Failing Remotes
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Member
Joined: Jan 2014
Posts: 165
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From: Central California
05 CLK320 Cabriolet W209 & 2011 BMW X3
Failing Remotes
I own a 2005 CLK320 Convertible and both my remotes are getting equally weaker and weaker. Now I have to hold the remote flush with the door handle sensor for the car to respond. I changed the batteries in both remotes and no improvement. The car battery is fine and starts the car right up. I would hate to go to the dealer for new ones when there might be some other issue. I am guessing the dealer will charge me around $180 to $200 for each remote. The car will be 9 years old in May. I guess nothing lasts forever.
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Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
At my house, if I take my car key and press the unlock button from the master bedroom, the car, which is in the garage, will unlock. At my house, the master bedroom is upstairs at the rear of the house. The garage is at the front of the house.
How do I know this has nothing to do with the reader in the door handle? Because I can't use the key to open or close the car’s windows and sunroof from the master bedroom and an infrared signal is required to do that. As far as I know, it is impossible for the infrared signal in the key to pass through the walls and floors of the house and be picked up by the reader in the car’s door handle – yet the car still unlocks. I say “as far as I know” because I don’t have a degree in Electrical Engineering. Someone with a double-E may disagree and tell me modern IR signals are completely different. I welcome their correction. Based on what I think I know, infrared signals require a line of sight to function, which I don’t have from my master bedroom.
Confused? A modern Mercedes Benz smart key uses an infrared sensor and a radio frequency sensor. According to the owner's manual, the car has an infrared sensor in the door handle. Trust me, the radio frequency sensor is in the rearview mirror. When someone says the keys don't work "from a distance", either there is RF interference, the signal from the key is weak, or the radio frequency sensor is not seeing or recognizing the signal. There may be other issues, but dems 'da common ones.
There was a time when 500 posters would have jumped on this thread. The W208 faithful are a dying breed.
How do I know this has nothing to do with the reader in the door handle? Because I can't use the key to open or close the car’s windows and sunroof from the master bedroom and an infrared signal is required to do that. As far as I know, it is impossible for the infrared signal in the key to pass through the walls and floors of the house and be picked up by the reader in the car’s door handle – yet the car still unlocks. I say “as far as I know” because I don’t have a degree in Electrical Engineering. Someone with a double-E may disagree and tell me modern IR signals are completely different. I welcome their correction. Based on what I think I know, infrared signals require a line of sight to function, which I don’t have from my master bedroom.
Confused? A modern Mercedes Benz smart key uses an infrared sensor and a radio frequency sensor. According to the owner's manual, the car has an infrared sensor in the door handle. Trust me, the radio frequency sensor is in the rearview mirror. When someone says the keys don't work "from a distance", either there is RF interference, the signal from the key is weak, or the radio frequency sensor is not seeing or recognizing the signal. There may be other issues, but dems 'da common ones.
There was a time when 500 posters would have jumped on this thread. The W208 faithful are a dying breed.
Senior Member
Joined: Jun 2013
Posts: 287
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From: New Hampshire
Magma Red W208 55 AMG, W203 C230 Kompressor Sedan 6speed M/T, W220 S500
I have to agree with Markus about how the key functions. I would have maybe tried to help with the op if I had known anything about the 2005 model. Unfortunately my knowledge is limited to the w208 and w210.
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From: Washington, DC Metro Area
Currently: 2019 E450 AWD, Previous: 2002 CLK55 Cab
Markus interesting. My will unlock the doors from a distance of maybe ten feet with line of sight. No windows rolling down or any of that. Fresh batteries all around. Two questions: are the transmitters in the newer keys stronger? Second, I pulled the Command HU and replaced it with an aftermarket Alpine unit. Would the removal of the command hu have any effect on rear view mirror sensor? It seems like there are a few.command interlinked features in there. Thanks.
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Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
With the smart key within line of sight of the infrared sensor in the door, push and hold the unlock button. That will unlock the doors, roll the windows down, and open the sunroof. Holding the lock button will lock the doors, roll the windows up, and close the sunroof. The button must remain held while the windows and sunroof are in motion and the key's infrared nose piece must be pointed at the sensor. Releasing the button will stop the windows and sunroof in their current position. I have original keys (with new bodies) and this works on my car.
I too have replaced the original HU with an Alpine deck and my keys still work. *I think* the IR sensor in the door handle is independent of the RF sensor in the rear view mirror - although I've never tried to test it. I've a fair amount about COMAND units and I don't see where they impact the RF or IR key signals. I'm not saying they don't, I'm saying I've never read anything about it.
I too have replaced the original HU with an Alpine deck and my keys still work. *I think* the IR sensor in the door handle is independent of the RF sensor in the rear view mirror - although I've never tried to test it. I've a fair amount about COMAND units and I don't see where they impact the RF or IR key signals. I'm not saying they don't, I'm saying I've never read anything about it.
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Thread Starter
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Joined: Jan 2014
Posts: 165
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From: Central California
05 CLK320 Cabriolet W209 & 2011 BMW X3
After reading these posts I went in the garage and stood about 5 feet away and the car would not respond at all to either of my remotes with fresh batteries. I then stood next to the drivers side window and pointed the remotes directly at the rear view mirror through the closed window. Again neither remote worked the car. I then held each remote flush to the little square in the drivers side handle. Again no response from either remote. Should I get the rear view mirror diagnosed?
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MBWorld Fanatic!
Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
Personally, I'd drop the car at the dealer and let them figure it out. Although the DAS3 key system is complex, a good dealer should be able to have it working in no time. Besides you get their loaner while you wait (although I'm no fan of the CLA). 
I hope that helps
- Marcus
I hope that helps
- Marcus
Thread Starter
Member
Joined: Jan 2014
Posts: 165
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From: Central California
05 CLK320 Cabriolet W209 & 2011 BMW X3
I am pretty sure I resolved my failing remotes problem myself. On Ebay I bought a copy of MB Service Repair Manual DVD: http://www.ebay.com/itm/201011500928...84.m1497.l2649 for $11.90 which has tons of info on it. It took me over 3 days to find what I was looking for. "Remote Control Key Function" it said to hold down buttons 1 & 2 (Lock & Unlock) for >5 sec until the red light blinked. This changed the remote functions from Selective to global. Now I can stand over 5 feet away from my car to lock & unlock the car. I am so happy I could just SH*T!!!!!!!!!!! I just saved myself a huge repair bill!!!
MBWorld Fanatic!
Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
Glad it worked for you. However, the global / selective setting is supposed to simply determine whether both doors and the trunk are unlocked with one push of the key, or two. It's not supposed to have anything to do with transmitter distance. The feature is documented in your owners manual - pages 95 & 96 for the 2005 W209 manual and 29 & 30 for the 2002 W208 manual. If you don't have an owner's manual, Mercedes-Benz keeps a 15 model year digital supply and offers them for free at MBUSA.com
Good find on the $10 service manual DVD. I'll update the other thread so people can stop looking for the WIS.
Good find on the $10 service manual DVD. I'll update the other thread so people can stop looking for the WIS.
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Joined: Jan 2014
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2004.7 C180 Kompressor, BMW X5, Chevrolet Camaro LT, Mercedes S, Cesna 152.
I am pretty sure I resolved my failing remotes problem myself. On Ebay I bought a copy of MB Service Repair Manual DVD: http://www.ebay.com/itm/201011500928...84.m1497.l2649 for $11.90 which has tons of info on it. It took me over 3 days to find what I was looking for. "Remote Control Key Function" it said to hold down buttons 1 & 2 (Lock & Unlock) for >5 sec until the red light blinked. This changed the remote functions from Selective to global. Now I can stand over 5 feet away from my car to lock & unlock the car. I am so happy I could just SH*T!!!!!!!!!!! I just saved myself a huge repair bill!!!
Smart Man!
Thread Starter
Member
Joined: Jan 2014
Posts: 165
Likes: 8
From: Central California
05 CLK320 Cabriolet W209 & 2011 BMW X3
Well it looks like my resetting the remotes from selective to global did not work as expected. Last evening I was amazed about the improvement in operating distance. This morning it was back to its old tricks. I had to hold the fob right up to the little receiver window in the drivers door handle to unlock the car. The only improvement was now the car locks & unlocks better from the passenger side. I don't have to hold the fob up to the little receiver window in the passenger handle. My best guess is that the sensor in the drivers door handle needs replacement or repair. Dealer here I come.
