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2003, W203 (C240)
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Discussion Starter #1
Hello,

I had a small accident at about 40km/h. Several parts at the front were damaged: water / oil cooler, fan, some pipes. The cooling water has leaked. The engine seems ok; there is no damage and you can turn it with a torque wrench.

The problem is that the engine DOES NOT turn when you attempting to start it with the ignition key.
Furthermore, it does NOT accept the gears (except N). If you try for example to switch to D, the lever pops out.
Shortly after the accident the engine was already OFF, and after that it could not be started.
The instrument panel also lights up and indicates no error. The car gets power, because you can turn on the headlights and the radio also works.
The fuses are ok.
I could not read error codes yet.

Is this a locking mechanism of the electronics?

How can i restart the engine?


The car is a gasoline engine, with automatic, year of manufacture: 2003. Now has 143T km in it.


Thank you in advance for your advice,
Daniel
 

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Furthermore, it does NOT accept the gears (except N). If you try for example to switch to D, the lever pops out.
So you are saying that when you switch the ignition on and place your foot on the brake that you cannot move the shifter from neutral? That sounds like the linkage rod between the shifter and transmission is binding. Maybe the accident was more severe than you thought!
 

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Discussion Starter #3
So you are saying that when you switch the ignition on and place your foot on the brake that you cannot move the shifter from neutral? That sounds like the linkage rod between the shifter and transmission is binding. Maybe the accident was more severe than you thought!
I can move the shifter to everywhere, BUT if i move it to "D", it jumps back to "N". The same is true for the other positions as well.
 

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There is nothing in the shifter itself that would do that. But, it is connected to the transmission via a metal shift rod that moves a lever on the transmission housing which actuates a valve and the parking pawl inside the transmission. The "Drive" position of that lever is fully forward, so maybe something shifted in the accident and is blocking it, or bent the rod, etc. If the rod is bent or otherwise misaligned, the shifter may be on park, but the transmission might not and therefore the engine will not start.

This may help explain what I am talking about:

 

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Discussion Starter #5
There is nothing in the shifter itself that would do that. But, it is connected to the transmission via a metal shift rod that moves a lever on the transmission housing which actuates a valve and the parking pawl inside the transmission. The "Drive" position of that lever is fully forward, so maybe something shifted in the accident and is blocking it, or bent the rod, etc. If the rod is bent or otherwise misaligned, the shifter may be on park, but the transmission might not and therefore the engine will not start.

This may help explain what I am talking about:


Thanx for the hint.
Is it worth to try to remove the cable from the transmission control unit ?
 

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You could try that. If the issue is that the transmission is not in park, then that should allow it to start.
 

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Discussion Starter #7 (Edited)
Could it happen, that the transmission or the torque converter is damaged even if there is no visible damage on it ?
You mentioned earlier: "the shifter may be on park, but the transmission might not ".
How is it mechanically possible even if there is no oil pressure in the transmission, that could lock the TC or the clutches ?
 

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The shifter is both mechanical and electronic. It reports the selected gear electronically to other components in the car, but it also activates a physical linkage rod that physically shifts a lever in the transmission. Inside the transmission, that lever does two things. It electronically reports its position to the TCU and also actuates the servos on the valve body. Knowing which gear is selected on the transmission requires two pieces of information to match: The reported gear from the gearshift as well as the reported gear from the TCU. Both of these must be in park before the engine will start. My guess is that the shifter linkage rod is not aligned properly This might be because of the accident. It may have shifted the drivetrain back relative to the body. In this case, the linkage will be trying to push the lever further forward than it can travel. This is why when you try to put the shifter in "D", it bounces back. Also, even with the shifter in P, the transmission might actually be in R. Again, my advice, if you have the skills and experience to do this, would be to check the position of the shifter linkage rod as outlined in that document. If it's misaligned, I can only guess that happened from the accident, in which case the impact was much more severe and damaging than you initially assumed.

And you are correct - with the engine not running, the torque converter is not rotating and thus it is not operating the transmission fluid pump and there will be no hydraulic pressure. I seriously doubt that the torque converter or internal transmission parts are damaged. If they are, your car would likely be totaled with airbags deployed.
 

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Discussion Starter #9
The shifter is both mechanical and electronic. It reports the selected gear electronically to other components in the car, but it also activates a physical linkage rod that physically shifts a lever in the transmission. Inside the transmission, that lever does two things. It electronically reports its position to the TCU and also actuates the servos on the valve body. Knowing which gear is selected on the transmission requires two pieces of information to match: The reported gear from the gearshift as well as the reported gear from the TCU. Both of these must be in park before the engine will start. My guess is that the shifter linkage rod is not aligned properly This might be because of the accident. It may have shifted the drivetrain back relative to the body. In this case, the linkage will be trying to push the lever further forward than it can travel. This is why when you try to put the shifter in "D", it bounces back. Also, even with the shifter in P, the transmission might actually be in R. Again, my advice, if you have the skills and experience to do this, would be to check the position of the shifter linkage rod as outlined in that document. If it's misaligned, I can only guess that happened from the accident, in which case the impact was much more severe and damaging than you initially assumed.

And you are correct - with the engine not running, the torque converter is not rotating and thus it is not operating the transmission fluid pump and there will be no hydraulic pressure. I seriously doubt that the torque converter or internal transmission parts are damaged. If they are, your car would likely be totaled with airbags deployed.
Thanx for the explanation.
In theory, could it be possible, that in case the airbag opens, the onboard electornic just simply prohibit to start the engine (until the error code is removed) ?
 

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No.
 

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Just to add, in case you do get a scanner that can read data, see the position of the shifter, under the ESM program you can test it to see what it actually reports. Also read from TCM and see if their are any discrepancies.

Great insight from rudeney!

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I kind of recall hearing that when the airbag deploys on a Mercedes (at least older ones) that the engine will no longer start. Something about a prefuse or pyrofuse blowing to reduce chance of a vehicle fire.
 

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There are no pre-fuses for the SRS system and it would not affect the engine being able to start in this model. I think this is a matter of shift linkage alignment. BTW, when you insert the key and turn it to the second position, what gear displays on the instrument cluster's MFD?
 
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