Electric Steering Lock (ESL) Problems in W204, W207, W212

[domwildone]

Various Mercs, like my W204 2007 model and also W207, W212, etc. suffer from not starting due to failure of a US$3.57 Chinese motor, which pushes the pin in and out for the lock of the steering. That repair then costs AUS$2,000 plus towing, great! A case of German over-engineering to lock the steering wheel as it is no longer done in later models. Worse, if the rumours are correct, the NEC security chip on the ELS records the number of starting attempts with this slowly dying motor and then decides electronically to block any further attempts of "stealing". This means a trip to a locksmith to mate the ELS with ignition lock and key. After having changed that motor, I would like to test the ESL (Electric Steering Lock) and I have a schematic for the four electric pins, which may not even be correct:

Both top pins at the rectangular end of the ELS junction box go to +12V
Bottom LH pin goes to GND
Bottom RH pin goes to the "K-LINE" of the EZS or ignition lock

Provided those pins are marked correctly, what sort of a voltage would go from the ignition lock to the ESL via the K-LINE, either fed from the CAN-EL bus or the CAN-EH bus.
Is that a 2.5VDC control signal or is it also a 12V control signal on a CAN bus to start the action? Would it only be a pulse?

The NEC chip must have the logic to drive the motor one way to pull the steering lock in and stop when the limit switch says so and turn the motor the other way to push the lock out and stop at the limit.

Anyone out there with a black belt in Mercedes electrickery? Thanks.

 

[John Laidlaw]

@JohnnySBC

 

[Marxs1]

Hi Dom, I ended up putting the emulator on mine, however you need to find people who can program it. I found a locksmith who installed and programmed it all, about a quarter of the cost of the dealers to repair the original.
The best thing about the emulator is that this problem is over forever and I will not be stuck up the supermarket again.

 

[mersum1es]

I have access to wiring diagrams but that would not answer your quations about control signals, I am afraid.

Just for note; buying 20€ replacement motor (instead of 3€) and replacing it will prevent you facing same excercise again after few years... there are couple of good threads how-to-DIY.