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Discussion Starter #1
Very strange issue. One day, my 2005 C240 wouldn't lock/unlock with the key fob / remote unless I was standing right next to the drivers side door. At any other distance, it wouldn't work.

Naturally, I grabbed my spare set - same problem.

Then I replaced both batteries - same problem.

Then, next time I got my service, I ordered a new set of keys - same problem.

I asked the technician, he was baffled and basically told me to just live with it.

So it is definitely a "reception" problem of the car, rather than something wrong with the keys. Has anyone seen this before?
 

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2002 C32 AMG
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The remote key has both IR, and radio signal control. To narrow it down, have you tried using the IR at a distance? Just point the front of the key directly at the IR receiver on the driver side door handle.
 

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RHD C200K Sport Coupe, RHD SLK-55, LHD SLK-350
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How's the reception on your radio? The remote shares the same antenna (unless I'm getting mixed up with the R171) - I'd look at the antenna and the splitter wiring - I'd bet one has come loose..
 

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Discussion Starter #4
Ah - the IR thing makes sense - its best when I point the key right at the IR reciever, but if I point it in the other direction, even close, it doesn't work.

My radio reception is fine... I'm going to take a look in the fuse boxes tonight to see if one may have popped, now that I know that IR/Radio are different systems.

Thanks for your help!
 

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UK-C200 is right, generally its the antenna for the radio and remote, its tied together. we call it a combi antenna, Its on the rear glass, but you have to pull the head liner down on some cars. I would go back to the dealer and complain. Was the the tech a new guy? tell him its most likely that combi antenna, comming from another techs
 

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Weak remote signal

Did you find a solution to this problem? What happened when you looked at the fuses? I'd hate to work around the headliner to find the antenna on the back window.
 

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Discussion Starter #7
All of the fuses were ok... and the radio reception works perfectly.

My solution has been using just the IR, close range by the driver's side door. Infuriating.

I'm not experienced enough to work around the back window, and the fact that the radio reception is fine makes me hesitant to get someone that knows what they are doing to charge me $1,000 for this.

I'll send a bottle of 18 year old scotch to anyone who can come up with a solution!!
 

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2002 C230 Sport Coup and 2006 ML350
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All of the fuses were ok... and the radio reception works perfectly.

My solution has been using just the IR, close range by the driver's side door. Infuriating.

I'm not experienced enough to work around the back window, and the fact that the radio reception is fine makes me hesitant to get someone that knows what they are doing to charge me $1,000 for this.

I'll send a bottle of 18 year old scotch to anyone who can come up with a solution!!
Seriously? I'll take McCallan's or Sherry finish Glenmorangie...

Now that being said, did you tint your windows recently?
What was the last thing done to your car just prior to the problem occurring?
Think hard...it might be something small....
 

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Ok, Here's what I did. It solved the problem.....for now.

Pulled fuses, 9,10 in the trunk panel and 21,22,32,33 in the fuse panel next to the drivers side. I looked to make sure they were intact and then put them back. I pried my fingers under the headliner at the back window and ran my fingers along the edge and found what I guess is the antenna wires for both the radio and the IR remote antenna. I moved the wires a bit and then tried the key.

It worked from 5' then 10' then i really pushed it and went accross the street.....about 75' and it still worked.

I'm not confident that it is a permanent fix but it's worth a shot.

Let me know if it works for you. :)
 

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2002 C32 AMG
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Just a little side note to add... The remote key works best if unlock/lock is held for at least one second. For some reason a quick click will work close up, but not futher away. This is when you need to hold the button down. :)
 

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Ok, Here's what I did. It solved the problem.....for now.

Pulled fuses, 9,10 in the trunk panel and 21,22,32,33 in the fuse panel next to the drivers side. I looked to make sure they were intact and then put them back. I pried my fingers under the headliner at the back window and ran my fingers along the edge and found what I guess is the antenna wires for both the radio and the IR remote antenna. I moved the wires a bit and then tried the key.

It worked from 5' then 10' then i really pushed it and went accross the street.....about 75' and it still worked.

I'm not confident that it is a permanent fix but it's worth a shot.

Let me know if it works for you. :)
okay i tried doin that and still nothing ...
 

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Thanks for the thread. I need to try something to get ALL windows up or down at the same time. For some reason it just works when it wants to. Perhaps my wires need to be jiggled.:D
 

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2002 C230K Coupe, C7 package, pano roof, auto, ASP pulley, NGK IR IX plugs
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I have the same problem with my system... its freakin annoying!! It's a crap shoot whether or not it will work properly or not. The messed up thing about it though, when it's hot/humid and sunny out, around midday, it wont work at all. But it does seem to work fine at night or when it's cool out but most times I have to use my damn valet key. Awesome..isnt it? I drive a benz and i can hardly even lock/ unlock my doors.
 

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95" W124/ E220 MasterPiece and 01" W210/ E200 KOMPRESSER
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Bad reception comes from the rear window sealing process. The culprit is the metal clips on the window. These "clips" are clipped on the pane frame...but this frame (car body as well) comes with "paint primer." The primer interferences the reception of radio signal when installing the rear glass pane. Clips cannot send out signal to the combi reception amplified antenna receiver (bad contact with metalic body, but with contact with primer), thus bad reception. Stealers recommend a change of your window pane...but wise you know how to deal with that.
 

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hey yall i just had the same issue with my 05 C240 4Matic. i went ahead and started to think it was the IR sensor. seen on here one said to check fuse's 21,22,32,33 on the drivers side and fues's 9,10 in the trunk. so i did and load and behold i found a possible issue fuse number 8 in the trunk was blown its a 7.5 fuse i went to replace it with another 7.5 fuse and it blew the moment i replaced it. so being a engineer and all i put a higher rated fuse to replace the mr. number 8 fuse in the trunk with a 30 fuse and it did not blow on contact went pulled the key fob out and now i have better signal than i ever had i can walk out to 100' and still lock unlock open the trunk and set the panic off which is annoying as hell plus one i have never been able to do was roll up and down the windows i hope this helps some of yall. plus if you love your benz as much as i do and love to wax it never never ever get wax near the drivers side door handle wax can degrade your IR sensor and cause problems with the window function hope this helps yall cheers mates
 

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216 with everything. 2002 SL500 with everything. 2009 SL500 with everything.
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Fuse 8 blows because the alarm siren goes short circuit, it does not blow because of the antenna amp. replace or disconnect the siren.
 

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2002 C240 Auto (Hijacked by criminals)
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Replacing a 7.5 amp with a 30 could result in overloading wiring, which in turn could result in a fire. If the siren is short circuited and the alarm goes off for any long period of time, you may lose your car. Better to fix the cause than the symptom.
 

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(sold 99 ML320) + 05 C240 4matic
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Hi
I've similar issue with the wife's 05' c240 4matic
IR works fine in close proximity
Antennae is issue AND she did have tints just done.

I'd appreciate your comments - dealer wanted to replace the rear Sam, and I've already paid them too much ($300) just to chase the problem with 0 results.
 

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CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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The tint shop probably disturbed the amp where it mates to the glass. It's aver expensive repair - around $2K.
 
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