Iggier

Please help me solve this mystery with my 2005 C240 (Orion Blue ).

Arrive at destination >> place transmission in PARK >> turn vehicle off >> apply parking brake >> remove smart key from ignition >> open driver’s door >> exit vehicle

And here’s where it’s inconsistent:

The majority of the time, when exiting the car (opening the driver’s door) the passenger door will also automatically unlock. This is very convenient since I usually walk around the car to retrieve stuff from the passenger seat.

However, frequently, the same sequence of events does not automatically unlock the passenger door. So I find myself, usually hands full, fumbling with the smart key to unlock the opposite side of the car.

I simply cannot figure out why the passenger door unlocks sometimes but not always and it’s driving me crazy. I really want it to always unlock when exiting the vehicle. Maybe there’s some type of countdown mechanism – if I don’t open the driver’s door soon enough after turning off the engine the passenger door won’t unlock? Maybe there’s a relationship to setting the parking brake?

My smart key is set to selective (once to unlock driver’s side, twice for all doors) and automatic central locking (over 9mph) is enabled.

Despite searching the threads and reading and rereading the owner’s manual, I’ve found nothing.

DriveABenz

I too used to get frustrated by the apparent randomness of the doors unlocking, but paid attention for a week while getting into and out of my car. I haven't read the manual for this specific issue, but I've found the following to happen:

1. If I unlocked only the driver's door with the smartkey, when I reach my destination and open the driver's door, only that door unlocks.

2. If I unlocked all doors with the smartkey, when I reach my destination all the doors unlock the moment I open the drivers door.

I too have my car set exactly the same way you do for the unlocking sequence

Iggier

Thanks DriveABenz for your reply. I'm going to test out your observations. If it works the way you've explained (doors unlock based on doors opened with smartkey) then methinks that resetting the smartkey to global instead of selective locking would solve the problem?

diamondblak05

I too am annoyed by this inconsistent unlocking of the doors. During my last service, I asked the SA about it and he said it depends on how fast or slow I pull on the door handle. Well, that didn't make sense because I tried it when I got home with varying speed at pulling the handle. Still same inconsistent result. There is nothing about this feature in the manual. How fustrating!

Iggier

Actually, I had considered this when first trying to figure out why sometimes all the doors unlock, and other times only the driver's door. But...in trying all variations of "timing" before engaging the door handle, my results are the same as yours - INCONSISTENT

TA-9FF

Seems like SmartKey ain't so smart.

rrpnow

that makes sense though... if you only opened your driver's side door for a reason, then it makes sense when you want to exit your vehicle the same should happen...