C-Class (W203) 2001-2007, C160, C180, C200, C220, C230, C240, C270, C280, C300, C320, C230K, C350, Coupe

2002 C240 Alarm problem NEED Help immediately!!

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old Feb 2, 2012 | 07:52 PM
  #1  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Angry 2002 C240 Alarm problem NEED Help immediately!!

Hello guys,

Been reading the forum for a while now, and now I need your help!

I have a 2002 Mercedes C240 Sedan. Pretty much stock.

Alright,

So, about two weeks ago, I was driving along and it gave me the warning that my hood was open. Pulled over, opened it, closed it, and it still happened. Over and over I would get this warning every once and a while. No big deal.

Then, it started. I park close to my apartment. At night, the alarm started going off. I would use the remote to lock it up, and sure enough..... over and over car alarm. So, everynight for the next week I would have to disconnect the battery. It didn't really happen during the day though (except I'm not usually near my car during the day, so i'm not sure).

So, I read the forums and some people say it's the key needing to be replaced. So, I took my spare key, Then I bought a new set of batteries, replaced them.

No car alarm for a couple of days. Now, i'm sitting at home, and for the past hour, it's been going off a few times every 20 minutes.



You guys have any ideas? I took it to a local repair guy, and he checked the sensors for the hood, they are all there and they are all working.

I need your help badly. Any suggestions?

Thanks for your time guys.
Reply
Old Feb 2, 2012 | 11:03 PM
  #2  
Ruination Fan's Avatar
Member
 
Joined: Jun 2010
Posts: 195
Likes: 0
From: San Diego
02 CLK430
Might be the alarm siren itself. They have a tendency to go off when the stand alone battery built in it goes bad.
Reply
Old Feb 2, 2012 | 11:30 PM
  #3  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by Ruination Fan
Might be the alarm siren itself. They have a tendency to go off when the stand alone battery built in it goes bad.

How hard is it to replace? What type of battery is it? Where is it located?
Reply
Old Feb 3, 2012 | 12:05 AM
  #4  
samaritrey's Avatar
Super Moderator
15 Year Member
 
Joined: Mar 2007
Posts: 5,295
Likes: 22
From: VA
THE C350
what about the hood switches going bad or loose connection?
Reply
Old Feb 3, 2012 | 01:06 AM
  #5  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by samaritrey
what about the hood switches going bad or loose connection?

According to the garage I brought it too, they checked all the hood sensors and they are all functioning. Is the hood sensor and the alarm two seperate issues? Or... when the car thinks the hood is open does the alarm sound?
Reply
Old Feb 3, 2012 | 08:43 AM
  #6  
Ruination Fan's Avatar
Member
 
Joined: Jun 2010
Posts: 195
Likes: 0
From: San Diego
02 CLK430
A faulty hood switch may cause it to go off(thinks somebody opened the hood after being locked). The alarm siren has a battery built into it, you can't get it seprate. Its located under the car to the area behind the Rf wheel liner, kind of under the passenger seat leg area, the liner part makes kind of a "L" shape.
Reply
Old Feb 3, 2012 | 09:14 AM
  #7  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by Ruination Fan
A faulty hood switch may cause it to go off(thinks somebody opened the hood after being locked). The alarm siren has a battery built into it, you can't get it separate. Its located under the car to the area behind the Rf wheel liner, kind of under the passenger seat leg area, the liner part makes kind of a "L" shape.

Ok, so you think my best bet is to have a tech replace all the hood sensors? If I took it to a MB Dealership, do you have any idea how much it would cost? I've never taken my car there out of fear of insane prices.

Anyway to just disconnect the alarm system completely? Like, make is so the alarm doesn't work (a fuse?)
Reply
Old Feb 3, 2012 | 09:21 AM
  #8  
Ruination Fan's Avatar
Member
 
Joined: Jun 2010
Posts: 195
Likes: 0
From: San Diego
02 CLK430
There is only one hood switch, and the siren would have to get replaced to fix. If you take it to a dealer they will be able to tell what caused the last 3-5 alarm activations, so it would be more accurate.
Reply
MB World Stories

The Best of Mercedes & AMG

story-0

Six Gift Ideas Your AMG Loving Dad or Grad Will Cherish

 
story-1

7 Craziest Things AMG Gas Ever Built

 Verdad Gallardo
story-2

New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know

 Verdad Gallardo
story-3

6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

 Verdad Gallardo
story-4

Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

 Verdad Gallardo
story-5

Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

 Verdad Gallardo
story-6

8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

 Verdad Gallardo
story-7

Flawlessly Restored Mercedes 190E Evo II Heads to Auction

 Verdad Gallardo
story-8

Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

 Verdad Gallardo
story-9

Mercedes EQS Gets A Major Update: Everything You Need to Know

 Verdad Gallardo
Old Feb 3, 2012 | 09:22 AM
  #9  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Alright. They replaced the hood switch, so I know that's not the problem. I guess my only option is to take it to a dealer. I just feel like i'm going to be paying out of the nose.
Reply
Old Feb 3, 2012 | 09:44 AM
  #10  
Glyn M Ruck's Avatar
Super Moderator
MBWorld Ambassador

 
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Does it still trigger if you turn the car lift switch off on the dash?
Reply
Old Feb 3, 2012 | 09:47 AM
  #11  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by Glyn M Ruck
Does it still trigger if you turn the car lift switch off on the dash?

Sorry, what do you mean? Unlock the car, sit in there and hold down the car lift switch and then lock the car back up and see if it goes off?
Reply
Old Feb 3, 2012 | 10:00 AM
  #12  
Glyn M Ruck's Avatar
Super Moderator
MBWorld Ambassador

 
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
You can deactivate the trembler switch in the alarm for towing purposes. The trembler sometimes goes sick.

If I were you I would pull the fender liner & replace the battery. Clean up everything while you are about it as corrosion sometimes sets into the alarm connectors etc..
Reply
Old Feb 3, 2012 | 10:11 AM
  #13  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by Glyn M Ruck
You can deactivate the trembler switch in the alarm for towing purposes. The trembler sometimes goes sick.

If I were you I would pull the fender liner & replace the battery. Clean up everything while you are about it as corrosion sometimes sets into the alarm connectors etc..

So before I get out of the car, I should just hold down the tow switch for a few seconds, and then it should be fine? Which battery are you talking about replacing?
Reply
Old Feb 3, 2012 | 10:32 AM
  #14  
LILBENZ230's Avatar
MBWorld Fanatic!
 
Joined: Jul 2008
Posts: 8,384
Likes: 800
2019 G70 6MT & 2022 Ford Maverick XL
All you have to do is press the anti-tow switch as you get out of the car. You don't have to hold it, at least not in mine. The light will briefly come on and then go out and it's good to go.
Reply
Old Feb 3, 2012 | 10:34 AM
  #15  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
Originally Posted by LILBENZ230
All you have to do is press the anti-tow switch as you get out of the car. You don't have to hold it, at least not in mine. The light will briefly come on and then go out and it's good to go.

Alright, I wouldn't mind doing that everytime I leave the car. That's better than replacing the alarm. I'll give that a try.
Reply
Old Feb 3, 2012 | 10:56 AM
  #16  
LILBENZ230's Avatar
MBWorld Fanatic!
 
Joined: Jul 2008
Posts: 8,384
Likes: 800
2019 G70 6MT & 2022 Ford Maverick XL
Well this will only determine if the tilt sensor is to blame. If it is, then the alarm won't keep going off. If it is not the tilt sensor then this won't fix it. The fact the car gave you hood open warnings is suspect.. even though you say they replaced the hood switch.
Reply
Old Feb 3, 2012 | 12:24 PM
  #17  
Bugler's Avatar
Thread Starter
Junior Member
 
Joined: Feb 2012
Posts: 16
Likes: 0
c240
I emailed my MB dealership, this is what they had to say on the issue:

"
I am responding to the email sent to us about your alarm going off. I think it sounds like it is the alarm siren itself. They tend to go off at random times due to corrosion of the wiring. I would need to get your VIN # of the vehicle to get you an exact price on replacement of the siren. Please send it to me when you have a moment since there are 3 different types of sirens for your specific vehicle. Once I have that information I will be able to proceed with somewhat of an estimate for you although it really should be diagnosed by one of our factory technicians first."


Ok. So, Here is my inquiry. Once he gives me the part number, i'll probably just end up buying it and trying it myself (depending on his quote price). Has anyone replaced it? Difficulty? Any links to a step-by-step? Where is it located (I know you said fender liner...but what is that?) ?

Thanks in advance guys. your really helping.
Reply
Old Feb 3, 2012 | 07:30 PM
  #18  
samaritrey's Avatar
Super Moderator
15 Year Member
 
Joined: Mar 2007
Posts: 5,295
Likes: 22
From: VA
THE C350
Star does tell you what the last 5 alarm triggers were so that would be interesting to see but it could be BS if the wiring is bad.
Reply
Old Feb 3, 2012 | 09:29 PM
  #19  
Glyn M Ruck's Avatar
Super Moderator
MBWorld Ambassador

 
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
There is a battery in the alarm unit with the siren behind the fender liner.
Reply

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -4. The time now is 02:39 PM.

story-0
Six Gift Ideas Your AMG Loving Dad or Grad Will Cherish

Slideshow: Six gift ideas your AMG loving dad or grad will cherish.

By | 2026-06-03 17:26:18


VIEW MORE
story-1
7 Craziest Things AMG Gas Ever Built

Slideshow: Sometimes AMG builds fast sedans. Other times, it builds twin-turbo V12 land missiles and six-wheeled off-road monsters.

By Verdad Gallardo | 2026-05-26 17:59:58


VIEW MORE
story-2
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know

Slideshow: Mercedes-AMG's new electric GT 4-Door Coupe trades combustion for software, synthetic noise, and more than 1,100 horsepower.

By Verdad Gallardo | 2026-05-20 20:08:15


VIEW MORE
story-3
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-4
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-5
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-6
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-7
Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-8
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-9
Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE