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2007 C220 CDI Avantgarde W204
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Discussion Starter #1
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 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.
 

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Registered
2005 CLK320
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493 Posts
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 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.
The k-line is a data line you need MB SDS software if you want to test it.
If you just replaced the motor you should be good otherwise the ezs needs to be programmed to the car.

Sent from my SAMSUNG-SM-G870A using Tapatalk
 

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Registered
2007 C220 CDI Avantgarde W204
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91 Posts
Discussion Starter #3
The k-line is a data line you need MB SDS software if you want to test it.
If you just replaced the motor you should be good otherwise the ezs needs to be programmed to the car.

Sent from my SAMSUNG-SM-G870A using Tapatalk
Thanks, Paul. Please tell me if SDS means "Star"? I have an iCarsoft MB2 diagnostic, but that one only still gives me the A25646 "Implausible signal received" error message. Problem is, my ESL with the new motor might be OK, but those companies with eProm flashers claim they must recondition the ESL completely as some of the Chinese motors are no good (?) and in my case I did not know aliexpress could have even sold me the tool for removing those four holding pins to the lid, so I drilled the pins out, in that case the company tells me I am up for a new lid and $44!
 

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Registered
2005 CLK320
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493 Posts
Thanks, Paul. Please tell me if SDS means "Star"? I have an iCarsoft MB2 diagnostic, but that one only still gives me the A25646 "Implausible signal received" error message. Problem is, my ESL with the new motor might be OK, but those companies with eProm flashers claim they must recondition the ESL completely as some of the Chinese motors are no good (?) and in my case I did not know aliexpress could have even sold me the tool for removing those four holding pins to the lid, so I drilled the pins out, in that case the company tells me I am up for a new lid and $44!
Yes SDS is Star, not sure about the lid but if you only replaced the motor you should not have to program it.
I would give it a try before you pay sombody for the coding.


Sent from my SAMSUNG-SM-G870A using Tapatalk
 

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Registered
2007 C220 CDI Avantgarde W204
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91 Posts
Discussion Starter #5
Yes SDS is Star, not sure about the lid but if you only replaced the motor you should not have to program it.
I would give it a try before you pay sombody for the coding.


Sent from my SAMSUNG-SM-G870A using Tapatalk
Thanks Paul. Spoke to an "expert" (ex-has been, spirt-drip under pressure) yesterday and he confirmed what I read before, namely that a failing motor will also take the NEC chip down, so if an expert finds the chip has been cleared of data, they replace the chip (Chinese or genuine) and they also claim they replace the ESL with a genuine motor (?). Cost more than AUS$400.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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3,657 Posts
All true. The NEC chip acts as a fuse, when the motor goes bad the excess power draw burns the chip, thus necessities a new ESL.

If you catch the motor going bad in time and preemptively replace it, you should be good for another couple years. But if the ESL totally craps out.... Then it's 50/50 as to replacing the motor will fix the problem.

The NEC chip holds the immobilizer info, including all key hash numbers. The ESL independently verifies the key, so if the EIS says key is valid but ESL says it isn't, tough luck. Both must match before ESL gives command to EIS to turn on terminal 15, 30 and 50.
 

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W221 & Audio Moderator
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As @Deplore said - what seem completely backward is actually what happens. The key's IR is transmitted to the ignition switch, and the ignition switch checks its validity based on the 8 key "tracks" it has stored that can be assigned to the vehicle. The key's "password" is the ran through an algorithm in the ignition switch, and a hash value of the key is produced, and this is forwarded to the ESL. If the is not aware of the key's hash, it responds to the ignition switch not issuing a "start enable" condition, therefore, depending on the switch, the key will not turn, or may turn but not be recognized as valid.

An "emulator" device is common to deal with this. If the ESL is not functioning properly, it not only keeps the steering wheel from turning, but also keeps the vehicle from starting. The emulator device mimics what the ESL does buy answering the ignition switch's (EIS) request for validation of the hash and tells the EIS what it wants to hear, therefore allowing the car to start.

The downside of this (if you consider it one) is the steering wheel lock is effectively disabled, leaving it unlocked in all cases.
 
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