Name: Automatic transmission control unit (AT)
For car: Mercedes-Benz Viano W639
Article number: (may vary depending on model and year of manufacture)
* A0275459432
* A0054477442
* A0035455732
Other designations:
* Electronic Control Unit (ECU)
* Transmission Control Module (TCM)
Functions:
* Gear shift control
* Monitoring transmission fluid temperature and pressure
* Diagnosis of automatic transmission faults
* Ensuring interaction with the engine and other vehicle systems
Location:
The automatic transmission control unit is usually located under the hood of the car, near the automatic transmission itself or in the engine control unit.
Replacement and repair:
Replacement of the automatic transmission control unit should only be performed by a qualified technician. He must reset the adaptive settings of the automatic transmission and adapt it to the car after installing a new unit.
Signs of malfunction:
A malfunction of the automatic transmission control unit can be manifested by the following symptoms:
* Gear slip
*Hard or delayed gear shifts
* The appearance of fault codes related to automatic transmission
* «limp mode» (limiting driving force or downshifting)