S320 CDi key Remote opening at a distance

[MercMad1]

New member here. I have an S320 CDi 2005. The key fob will not work when a distance from the car. Only works when next to drivers door sensor. Have changed fob batteries but no effect.

 

[boxbrownie]

Hmm, I occasionally get the same issue with my 2010 ML, it cannot be the batteries as after I open the doors from very close range the car/lock/key works perfectly from a long distance....very odd indeed.

Just a thought, I assume there are replacable batteries in the fob and not accumulator type charged when the keys in the ign socket?

 

[Diesel Benz]

New member here. I have an S320 CDi 2005. The key fob will not work when a distance from the car. Only works when next to drivers door sensor. Have changed fob batteries but no effect.

Is that a W221 or a W220? Sounds like the antenna amplifier for remote control (at the rear window). The key works via infrared from short distance.

 

[MercMad1]

Thanks for the reply. Sorry for the lateness of my thanks. Christmas and the New Year got in the way. The car is a W220. The antenna amplifier for the RF signal. Is it picked up by wiring in the rear window ?

Regards

mark

 

[Diesel Benz]

Thanks for the reply. Sorry for the lateness of my thanks. Christmas and the New Year got in the way. The car is a W220. The antenna amplifier for the RF signal. Is it picked up by wiring in the rear window ?

Regards

mark

Yes, one of the FM antenna wires are used for this.

 

[MercMad1]

It looks like the culprit could be the RF antenna amplifier. Does anyone know where it is located and how to test it ? I see replacements are available on ebay.