V70 2.5T AWD L5-2.5L Turbo VIN 59 B5254T2 (2003)
The function of the four-wheel drive system is based in there being a difference in speed between front and rear wheels. This difference in speed can
affect traction performance in certain driving situations. The role of the pretensioning function is to improve traction performance, primarily in starting
off from being stationary, without affecting other properties of the system to achieve this.
The pretensioning function has been achieved by replacing one of the AOC unit suction valves with a new combined relief and by-pass valve, extra oil
ducts in the housing and adapted software in the differential electronic module (DEM).
As before, the electronic feed pump starts as soon as the engine has started. Running the pump at a higher speed than before generates increased oil flow.
The increased oil flow combined with the new relief and by-pass valve results in a pressure increase that can work on the clutch discs. Greater engine
torque can thereby be transferred to the rear axle. The pretensioning function is controlled by software so that it is only activated when necessary.
