1999 E300 Key would not turn...then it did - PeachParts Mercedes-Benz Forum

jay_bob · #7 01-30-2015, 10:26 AM

The W210 electronic steering lock, for the uninitated, uses the "smart key". There are 3 components to the system:
- an RF-based system that transmits the unlock/lock/trunk/panic commands to the car. This is how the car locks and unlocks.
- and IR based system that transmits the above commands to the car. This is used for the "convenience" features, like opening all the windows if you hold down the "unlock" button.
These 2 features use the 2 CR2025 lithium batteries inside the key.

The third element is the DAS authorization chip. This is what unlocks the steering (and also lets the rest of the car function). It is an RFID chip that is inductively powered from the transmitter in the key switch. It has nothing to do with the lithium batteries in the key. I believe this is actually the same device that they use to "microchip" your dog or cat. Not 100% sure on MB but I know for a fact that is what Honda uses for the "immobilizer" system.

When you insert the key, the DAS system queries the RFID chip, and if the DAS accepts the stored serial number in that key's chip, then it allows the steering wheel to unlock (the 'zzzt' sound). From my experience, this locking system does not seem to have the same problem as mechanical steering locks, that can get bound up if the wheel is turned off center or something is putting pressure on the lock.

This locking mechanism apparently consumes energy, because if you put the key in the lock, but don't start the car, it will eventually time out and re-lock the steering wheel. In order to unlock the wheel, you have to take the key out and reinsert it. This is mentioned in the owner's manual.

One other thing the manual cautions about (and my Honda's manual says the same thing) is to not have multiple RFID keys for different cars on the same ring. I have personal experience with this, since I am fortunate enough to have 2 late model MBs with the Smartkeys. I have never had a problem with the 2 keys interfering with each other, either with the MB system, or the Honda system (when I had 2 Hondas) or if you have an MB and Honda key on the same ring. Only problem I have is if I put the wrong MB key in the car. The 210 just sits there and won't unlock. The 164 puts a message on the console that this is not the correct key.

All that said, I would be looking at my K40, but as TJTS1 says, just reflow the joints.