[Admir Huric]

I just got a 2002 w211 e270 as a part of some debts owed to me. One thing that is strange is it has two antennas, one on the roof, and one on the rear window. One on the roof does not have any plastic around it and seems to be cut off. A couple of problems with these antennas:

- FM Radio is not working most of the time, only time when it catches a couple of stations is when I am in the city center
- I can't unlock/lock/open trunk from any distance, instead I have to put my key directly on to the lock, and then press unlock/lock button, and then somehow it works
- The GPS is not working (it came with GPS cd inside the car)


So, if anyone can explain to me what these 2 antennas are for, do I need both of them, and how to fix these issues, I would be more than grateful.

Thank you. (Images attached)

 

[Skylaw]

Somebody has tampered with your antennas; for what purpose I do not know.

First, there should not be that connector protruding through the sheet metal on the roof. It is no part of any original Mercedes installation. I have no idea what it was for.

Second, your "shark fin"antenna looks as if it has been taken off and re-glued. That antenna contains your GPS antenna and one of two cell phone antennas (the second cell phone antenna, at least in North American cars, is in the rear bumper).

Your AM and FM radio antennas, as well as the antenna for the door locks are in the glass of your rear window. They connect to several low-powered linear amplifiers located between the sheet metal of the roof and the headliner, just in front of the rear window frame. Loss of AM and FM radio is likely the result of failure of these amplifiers.

If your rear window has metallic tint applied over the glass, this will also cut down reception. Only ceramic-based tint should be used.

Your smart key operates on both radio frequency (with the signal being received at the rear window) and Infrared (with the signal being received at the black square lens in the door handle). Apparently the key is functioning with infrared, so its batteries are likely good. However, the potential sources of problems are a bad circuit in the key, and a bad linear amplifier (next to the radio amplifiers; all go on the same mounting bar).

Although your car is quite different from the later model W220s, the general operating principles of the antenna system are the same; specifics may differ. See http://www.benzworld.org/forums/w220-s-class/1834026-w220-antenna-system-key-fob.html

Also, for the key, see http://www.benzworld.org/forums/w220-s-class/1646105-battery-died-now-key-wont-unlock.html - and especially, try the steps at post 24.

 

[Admir Huric]

@Skylaw
Thanks for a quick and resourceful response. I will be sure to check the links out. I really want to take this thing to a certified electrician, and see what he has to say about.
Most logical thing I concluded is that this particular mercedes was a taxi car for some time. That would explain the added antenna that goes through the roof, obviously added as an aftermarket part, if no vehicles were produced like this. I also saw a couple of W211's in the city that had their antenna on the roof, instead of rear window, so that left me guessing.

 

[Skylaw]

The W211s I am familiar with ordinarily have their antennas placed as in the photo below.

More on the key and locks: It would probably not hurt to replace the battery (or batteries) in the key. Ordinarily the IR can be used up to 3 feet from the sensor in the door handle, except in strong sunlight (sunlight on the sensor seems to interfere). That you must place it directly on the door handle may indicate a weak battery.

Once you know the batteries are good you can check whether the linear amp mentioned before is the problem; place the key directly on the wires in the rear glass and see if the locks will work. If so, the linear amp has likely failed. You may have to experiment to see just which set of wires are for the door locks.