Thread: Help with antenna leads w245

I need help. I have a 2008 B200/W245 with basic audio 20 and single CD. This unit has twin Fakra type antenna connections (black and mustard).

Can someone tell me what these are? I have a short roof mount antenna (OEM). Is one AM and the other FM, or are the used for something else? I'm trying to replace this head unit with an aftermarket unit with bluetooth. Everything works great except the antenna connection on the aftermarket unit is a standard motorola (din) connection. I've seen a simple Fakra to din adapters, also twin fakra to din adapters with attached amp and seperate power lead.

I'm sooooo confused can anyone shed some light on this subject? Any help would be greatly appreciated.

Thanks

Black and mustard are both radio signals. You have that correctly worked out.

It is not obvious if the power is passing back to the amplifier for the radio. The new equipment you purchased needs to send power back to the radio amp.

Apart from the conversion to DIN connections which is simple enough. You need to make sure you connect the amp power to the correct pin in the 40+4 connector which was previously in use before the change.

If im not mistaken, this car was built in 2007. The later series in 2008 have a double white fakra.

Thanks for the quick reply. The head unit that I've removed from my 2008 B200/W245 is model No. MF2751 2008.AP.January if that helps. This unit does not use a seperate amp. Would connecting an antenna adapter (fakra to standard din) to the black fakra antenna lead on my antenna work?

Thanks again

The FM/AM antennas are in the rear window. On pre Model Year 2009 cars they are powered from the head unit by one of the standard ISO wiring pins on the 4+40 multiway connector.
On MY2009 onward they are phantom fed over the coax. Cars with phantom feed have double white fakra connector, so yours is powered by a seperate feed from the head unit.

The BLACK fakra is the one that behaves like a normal FM/AM antenna, so convert that one for your new unit. But don't forget the new unit needs to supply power to the 'antenna power' feed or signal will be rubbish.

Richard

Thanks Richard. I connected the black fakra adapter and now need help with power from new unit to "antenna power lead". Any suggestions/ help on how I do this would be greatly appreciated. You were absolutely correct when you said that just connecting the black fakra would result in "rubbish reception". I get the stronger signals but that's about 6 stations in total.

In the large 40+4 there are two sockets with 12 pins (removable). In the new series, these power the armrest comfort phone and also the AUX audio.

What you are supposed to do is move (or cut) one of the wires from the "ISO" connector (the one with power wires) to the 12 pin removable connector and move all the AUX audio pins out of the way.

This minor re-arrangement offers power to the radio amp and correct AUX audio input. You may need to buy either the white or black keyed connector shell or the plastic insert which holds the pins.

Thanks again, for the information. If I understand, now that I have the black fakra (RF signal) connected to my new unit I now have to provide 12 V power to the antenna amp. using the 40+4 connector.

I have a single wire coming from the back of of my new HU that is tagged antenna +. If I understand everyone correctly I need to connect this (12v source) to a specific pin on my ISO to 40 + 4 adapter. From everything I've read (on the internet) my old Audio 20 with single CD uses pin 13 for antenna power. So somehow I now have to insert the antenna power wire coming from my new HU into the back of pin 13 on the 40 + 4 connector. How do I do that? (sorry I'm such a dummy).

Yet again any help (and patience) would be greatly appreciated.

Confused but still trying.

The new NTG 2.5 does not give power on that pin. You have to use the pin designated for "comfort phone power".

Dont confuse the old radio with the new.

What gives power to radio amplifier on the old radio no longer applies to the new one. You can also use cigarette lighter.

Thanks again all:

Still a bit confused (sorry). Got a reply from Command Online which told me from my ViN number that I have an Audio 20 NTG2.0 and that the Black Fakra is FM and the Mustard Is AM. So I'm guessing that now I need an antenna adapter that converts both the antenna leads (black and mustard) to a single din. Any idea where one might find such an adapter?

Secondly, regarding antenna amp power. My new head unit(which works great,with bluetooth, nav.system,6 virtual CD, regular CD, backup camera, ipod input, usb port.) has an isolated antenna + wire seperate from the 40+4 adapter cable supplied with unit. If the original loom in my car is expecting power on pin 13, shoudn't I try to connect the 12V power comming from my new head unit to this pin? I suspect my new unit isn't sending any power to this pin through the quad lock adapter supplied.

Have I got this all screwed up or am I on the right track. If I'm correct how do I connect to this pin can I simply tap into the wire coming out of the back of the factory loom at the pin 13 position and attach my 12v antenna lead coming directy from my new head unit?

Thanks again

In this type of car you may apply the double fakra adapter.

It converts the two fakra connectors into one double white fakra. This can be sourced from COMAND ONLINE but note that it is also the same cable used in AUDI and VW conversions. This type of conversion cable is not just for Mercedes. Maybe this helps to find it.

Secondly, the ampflier wire on the main harness wants power either from the "comfort phone power" on the new COMAND or it wants power from the cigarette lighter / 12V AUX power source.

So long as the power is switch it does not matter. It must not be a permanent power but switched on with ignition on. The two locations I have specified are the one most commmonly used.

To modify the old NTG 2.0 wiring harness you must relocate one pin from the ISO A into one pin location on the 12 pin accessory location of the 40+4 connector. The new comand only supplies power on the accessory location of the 40+4 connector. You must refer to a wiring diagram or retrofit document if you choose to make this alteration.

The microphone cable associated with NTG2.5 COMAND upgrades plugs into the additional 12 pin accessory slot on the 40+4 cable.