to get to it.

Thanks. Don't suppose you know the part number or can describe what it looks like? I can see a couple of completely different options from breakers on eBay that claim to be the antenna amplier from a 2007 W251 car...

2007 MERCEDES-BENZ R320 W251 AERIAL ANTENNA AMPLIFIER CONTROL MODULE A1648201689 | eBay

AND IS AWARE OF OUR POLICIES. ALL OUR PARTS REMOVED FROM RHD VEHICLES (UNLESS STATED OTHERWISE). Year of Manufacture: 2007. WE AIM IS TO MAKE SURE YOU ARE ALWAYS 100% HAPPY! Part was removed from.

www.ebay.co.uk

2007 Mercedes R Class W251 Roof Aerial Antenna Amplifier A2518202275 | eBay

<p>2007 Mercedes R Class W251 Roof Aerial Antenna Amplifier A2518202275</p><p><br></p><p>MAKE: MERCEDES BENZ </p><p><br></p><p>MODEL: W251 R320 </p><p><br></p><p>YEAR: 2007</p><p><br></p><p>MILEAGE: 130451</p><p><br></p><p>FUEL: PETROL</p><p><br></p><p>BODY STYLE: 5 DOOR...

www.ebay.co.uk

I'm guessing it's the top one out of those two?

 

[LostKiwi]

Before you change anything have read the codes? It can also be the FM filter (in fact now I think back that's what mine was, not the amplifier). I changed the roof mounted amplifier but it didn't fix it.
Diags will call out the filter if it's bad. My symptoms were slightly different as my radio worked but remote locking didn't.

I can't find the part numbers I used sorry.
Mine may also be different as it's a facelift 2011 model.

 

[_Lummox_]

I don't have an MB-specific fault code reader, only a generic one (which cheerfully enough has already highlighted potential problems with the MAF and glow plug module) but don't recall seeing anything relating to the filter / amplifier. I'll have to have another look when I'm back home.

Annoyingly I have an iCarsoft scanner but it's not the MB one. Should really get one of those as my wife's car is an E-class so it would work for both.

 

[_Lummox_]

Incidentally are the modules coded to specific vehicles or if mine is duff, can I just unplug the one that's in there and plug in a replacement from a breaker?

 

[LostKiwi]

They're not coded. Simple plug and play.
And you will need a proper MB capable reader not a generic one.

 

[LostKiwi]

Some part numbers etc here but locations weren't the same on my facelift car.
Part I replaced was item 90 I think shown near A pillar. Mine was below rear left window.

Mercedes-Benz Teilekatalog (Ersatzteile online)

mb-teilekatalog.info

 

[_Lummox_]

They're not coded. Simple plug and play.
And you will need a proper MB capable reader not a generic one.

That's good to know, thanks.
Is the icarsoft one for MB up to the job or do I really need to take it an indy with a STAR setup to diagnose? There's one in my town (Welwyn Merx) but I've not used them previously.
As it currently stands I have zero fault codes now, because I spotted that the sensor beneath the left hand MAF plug was not attached using its earthing bolt (the bolt was missing). Put a bolt in there, cleared the codes, nothing came back. But the radio is still buggered and the remote unlocking still doesn't work.

 

[LostKiwi]

ICarsoft should find it. My old MB-II did.

 

[V6Matty]

The Indy you have near you is very well respected by other members on here so if you really get stuck you will be able to take it to them

 

[_Lummox_]

Got myself a Launch X431 Mercedes-specific scanner and these are the persistent codes that won't clear. Guess glow plugs and module are a good place to start?

Also the alarm siren has probably leaked and killed itself, could this communication problem with the rear SAM also interrupt the remote unlocking and radio reception?

 

[LostKiwi]

No the rear SAM code won't impact the remote locking.
It will almost certainly be the amplifier.

 

[_Lummox_]

No the rear SAM code won't impact the remote locking.
It will almost certainly be the amplifier.

Shouldn't the scan have detected a problem with the amplifier though, if the amp was at fault?

It looks like the alarm siren is duff anyway (no shock on an 18 year old car) so probably worth changing in any event.

 

[_Lummox_]

So the garage replaced the antenna amplifier today and checked for any wiring faults going to it. Didn't make any difference, still no radio reception or remote unlocking. Anyone have any other ideas?

 

[_Lummox_]

Before I dropped the car at the garage I scanned it again and got the following codes relating to the rear SAM - could the suppression one be the problem?

 

[LostKiwi]

Before I dropped the car at the garage I scanned it again and got the following codes relating to the rear SAM - could the suppression one be the problem?

Yes that's exactly what failed in mine. In mine radio still worked but c/l didn't. There's a thread somewhere.

Part number A1648205489.
Around £54.