Circuit Operation

The SSPS system uses inputs from the speed sensor and steering wheel rotation sensor to the SSPS controller to determine the desired amount of power steering assist.

The SSPS control module constantly compares the amount of current flowing through the SSPS actuator to the desired current it has calculated. The SSPS actuator has a pintle that moves in and out of an orifice, regulating power steering fluid flow. The SSPS control module can change the amount of current flowing through the SSPS actuator by varying the output duty cycle. If the SSPS actuator is disconnected, the pintle will be pulled out of the orifice for maximum power steering assist.

The SSPS control module has the ability to detect faults in the steering wheel rotation sensor, the SSPS actuator, or the circuitry to those components. Any default detected will cause the power steering assist to remain at maximum with the pintle in its normally retracted position for all speeds.

When the system is operating normally, increasing the vehicle speed will decrease power steering assist, allowing the driver to have improved road feel and directional stability. When sudden steering wheel turns are made, as in evasive maneuvers, they are detected by the SSPS control module through the steering wheel rotation sensor. When detected, the SSPS control module reduces current to the SSPS actuator, allowing greater power steering assist.