SPS solenoid valve, function - GF46.50-P-5000-01A
WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.
The P-valve is actuated in cycles with approx. 6V by the ETS, ASR or ESP control module (N47-1, N47-2, N47-5). As vehicle speed increases the current flow reduces and the P-valve opens the control restrictor continuously in accordance with a characteristic (K) defined in the control module. Consequently the oil flow is controlled and also the steering wheel torque.
If the valve is fully energized, (v= 0 km/h), the control restrictor is closed.
Consequently there is no oil flow and the lowest steering wheel torque is adjusted (parking situation).