2004 C320 - Key Fob Issues
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MBWorld Fanatic!
Joined: Mar 2015
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From: Sacramento, CA
2018 GLC300 4Matic; 2008 ML550 4Matic; 2004 C320
I replaced my siren shortly after I bought my car 6 years ago. I don't know when it failed and how long I should expect the one I installed to survive. It will be interesting to find out whether the sirens become available again. I may need to bypass mine when it fails at some future date. I've read the component that causes the failure is a battery inside the siren. I think I saw a post showing how to dissect the siren and replace the battery with a generic one.
The siren is in the passenger-side front wheel well and the location exposes it to moisture. Mine was corroded and I didn't attempt to dissect it to see whether I could replace the battery. The next time I'm at the "pick and pull" I may grab one for possible future use.
I don't plan to visit my dealership service department for anything other than a recall. (I've had three recalls. One for the airbag and two for the sunroof.) I think they are primarily interested in warranty work and prefer to avoid working on older cars.
The siren is in the passenger-side front wheel well and the location exposes it to moisture. Mine was corroded and I didn't attempt to dissect it to see whether I could replace the battery. The next time I'm at the "pick and pull" I may grab one for possible future use.
I don't plan to visit my dealership service department for anything other than a recall. (I've had three recalls. One for the airbag and two for the sunroof.) I think they are primarily interested in warranty work and prefer to avoid working on older cars.
I will not mess with this siren, don’t need it for anything. Not that anyone is trying to steal a 20 year old car and if they do, half of America won’t be able to drive a manual anyhow.
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Joined: Jul 2017
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From: Richmond, VA Metro Area
2005 C230 Sport Sedan-6 Speed Manual
Her ability to drive a car with a manual transmission also impressed the young man who is now her husband. But that is a story for another time.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2015
Posts: 1,975
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From: Sacramento, CA
2018 GLC300 4Matic; 2008 ML550 4Matic; 2004 C320
An additional benefit - especially if this car is your college-student son's car is that most of his peers cannot drive it either. I bought a 2006 Civic with a manual transmission for my daughter during her last year of high school. She took it to college with her. She later told me that her friends would ask to borrow her car. When she asked them if they could drive a stick, they all said "No." As she explained, she didn't want to lend them the car, but their lack of ability let her avoid being the "bad guy." Since any accidents her friends might have would have been on my insurance, I am pleased with that outcome.
Her ability to drive a car with a manual transmission also impressed the young man who is now her husband. But that is a story for another time.
Her ability to drive a car with a manual transmission also impressed the young man who is now her husband. But that is a story for another time.
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Joined: Sep 2024
Posts: 2
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From: Somers,CT
2002 Mercedes C240 (W203)
I am glad i found this thread....i have a 02 c240 (w203) same exact issues i replaced the siren myself which fixed the duse issue but still can lock/unlock, the ir works fine when it feels like it when i scan it to see the last 4 alarms its always me opening the door with physical key.... i will have to go to stealership as well.... my question is how expensive was it to have the AA replaced?
Thread Starter
MBWorld Fanatic!
Joined: Mar 2015
Posts: 1,975
Likes: 265
From: Sacramento, CA
2018 GLC300 4Matic; 2008 ML550 4Matic; 2004 C320
I am glad i found this thread....i have a 02 c240 (w203) same exact issues i replaced the siren myself which fixed the duse issue but still can lock/unlock, the ir works fine when it feels like it when i scan it to see the last 4 alarms its always me opening the door with physical key.... i will have to go to stealership as well.... my question is how expensive was it to have the AA replaced?
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Joined: Dec 2024
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From: Belfast Ireland
I hear crickets....chirp, chirp.
The only thing you can check is the antenna amplifier where I told you to press on the headliner. It is attached to the rear glass with double sided tape and the soft conductive contacts press up against the antenna lines on the glass. The amplifier sometimes will become loose and lose contact. Last I heard, MB no longer sells them, but in theory could be repaired with (new) double sided tape.
Any other diagnosis will require Xentry/DAS and a knowledgeable MB tech who knows these older cars.
No, I'm not flying out to Cali!
https://www.google.com/search?q=w203...w=1536&bih=809
The only thing you can check is the antenna amplifier where I told you to press on the headliner. It is attached to the rear glass with double sided tape and the soft conductive contacts press up against the antenna lines on the glass. The amplifier sometimes will become loose and lose contact. Last I heard, MB no longer sells them, but in theory could be repaired with (new) double sided tape.
Any other diagnosis will require Xentry/DAS and a knowledgeable MB tech who knows these older cars.
No, I'm not flying out to Cali!
https://www.google.com/search?q=w203...w=1536&bih=809
Does a key suddenly stop working for no reason.
The car is e220, 2007 - no problem before this.
A couple of weeks ago my key stopped working. I got a lift 50 miles home to pick up the spare which works fine. The insurance company said they will not replace the key fob as it is only covered for damage and they class this as "coming to the end of its life" ,
My view was it was damaged (I was at the beach in middle of winter) , but as I didn't tell them I dropped it or it fell in water they won't cover it.
Do MB keys not last the life of the car - I know it is 2007 - but my c class is 1997 and I've never heard of any issue with keys getting old .....
any ideas ??
Member
Joined: May 2010
Posts: 89
Likes: 12
2003 E320 4matic wagon
Some follow-on things learned:
My key fob was kaput as well after a dead car battery (car sat for 2 years unused, then I bought it).
interestingly enough the radio only received 1 channel which I though was odd. Turns out Fuse #8 in rear trunk area interfaces with both. Replaced fuse with 7.5A, reprogrammed key fob by inserting key, turning to second click position, depressing door open & lock buttons at same time for 6-8 seconds then removing. Was afraid it was the receiving antennae but turned out to not be the case. Just wanted to share my experience on this issue.
Thank you to all who posted #8 fuse location - spot on!
My key fob was kaput as well after a dead car battery (car sat for 2 years unused, then I bought it).
interestingly enough the radio only received 1 channel which I though was odd. Turns out Fuse #8 in rear trunk area interfaces with both. Replaced fuse with 7.5A, reprogrammed key fob by inserting key, turning to second click position, depressing door open & lock buttons at same time for 6-8 seconds then removing. Was afraid it was the receiving antennae but turned out to not be the case. Just wanted to share my experience on this issue.
Thank you to all who posted #8 fuse location - spot on!
