The Variable Effort Steering (VES) system controls the amount of steering effort needed to steer the vehicle as vehicle speed and steering wheel position and turning speed changes. The Body Control Module (BCM) or Electronic Suspension Control (ESC) module, vehicles equipped with Real Time Damping (RTD), controls an electronic Variable Orifice (EVO) solenoid located in the power steering pump's output fluid orifice. The solenoid consists of a pintle valve which moves in and out of the orifice, regulating power steering fluid flow. The BCM/ESC module varies the amount of steering effort by commanding more or less current to the solenoid. At low speeds, no current is commanded and the pintle is fully retracted which provides maximum fluid flow and maximum steering assist for easy turning and parking maneuvers. At high speeds, more current is commanded to the solenoid and the pintle moves closer to the orifice, decreasing fluid flow, providing firmer steering (road feel) and directional stability. The VES system uses the Steering Wheel Position sensor input to calculate lateral acceleration during abrupt driving maneuvers. The system also uses the Vehicle Speed Sensor (VSS) signal from the Powertrain Control Module (PCM) via a class 2 serial data circuit. The control module is constantly monitoring these inputs to achieve the desired current to the EVO solenoid. The BCM/ESC module has the ability to detect malfunctions within the VES system. Any malfunctions detected will cause the EVO outputs to be disabled. Some VES system malfunctions may cause the SERVICE STABILITY SYSTEM warning message to be displayed on the Instrument Panel Cluster (IPC) message center.

NOTE: The BCM/ESC stores the DTCs scan tool data and special functions. However, the scan tool menu to access variable effort steering is located in chassis.