E90, E91 and E60, E61, E63, E64 from 09/2005:

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The ECO valve is actuated directly by the AL control unit. Actuation of the ECO valve remains available in the event of the Active Steering failing. A fail safe function via another control unit is not necessary.

The signals and messages required for control of the power-steering pump are as follows:

Status of the engine from the DME control unit via the PT-CAN
Terminal status of the CAS control unit via the K-CAN
Wheel speeds
Steering-angle rate
Status of yaw-rate control system

The ECO valve in the power-steering pump is not actuated unless terminal 15 is ON and the engine is running.