Doors unlock all by themselves while driving???
Thread Starter
Junior Member
Joined: Jun 2007
Posts: 18
Likes: 0
From: MI
2006 C230; 2012 R350
Doors unlock all by themselves while driving???
I have a 2006 C230 that has around 26,000 miles on it currently. A few weeks ago, my doors began spontaneously unlocking while driving around.
I took it to a local dealer and they were unable to duplicate the problem. They said they found no codes and that the crash sensor and door sensors were not the problem. Just the doors were unlocking - no lights or other warnings came on when the doors unlocked.
I wasn't sure what was causing it, so I started searching and found one or two obscure references online. The one that was most intriguing was that this happened to others before that had something in their trunk. I folded down the driver side rear seat, started up the car, sat in the passenger side rear seat, and with the doors closed and locked, I began tapping my hand around the trunk area by the driver side SAM (fuse/relay block). Sure enough after a couple taps, the door locks popped right open. I locked them and tried again. Yep, they unlocked again. One more time just to make sure. Every time I tapped the SAM, the doors unlocked.
Apparently, when I had stuff in my trunk that slid around and hit the SAM, it was doing the same thing - causing the door locks to intermittently and spontaneously unlock while driving.
Know, does anyone have any idea on why this does this? Is it a known issue that I will just have to deal with, or do you think it is a defective SAM, or maybe a loose connection? I can't get it back to the dealer for a couple weeks. If it for some reason this is just the way this is going to be, I certainly don't want to waste the time taking it back to the dealer.
I took it to a local dealer and they were unable to duplicate the problem. They said they found no codes and that the crash sensor and door sensors were not the problem. Just the doors were unlocking - no lights or other warnings came on when the doors unlocked.
I wasn't sure what was causing it, so I started searching and found one or two obscure references online. The one that was most intriguing was that this happened to others before that had something in their trunk. I folded down the driver side rear seat, started up the car, sat in the passenger side rear seat, and with the doors closed and locked, I began tapping my hand around the trunk area by the driver side SAM (fuse/relay block). Sure enough after a couple taps, the door locks popped right open. I locked them and tried again. Yep, they unlocked again. One more time just to make sure. Every time I tapped the SAM, the doors unlocked.
Apparently, when I had stuff in my trunk that slid around and hit the SAM, it was doing the same thing - causing the door locks to intermittently and spontaneously unlock while driving.
Know, does anyone have any idea on why this does this? Is it a known issue that I will just have to deal with, or do you think it is a defective SAM, or maybe a loose connection? I can't get it back to the dealer for a couple weeks. If it for some reason this is just the way this is going to be, I certainly don't want to waste the time taking it back to the dealer.
MBWorld Fanatic!
Joined: Jun 2003
Posts: 9,498
Likes: 4
From: San Diego, CA & San Jose, Costa Rica & Stuttgart, Germany
1959 220S / 1979 230 G / 2002 A210 AMG / 2003 C320 SC / 2004.5 C320 SS / 2005 ML350 SE / 2008 smart
take it to the dealer, and repeat that same trunk/SAM scenario.
MB may not even know about that "bonus feature".
MB may not even know about that "bonus feature".
Thread Starter
Junior Member
Joined: Jun 2007
Posts: 18
Likes: 0
From: MI
2006 C230; 2012 R350
I do want to take it in AGAIN, but only IF I can confirm that this is truly an isolated problem with my vehicle that can be corrected by replacing the SAM in my vehicle or finding the real problem causing this. I saw a few other posts about similar problems others have had with various years of C's, so I am finding it hard to believe that I am some kind of genius that single handedly figured this "bonus feature" out, and that it only happens with my C.
In other words, if this is just what is going to happen, even with a new SAM, I'd rather save myself the time and hassle of being without my vehicle for 2 days in service, and just do my best to minimize the circumstances that cause the problem to happen in the first place (now that I know what is causing it). Kind of like the old joke - a guy goes to the doctor and complains that it hurts when he puts his arm over his head. So the doctor tells the man not to put his arm over his head.
Last edited by kevins_garage; Jun 27, 2007 at 11:10 PM.
Thread Starter
Junior Member
Joined: Jun 2007
Posts: 18
Likes: 0
From: MI
2006 C230; 2012 R350
Hence the reason I am trying to take whatever reasonable steps I can to verify if this is a real problem (i.e. defective SAM?), or if this is just the way it was designed (i.e. possibly the impact on the SAM causes the door lock relay to bounce and unlock the doors and that's just the way it's going to be?)
I have a week or so to see what I can find out before I will have the time to get it back into the dealer. Unfortunately, the dealers near me are only open M-F 8-5 and I leave for week way before that and don't get home until way after. I don't want to drop it off after hours only to waste another 2 days because the tech/s couldn't duplicate the problem on their own or just to have it turn out that the doors will always unlock if the SAM is impacted. [sigh]
Trending Topics
Member
Joined: Feb 2007
Posts: 110
Likes: 0
From: vancouver canada
2001 c240, 65 MG Midget...5.0L V8
it happened to me once before, it never happened again but now that i think about it i did have some loose stuff in the trunk so it makes sense,my SAM is brand new so i think it's just a problem with the design or something.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
MBWorld Fanatic!
Joined: Jun 2003
Posts: 9,498
Likes: 4
From: San Diego, CA & San Jose, Costa Rica & Stuttgart, Germany
1959 220S / 1979 230 G / 2002 A210 AMG / 2003 C320 SC / 2004.5 C320 SS / 2005 ML350 SE / 2008 smart
just a hunch....
but I would type in the letters: S A M
into the "Search" function...
it's amazing what you might find !
but I would type in the letters: S A M
into the "Search" function...
it's amazing what you might find !
MBWorld Fanatic!
Joined: Nov 2003
Posts: 1,455
Likes: 1
From: Colorado Springs
E55 AMG Black on Carlsson 1/6 EVO
MBWorld Fanatic!
Joined: Jun 2003
Posts: 9,498
Likes: 4
From: San Diego, CA & San Jose, Costa Rica & Stuttgart, Germany
1959 220S / 1979 230 G / 2002 A210 AMG / 2003 C320 SC / 2004.5 C320 SS / 2005 ML350 SE / 2008 smart
you're welcome !
Thread Starter
Junior Member
Joined: Jun 2007
Posts: 18
Likes: 0
From: MI
2006 C230; 2012 R350
Sorry for not posting a follow up in a while, but apparently I beetched and complained enough about this issue that MBUSA has now issued a TSB or other notification to dealers abotu this issue.
MBUSA claims it is due to loose items in the trunk banging into the SAM on the drver side rear of the trunk and causing it to "think" there has been an accident, thereby signalling all the doors to unlock. What an effin joke!
Their suggestion to me was to secure anything in my trunk so it isn't allowed to move around. Whatever? Last I checked, there weren't any tie downs or anything else to secure much of anything.
If you want to duplicate it yourself, open the trunk, start your car and get out, closing all doors. Flip the lock on the decklid so the car thinks the trunk is locked, then hit the area in the trunk where the SAM is 2-3 times or so. You don't have to punch it hard, but it does need a pretty good tap. The locks opened everytime I did that.
MBUSA claims it is due to loose items in the trunk banging into the SAM on the drver side rear of the trunk and causing it to "think" there has been an accident, thereby signalling all the doors to unlock. What an effin joke!
Their suggestion to me was to secure anything in my trunk so it isn't allowed to move around. Whatever? Last I checked, there weren't any tie downs or anything else to secure much of anything.
If you want to duplicate it yourself, open the trunk, start your car and get out, closing all doors. Flip the lock on the decklid so the car thinks the trunk is locked, then hit the area in the trunk where the SAM is 2-3 times or so. You don't have to punch it hard, but it does need a pretty good tap. The locks opened everytime I did that.
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,265
Likes: 169
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
I had this problem, but they replaced the door switches, the ones that make the lights go on when you open the door.
Then again, my car has had just about every electronic module,
harness, sensor, and wire replaced under warranty.
Stick it to the man! Errr...the dealer.
Now I seem to have a reliable vehicle (fingers crossed)
with the exception of the coil packs, which is why I keep a spare in the car.
120K miles.
I'd post my repair history but I'd be dead by the time I finished typing.
Get EVERYTHING you can under warranty. You have a 1st year car in the sense of the new 6 banger.
Then again, my car has had just about every electronic module,
harness, sensor, and wire replaced under warranty.
Stick it to the man! Errr...the dealer.
Now I seem to have a reliable vehicle (fingers crossed)
with the exception of the coil packs, which is why I keep a spare in the car.
120K miles.
I'd post my repair history but I'd be dead by the time I finished typing.
Get EVERYTHING you can under warranty. You have a 1st year car in the sense of the new 6 banger.
Super Member
Joined: Oct 2007
Posts: 537
Likes: 2
From: Charlotte, NC
2013 S550, CLS500, ‘03 SL500, “92 190E Sportline
Got in my 2003 C230 Sedan, and the door open indicator came on, the rear left door was open. I reach back, close it, and it opens again, all by itself. The door open indicator kept coming on and the door opened while I was driving. It didn't fly open, but I'm afraid of that happening lol. After restarting the car it didn't occur, but I wonder what caused that.
Junior Member
Joined: Mar 2008
Posts: 60
Likes: 0
2001 C240
My C240's doors unlocked by themselves while driving just as the original poster described about 2 weeks ago for the first time, after I hit a large depression in the road due to the asphalt settling after the electric utility did work under the street. This thread describing how the SAM reacts to large sudden impacts of force answers my question of why this happened.
MBWorld Fanatic!
Joined: Nov 2007
Posts: 2,078
Likes: 4
From: NYC
2012 C300 4Matic
Yep, there is a crash sensor in the rear SAM. The normal behavior is supposed to be that during an impact that sensor unlocks the doors, turns on the interior lighting (not sure if this is only at night). And turns on the hazard lights. I find it strange that only the doors are unlocking. Maybe there is a sensor in the front sam for the hazards and interior lighting?!
Senior Member
Joined: Jul 2008
Posts: 267
Likes: 0
05 c230 kompressor
yo!!! i had that same exact problem happen to me. it stopped doing after i took my car in for srs light problem along with seatbelt warning that kept flashing as if someone was sitting on my passenger side. as soon as i slowed down even when i was close to home that doors would unlock right there and then. i explained it to the dealership and they thought i was crazy. but it stopped doing it.
