Viano 2,2 diesel 2005 converter lock up problem

[thoriceland]

MB[u1] Viano 2,2 diesel 2005 converter lock up problem
I have had my car, Mercedes Benz Viano 2,2 diesel 2005, in a Mercedes Benz dealership garage for two months.
This is, when you put the car into DRIVE and REVERSE.
The torque converter then locks and the car goes forward without touching the accelerator and when you stop at traffic lights, steps on the brake, the car goes dead!
I have had the torque converter replaced twice and once the walve box in the transmission.
I have also tried a new control module for the transmission, which is placed at the front in the safety box on the left side under the hood.
It has also has be tried to cut off all electrics to the auto trans without success!
The car has also been connected to a MB computer to find any fault codes and none appear!
On several occaisions new oil, a correct one for this transmission, has been put in the transmission.
The MB dealer here in Iceland is not able to figure out what the problem is, some of the MB mechanics seam to believe this problem arises from the engine but others do not agree. The car when it is running idle is normal, just as it is supposed to be.
My question is:
1. what it the reason for the converter to lock itself when the transmission is placed into DRIVE or REVERSE?
2. What das unlock the torque converter?
Best regards

 

[Terry_]

To see if it's the lock up clutch causing the problem they would switch it off with star first. They would know from this if the issue lies within the lock up clutch.
To disable the lock up clutch altogether the control solenoid needs to be removed from the valve body. The oil way in the solenoid itself then blocked off. Then refit the solenoid. This will prevent the lock up clutch from working and the only real issue you will notice is slight drop in mpg on long journeys.

 

[Orzowey]

My Viano does the same, need help or fire...UP