Servotronic valve

The Servotronic controls the degree of assistance provided by the hydraulic steering depending on the vehicle's speed. The flow of hydraulic fluid is restricted to a greater or lesser extent depending on how the Servotronic valve is actuated. Restriction of the flow depends on the current actuating the Servotronic valve.

The Servotronic valve is actuated by the ICM control unit. The signals and messages required for the Servotronic are as follows:

• Driving speed from the DSC control unit via the bus
• Status of the engine from the DME control unit
• Terminal status from the CAS control unit via bus

The Servotronic valve is only activated when terminal 15 is ON and the engine is running. When the speed signal is present, the setting of the nominal current is taken from the characteristic curve.

Fig 1: Identifying Servotronic Valve

Courtesy of BMW OF NORTH AMERICA, INC.