S211 E320 CDI Aerial and Remote Locking

Hi Guys,
I have been experiencing problems unlocking my 55 plate E320 using the fob. I fitted new batteries to both keys but had to place the fobs right up to the tiny window on the drivers door handle, and even then it was very fussy about recognising the code etc. I also noticed that the Radio signal strength was reduced too with noticeable fading and interference audible. The fobs themselves have always worked fine in the ignition. I had used the key sometimes to unlock the door [and the alarm then sounds until the fob is in the ignition]. This seemed to be a fairly solid fault until the recent warm weather when everything suddenly went back to normal and the fobs would work from 50 metres away ! I am left with an intermittent problem it seems but also noted the radio was fine too when the fob "works". I have checked all of the many fuses spread around the car - I guess there is an Aerial Amplifier module somewhere ? and is the Remote locking part of its' function too ?
Any advice appreciated.

 

By no mean am I an expert, but I suggest to check both batteries in the car (rear and front). The fact that it happened more in the cold weather suggests that you have a bad battery which doesn't power up the electrics properly. Once the weather is warmer the battery gets into a better state and all might work more frequently, but still worth to try out the batteries to take this out of the equation.

 

Or could be a poor connection that makes better when warmed ?

 

Thanks Chee,
I do have a slight worry about the main battery; the Aux battery was replaced a while back and I will progress further and report back.

 

aerial amps are usually in the rear pillar (O/S IIRC) and are known to give issues. it could be, however, an issue with the wiring to/from the amp also, as the amp would affect the key range and the radio reception

 

Going close to the drivers door handle does not make any difference for the central locking,that little window is for infrared for the total closure,if you point the fob at that window and keep it pressed for a few seconds, all your window shoud open/close.

 

So when the radio locking fails (with only the IR locking still working) the radio is also poor - yes this says a problem with the antenna amp/s or antenna amp/aerial connections.

I will look some up for you - estate or saloon?

The IR function is often very poor anyway, as you will read here.

 

Hi Guys,
It is the Estate car that I have - sounds like the amplifier is tucked away quite well ?

 

i seem to think that in an estate, the amp is located in the rear side panel (rear quarter panel, remove the trims etc) as opposed to the 'C' pillar

 

There is an amp right by the aerial in the tailgate on the estates. The uppermost trim inside the tailgate needs to be removed to look see.
Worth checking all connections and earths etc.

 

Hi again,
I have put a brand new battery in the boot and it made no difference. I have also removed the tailgate trim and had a look around inside. There are two tiny wires attached to the rear windscreen [apart from the two larger HRW connectors] These tiny wires connect to the Rear Door ECU Module [A 035 545 54 32] Are these the Aerial wires ? or are the Aerial in the rear quarter glass ?
Am about to dig further in the boot.....

 

Hi,
Messed up again and created a new thread ! Duh !
Hi again,
I have put a brand new battery in the boot and it made no difference. I have also removed the tailgate trim and had a look around inside. There are two tiny wires attached to the rear windscreen [apart from the two larger HRW connectors] These tiny wires connect to the Rear Door ECU Module [A 035 545 54 32] Are these the Aerial wires ? or are the Aerial in the rear quarter glass ?
Am about to dig further in the boot.....

 

I have finally located the LH Aerial Amplifier - all looks OK with connections etc Part Number on the unit is A211 820 29 89 so I will need to scout around for another one I guess...

 

Hi there, did you ever sought this out? I have the same problem and any help would be much appreciated.

Thanks

Franz

 

Hi Franz,
Basically, I have made virtually no progress with this issue. I tried to obtain a second hand aerial amplifier but was supplied with a totally wrong part from a UK seller. In the end I got one from the USA, fitted it, and hey Presto ! - no difference at all !! Mercedes workshops don't want to help anyone and rely totally on what the Laptop tells them to do... That may well correct the problem - going through it and resetting any error codes etc. The only improvement is that the fault is solid now. The key is very erratic using the IR link [to the drivers door handle] some days it doesn't want to work at all, then on other days it will operate on most button presses. I feel sure there is a receiver of sorts behind the instrument cluster but information is very hard to come by. I have found another MB Specialist in the area and might ask them...

 

My car (same model) had a broken wire in the loom going up to the aerial amp there was a bundle of perhaps 40 wires at the lowest part of the loom behind rear wheel
Check the 3 wires at the amp for continuity at the fuse box end
Ian

 

Thanks for replies.

The IR link is a right pain. Like you it's erratic so I just need to get it fixed.

I had fault code read and deleted it without making note, duh! Gonna get it read again after work on monday.

To date I have been playing around with earths and wigglying wires at rear sam with no joy. I was gonna take out the rear aerial amp (I have no mw, sw and lw reception) but don't really want to strip everything unless I have a replacement ready to swap over.

I rang Merc main dealer and they said there are two amps at the back but problem could also be rear sam! Amps are £166, £99 and sam £450.

Hopefully fault is a wire break or one of the amps. Will keep you posted.

Regards

Franz

 

There is an antenna test that can be done with STAR, that should show how the amps are working.

 

Update, I had the fault code read.

9077 - communication with component radio signal reception of central locking is interrupted.

Is this a broken wire or amp problem?

Where exactly is the amp located? Is the amp situated on the nsr d post where the rear upper mount rear facing seats belts are located?

Thanks

Franz

 

Its closer to the tailgate hinge than the seat belts
so left hand side when standing at the tailgate remove the panel between window and headlining its directly above the side window where the wires are in the glass