I have a mileage of about 43,000 km of the 2013 Mercedes-Benz VITO commercial vehicle, there is a problem: Start hanging D block, the vehicle can not travel.

First, confirm pick Symptom,found hanging D fail to do so the carriage and Guadang abnormal sound transmission instantaneously.

I had purchased the diagnostic system from mbstartool.com:

I used MB Star diagnostic SD Connect C4 rapid detection of vehicles found in the transmission control unit (ETC) stores a DTC 0731: untrusted or transmission gear skid (gear, and stored)

N15 / 3 transmission control unit receives an engine load signal, vehicle speed signal transmission input / output speed sensor signal, the shift by controlling the electromagnetic valve. Combined with fault code analysis possible causes:

1) input / output speed sensor failure;

2) transmission control unit fault;

3) valve to control the transmission line fault between the units;

4) gear clutch slip.

I Have done the following checking:
1. Remove oil pan, ready to swap with the normal vehicle body, and found a large number of iron filings on the oil pan.
2. Remove the valve body, and found there are a lot of iron the body.
3. The presence of iron described internal transmission wear, break down the transmission and found badly worn gear set

I replaced the transmission assembly, and torque converter cleaning (without replacement) and tubing, then test, fault completely ruled out.