Mercedes-Benz Forum banner
1 - 14 of 14 Posts

·
Registered
2004 CLK 500
Joined
·
94 Posts
Discussion Starter · #1 ·
Where are the sensor(s) for the smart key? I just got my car back from being serviced and the smart key will hardly work at all. It has always worked from tremendous distances and at virtually any angle. Now, I have to be standing next to the driver's side of the car, and even then it will only work sometimes. I have no idea what the service folks could have done (normal B sevice and playing with a right headlight problem), but I figure its got to be simple, like the sensor in the car is covered. The batteries are fine. Any thoughts??
 

·
W210 Moderator
99 E320
Joined
·
5,365 Posts
if your setup is similar to W210, the IR works on windows/roof, but the RF is for door
un/lock. as a stop gap fix, you can try the 'chin' method and touch the IR on the
smartkey to your jaw bone and it should radiate and buy you a little more range.
I've determined that the antenna is up near the inside rear view mirror and have
been trying to figure out if the antenna can be improved. no luck yet.
 

·
Registered
Joined
·
144 Posts
Just some useful info for everyone who has key problems. MB keys work in 2 ways. Radio Frequency and Infrared. Infrared will only work within I beleive like a 4 foot range. After that its information is comunicated thru RF. If you want to determine if your key is faulty or if its a problem with the car, there are a few things to try. One, the red light on the remote should light up everytime you hit a button. If it doesn't... you have a key problem. Two, the convenience opening/ closing of the windows, sunroof or top are all done thru the IR signal transmitted to the sensors in the door handle (the little square lense there). If this feature works, then the IR function of the remote is okay. Third, you can determine iof you have a RF problem by placing the key in your pocket (if the lights light up all the time!) and pressing the butons should unlock, lock, etc. Fourth, if say your remote lights up, and nothing works, take your key and point it into a camera lense. Look at the camera lense while pressing the buttons, if your IR transmitter in the key IS working, you will see flashes of white light in the camera lense. Thats all the general key tests I know of. But you all should try the Fourth cause its cool.
 

·
Registered
2004 CLK 500
Joined
·
94 Posts
Discussion Starter · #5 ·
I'm not sure how mine got fixed, but here's what happened. The dealer determined that the com bar was faulty and replaced it. This fixed my problem some, but not much. The smart key worked better, but still not nearly at the far distances that it had always worked.

I then had to take the car in to have the headlamp control units replaced because the xenons were occilating up and down as I was driving. When I got the car back this time, I had almost no radio reception - I have no idea what the mechanic did with the headlights that made the radio reception go south.

I then took it back to have the radio reception fixed. They found no codes and doule-checked that the com bar that they had replaced before was the correct part number - it was. So, what they did was update the software.

Instantly, everything worked - the radio reception is now stronger than when the car was new, and the smart key will again work from very long distances.

I'm not sure what software was updated, but it obviously had to do with the com bar. The com bar is in the rear of the roof and is part of the antenna system (I think). It is also what picks up the radio signal from the smart key and transmits the signal to the locks. Since 2 of my problems (smart key and radio reception) had to do with radio reception, I guess the software upgrade to the com bar is what fixed them both (although the service manager is bewildered and has no idea how he did such a great job).

Hope this helps.
 

·
W203, W210 Moderator
E55 ///AMG
Joined
·
6,911 Posts
just a little article about Smart Key.

The key fob utilizes a radio-frequency transponder to communicate with the door locks, but it uses infrared to communicate with the engine immobilizer system. Original SmartKeys had a limited frequency and could have only been used in line-of-sight for safety purposes. In addition to the SmartKey, Mercedes-Benz integrates as an option Keyless Go; this feature allows the driver to keep the SmartKey in their pocket, yet giving them the ability to open the doors, trunk as well as starting the car without ever removing it from their pocket. The Keyless Go SmartKey was originally offered only in SmartCard format although the SmartKey Card has been discontinued in favor of the chrome SmartKey.
 

·
Registered
Joined
·
195 Posts
i was going to say the com-bar also, its in the rear roof area on top of the rear windshield... I have found alot of people have problems after tinting the windows.. esp if they use a Metal-based tint.. Most of the better tints are metal based.. like Lumar.. i had a episode where a womans car was tinted and she had real bad radio reception afterwards and her RF key functions were totally inop, but she still had the IR (in the door)... so to open the door she had to point the key at the door handle...

hey pepper.. they prob blew a fuse for the antenna (com-bar) amp... =)
 

·
Registered
2004 CLK 500
Joined
·
94 Posts
Discussion Starter · #8 ·
JayBell, you may be right. A blown fuse is the best explanayion I've heard. A new com-bar had just been installed. You'd think a new com-bar wouldn't need its software upgraded. The upgrade is what they charged to MB under warranty. Bet it was the fuse, though!

Pepper
 

·
Registered
Joined
·
21 Posts
My '05 CLK 500 {convertible} misbehaved in same fashion,
remote key works while pointing to the IR on passenger door only,
it'll open the trunk/boot from a close {3foot} distance,
nothing like the 150feet before this happened.
also the radio doesn't pick up but the strongest channel.
.
so the MB-tech told me its the radio-amplifier, that is located under the dashboard,
and I'm cautious about having the dashboard removed.
.
any suggestions on best plan of action?
If its the COM-BAR then is it necessary to go to the dealer as I live 100miles away.
.
Thanks in advance.
 

·
Registered
2016 GLE 400 4Matic
Joined
·
482 Posts
MB replace my smart key to the newer chrome style one and they replace the comm bar as well on my vehicle last year. Since then no problem. Except when I hold the button down on the smart key for all the window to go down and up It can not be more then 1 or 2 inches away from the sensor on the door handle. Is this normal?
 

·
Registered
Joined
·
6 Posts
The problem that I had was the remote would only work when pointed at the door and depending on how the sun is hitting the handle it would limit the distance. I went through the fuses associated with the remote door lock and removed and replaced and now I have the RF signal again. works now up to 50' away. there were a total of 5 or 6 fuses. one in the engine bay two in the dash/door area driver side. and two or three in the trunk. I don't actually know which one did the trick.
 

·
Registered
200clk cabrio 2009
Joined
·
6 Posts
hi I have a clk 200 2003 And my key only operates on infared i bought the car second hand and thought it was the key battery, it was not. My dealer (who seems to be trying to retire on my money) said that the areil was in the front windscreen and that the screen had been replaced with the wrong one and that the dash board would need to come out this sounds as though I wuld have no beer money for months. can you tell me where the fuses for the transmitter are as it sounds as though this will be the low cost option?
 

·
Registered
Joined
·
21 Posts
When I went to the dealer, they said the radio transmitter's were kaput. would need to take the dash out to replace them, then the radio & remote would work. I don't listen to the radio at all, and didn't like the idea of removing the dash.
I'd like to get it fixed but not with a rattle in the dash that requires multiple trips to the dealer. All the fuses looked ok, so all I did was remove & replace, but it didn't help.
Plz update when & how your's got fixed.
thx
 
1 - 14 of 14 Posts
Top