Method for controlling a drivetrain of a vehicle

A method is provided for controlling a drivetrain of a vehicle, wherein the drive train includes a combustion engine in drive connection with a dual clutch transmission, wherein the dual clutch transmission is provided with a normally closed input clutch, a normally open input clutch, wherein the normally closed input clutch connecting the combustion engine with a first input shaft and the normally open input clutch connecting the combustion engine with a second input shaft and the first input shaft is in operative connection with a connection sleeve, wherein the connection sleeve can be arranged in an engaged and a disengaged position, whereby in the engaged position the connection sleeve enables an operative connection between the first input shaft to a gearwheel and in the disengaged position gearwheel is disconnected from the first input shaft and the connection sleeve is in a disengaged position when the drivetrain is turned off, wherein the method is automatically initiated at start of the drivetrain, and including the steps of; starting the combustion engine, controlling the normally open and the normally closed input clutch to an engaged or semi engaged state such that both the first and the second input shaft reaches a predetermined synchronized speed, and thereafter opening the normally closed input clutch, and when the countershaft sleeve reaches an essentially synchronous speed with the gearwheel engaging the connection sleeve.