Variable Effort Steering System

Variable Effort Steering System Description and Operation

The Variable Effort Steering (VES) System varies the amount of effort to steer the vehicle as wheel speed changes or lateral acceleration occurs. The electronic brake control module (EBCM) controls an actuator located in the steering rack and pinion. The actuator consists of an electromagnetic coil and a pintle valve. The valve regulates an orifice that bleeds inlet pressure through a return passage to regulate the amount of pressure available for steering assist. The EBCM controls the actuator using 0 to 1.0 Amp. At 0 mph the EBCM supplies 1.0 Amp to the actuator. As the vehicle speed increases the amperage to the actuator decreases. The VES system uses the steering wheel position sensor input to calculate lateral acceleration during abrupt driving maneuvers. The system also uses the antilock brake system (ABS) wheel speed sensor inputs to determine vehicle speed. The EBCM is constantly monitoring these inputs to achieve the desired current to the VES actuator. The EBCM has the ability to detect malfunctions in the VES actuator or the circuits to the actuator. Any malfunctions detected will cause the VES outputs to be disabled, and the actuator will return to an open state. The EBCM will command the driver information center (DIC) to display the SERVICE STEERING SYSTEM warning message via a serial data circuit.