eqplayer11

I looked through the forums and i could not find anyone with a similar problem as mine. the signal from my remote key to the sensors are weak. I replaced the batteries and it did not help at all. The light on my key lights up when i push. The only way i can make the remote work is if i place the key right up to the sensor on the front left door car handle. Some times it will work a foot or two away but not usually. What is really weird is if i try to open the door from the right side of the car it will work from up to 8 ft away. When i bought the car the dealer told me i just needed to replace the batteries and that didnt help 8(. Im looking for a few ways to try to diagnose this myself without having to pay alot of money to the dealership. Im wondering if its the sensor in the car door handle that is causing this? or could it be a fuse? or a loose wire in the sensor? any help would really be appreciate thank you.

eqplayer11

Also can anyone send me a fuse box/panel diagram for a 2004 Mercedes C240? my email is tylerketner@YAHOO.COM

Glyn M Ruck

This has been covered many many times. The RF side of your key is down, only IR working. The problem is usually caused by the antenna in the rear window glass not receiving correctly.

Causes.

Fitting a metallic tint to the rear window
Water from tint
Wires cut at top dead centre of the screen while fitting a tint
Sticky connector pad at TDC of the rear window has come unstuck
Antenna amplifier is blown or has a poor earth.
RF failure of key itself.

How is your radio reception? - have you had a recent tint? Answer these comments & I will guide you

Glyn M Ruck

eqplayer11

Thank you so much. the radio reception is excellent in my car. No tint at all on it either. I dont believe it is the key itself because the reception on the right door handle works from 8 foot away

eqplayer11

and also my 2004 c240 does not have a visible antenna ata all, like the one shown in that diagram

Glyn M Ruck

Here is your fuse diagram




If both FM & AM reception on your radio is good then it seems the RF system is operating properly. It uses the same long distance antenna as the key.

Do you have a spare key to try?

If not it appears that the RF side of your key has failed & you will need a new one. A bit expensive & a pain because they have to come from the Merc central security centre - ordered via a dealer who will need your VIN.

Glyn M Ruck

The RF antenna is embedded in the glass with the heating/demisting element

Glyn M Ruck

If you point the key at the door handle from about max 10 feet away the key is operating by infra red not RF. At greater distance it operates by radio frequency.

The batteries in the key energise both the RF side of the key & the IR side of the key. That little red widow in the end of the key & on the door handle are the IR sender & receiver.

To complicate issues - when you put your key in the ignition then the EIS (electronic ignition switch) energises the key inductively like your electric toothbrush charger. Once you have the key in the ignition the batteries do nothing.

matamorfosis

I have the same exact issue, 2001 C240 and my radio reception is not very good. Please help!
Regards

matamorfosis

Where is the reference for the above diagram? Antenna Install Pillar Roof .jpg

Frankcar

Hello
C180 W203 2005 not working remote with frequency , CAR Start , central locking and IR remote work good , not have DTC with scanner device
EIS 2095451908
F8 Fuse of rear sam good and have power 12v
i make two key 315MHz and 433Mhz for this EIS but not working remotes , Only lock and unlock of IR remote near driver door
Which computer have DTC if antenna crashed ?
how i can test antenna and receiver ? not have spare part for replace test
for removing antenna i need to opening roof cover ?
someone can help me what is the problem ?
Thanks - best regards

Ahmer

having the same problem. Do I replace the amplifier and the antenna together? or is it 1 part? I have a w203 2001 sedan.

jvel3857

[QUOTE=Glyn M Ruck;4347638]This has been covered many many times. The RF side of your key is down, only IR working. The problem is usually caused by the antenna in the rear window glass not receiving correctly.

Causes.

Fitting a metallic tint to the rear window
Water from tint
Wires cut at top dead centre of the screen while fitting a tint
Sticky connector pad at TDC of the rear window has come unstuck
Antenna amplifier is blown or has a poor earth.
RF failure of key itself.

How is your radio reception? - have you had a recent tint? Answer these comments & I will guide you[/QUOTE

jvel3857

I just had old tinting which was bubbled removed processed used by tinting company was steam, they then replaced the new tinting afterwards. The day I picked up the vehicle I noted my key fob was no longer working.
I've looked at fuses and replaced the rear trunk sams as well, it still no longer works. I'm wondering now if it may be as a result of having the windows tinted recently.

S70Houston

I had exactly the same symptoms, I needed to change the antenna amplifier and all is good since, with tint as well.