Central locking RF antenna issue. (I think)

[churcherj]

Hi all. Over the last few days my car has just developed an issue with the central locking. Car is a 2008 c220 cdi wagon w204.

It works up close to the drivers door (IR) but anything with range it doesn't work. My radio is fine, but after some reading I've bought a new antenna amp module and will swap it over. I've noticed on the back screen there is a yellow wire (gelb) which is connected to the antenna amp, there is also another connector on the left called schwartz, but there isn't a wire going to it. It looks like something has broken off. Can anybody shed some light as to what this is?

This is at the top left of the rear windscreen as you look at it.

I'm. Loving my merc, first one I've owned but mine seems plagued with electrical issues. Also got the glow pkug light on, replaced all of them and no error codes but I think the relay has gone also. Had a lot of random electrical issues!

Hope you guys can help and whether replacing the antenna will work. By the way done the obvious and replaced fob batteries with 3 different new packs, and spare key also does the same. My radio functions although I only use FM. Cheers

 

[toolman1954]

Hi.
Some long time ago I had a similar problem with the central locking on my old E320 cdi wagon. It is documented on here in a past post, so I will not bore you with the details. However the cause of the problem was not the aerial amp but turned out to be a broken wire between the aerial amp and the fuse box. It was not the easiest of diagnosis. Just to add though that my radio signal had almost gone.
Now with regard to your rear window, Schwarz means black, so assume you are a black wire or connection of some sort missing. I would perhaps ask on here for another 2008 cdi owner to oblige and take a pic of the same connection. Once you know what is missing, then look for a wiring diagram, and repair the wire. It might be that the connection is not easily repairable and it is easier to replace the window or the whole tailgate.
Steve.

 

[churcherj]

Hi.
Some long time ago I had a similar problem with the central locking on my old E320 cdi wagon. It is documented on here in a past post, so I will not bore you with the details. However the cause of the problem was not the aerial amp but turned out to be a broken wire between the aerial amp and the fuse box. It was not the easiest of diagnosis. Just to add though that my radio signal had almost gone.
Now with regard to your rear window, Schwarz means black, so assume you are a black wire or connection of some sort missing. I would perhaps ask on here for another 2008 cdi owner to oblige and take a pic of the same connection. Once you know what is missing, then look for a wiring diagram, and repair the wire. It might be that the connection is not easily repairable and it is easier to replace the window or the whole tailgate.
Steve.

Hu Steve thanks for the response. So I actually replaced the amp antenna module today with no luck. Still doesn't function so I think I need to check the cables as mentioned. If anyone else knows we're the black cable is missing it would be useful. I cannot see any broken wire that goes to it, or if that is the problem. What a pain. I've had so many electrical problems with this car.

 

[Nesport]

Hi all. Over the last few days my car has just developed an issue with the central locking. Car is a 2008 c220 cdi wagon w204.

It works up close to the drivers door (IR) but anything with range it doesn't work. My radio is fine, but after some reading I've bought a new antenna amp module and will swap it over. I've noticed on the back screen there is a yellow wire (gelb) which is connected to the antenna amp, there is also another connector on the left called schwartz, but there isn't a wire going to it. It looks like something has broken off. Can anybody shed some light as to what this is? View attachment 108660

This is at the top left of the rear windscreen as you look at it.

I'm. Loving my merc, first one I've owned but mine seems plagued with electrical issues. Also got the glow pkug light on, replaced all of them and no error codes but I think the relay has gone also. Had a lot of random electrical issues!

Hope you guys can help and whether replacing the antenna will work. By the way done the obvious and replaced fob batteries with 3 different new packs, and spare key also does the same. My radio functions although I only use FM. Cheers

Hi churcherj, i have a merc 220 cdi w211 year 2006 and had the same problem, i swapped out the antenna module, checked all the fuses and wires with a schematic, all was good, so i took out the (SAM) which is a fuse box that is on the left hand side of the boot behind the cover that covers everything, so you dont see wires etc... , i then saw a burnt wire that brings 12v, it even burnt the plastic on the fuse box, see in photos, i then opened it up and found it was full of moisture and white traces of oxidization, so i cleaned all the electronic components and contacts, i had to desolder the PC board to get to the other side of the components as you can see in the photos, and now all is fine.
I also repaired the IR central locking on the door and checked the key, you can find that repair if you google it.
The SAM is what contrôles all the comfort of the car including fuel gage, central locking, dashboard etc... , then there is another SAM in the front left hand side when you open the bonnet, and that one is for the motor and all the rest of the components ex : ABS, ESP etc...
Hope this helps you and others with the same problems.
Regards

 

[Petrol Pete]

Hi Church , welcome. Your phot looks like moisture has got into that area and corrodes the connection. This is the top of your windscreen and the photo is upside down , right ?

 

[churcherj]

Hi churcherj, i have a merc 220 cdi w211 year 2006 and had the same problem, i swapped out the antenna module, checked all the fuses and wires with a schematic, all was good, so i took out the (SAM) which is a fuse box that is on the left hand side of the boot behind the cover that covers everything, so you dont see wires etc... , i then saw a burnt wire that brings 12v, it even burnt the plastic on the fuse box, see in photos, i then opened it up and found it was full of moisture and white traces of oxidization, so i cleaned all the electronic components and contacts, i had to desolder the PC board to get to the other side of the components as you can see in the photos, and now all is fine.
I also repaired the IR central locking on the door and checked the key, you can find that repair if you google it.
The SAM is what contrôles all the comfort of the car including fuel gage, central locking, dashboard etc... , then there is another SAM in the front left hand side when you open the bonnet, and that one is for the motor and all the rest of the components ex : ABS, ESP etc...
Hope this helps you and others with the same problems.
Regards

Thanks for the reply! Looks like quite an involving job! It could be the culprit to my electrical issues as I seem to have quite a few. I'll look into this today!

 

[churcherj]

Hi Church , welcome. Your phot looks like moisture has got into that area and corrodes the connection. This is the top of your windscreen and the photo is upside down , right ?

Hi Pete, thankyou! Yes this is the top of the windscreen. When I took all the trim away there was some water that came out so there has definitely been moisture in there, so would potentially explain some of the electrical issues. My problem is I cannot see the black wire anywhere that supposedly goes to this connection. On my icarsoft I've got a lot of historical errors on the SAM such as windscreen breakage, tow bar connector, alarm siren Malfunction etc.

The current code Coming up is "the two way radio receiver has a malfunction". I certainly think that water could be the issue to some of these problems. Not sure how moisture has crept in.

 

[Petrol Pete]

If the windshield has been replaced and the fitter did not seal it properly this can happen. What is worse (on some models) is that hidden behind a badly fitted replacement window seal the car starts to rot away where road salt gets in and is not washed out, small bubbles might appear behind the paint that on first inspection look minor, but underneath the damage is major.

 

[toolman1954]

Hi,
As you have replaced the aerial amp best now trace the wires to the rear SAM ( fuse box )using your trusty multimeter. According to my old thread it was the red/ white wire from the amp to the fuse box that was the culprit.
Many electrical problems can be caused by water ingress or the very worst is rodents, mice, rats etc. At least with an older vehicle fuse boxes off of Ebay are often cheap.
Just to bore you here below is the last part of my thread from Dec 17...that long ago !!



......Well this whole episode has been a bit of a head scratcher.
I had tried 2 different aerial amplifiers, transmitting about 1 watt on 5Mhz to check the aerial reception and a couple of times over the last 3 weeks the Radio stations and key fob started working again and then in an instant stopped.
Sunday, now back in Northampton, I replaced the rear SAM N10/2, still no key fob / radio stations. I put the MB2 scanner on to check everything and lo and behold there was a code 9077. ( Communication with component Radio Signal reception of the Central Locking System is interrupted.)
So next I did a search on Google using this code. There was a thread on another MB site with exactly the same symptoms of my problem, and the fault was a broken red/white wire from the Aerial Amp in the roof which went to a green socket on the N10/2. Two people there had suffered the same fault.
So I pulled the plugs on the Aerial Amp and N10/2 and tested them for continuity and the buzzer on the meter was silent. I jammed a piece of wire into the two sockets and connected them back up. Radio working and key fob working .....hallelujah !!
I dare say that fitting the replacement SAM finally pulled the broken wire apart causing the fault code.
I have now just cut the red/white wire and spliced in a new section of wire.
Fitting the SAM seems to have caused another problem, that the fuel gauge is not working. I have posted another thread for some wiring help on this.
Thanks to all who came up with suggestions to help me resolve this problem...... (replaced original SAM)