The variable assist magnetic steering system (Magna Steer) varies the driver effort required to steer the vehicle as speed changes. At low speeds, the system requires minimum steering effort for easy turning and parking maneuvers. Steering effort is increased at higher speeds in order to provide the driver with firmer steering (road feel) and directional stability. The EBCM controls a bi-directional magnetic rotary solenoid. The solenoid is located in the steering gear. The EBCM varies the steering assist by adjusting the current flow through the solenoid. The solenoid adjusts the amount of power steering assist in order to achieve a given level of driver effort to turn the vehicle.

Magna Steer accomplishes this by adding or subtracting torque on the rotary input shaft to the power rack and pinion. The amount of steering assist is dependent upon vehicle speed. As the vehicle speed increases, the following actions occur:

As the vehicle speed decreases, the following actions occur:

The scan tool can be used to adjust the amount of steering assist if the customer requests. The steering assist has 3 settings:

The variable effort steering (VES) system uses inputs from the ABS wheel speed sensors and steering wheel position sensor to the EBCM to determine the desired amount of power steering assist.

The power steering pump actuator has a pintle that moves in and out of an orifice, regulating power steering fluid flow. The EBCM can change the amount of current flowing through the actuator. If the actuator is disconnected, the pintle will retract out of the orifice for maximum power steering assist.

The EBCM has the ability to detect malfunctions in the steering wheel position sensor, the actuator or the circuitry to those components. Any malfunction 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 the EBCM steering wheel position sensor detects sudden steering maneuvers, the EBCM reduces the actuator current in order to provide maximum steering assist.

When the Electronic Brake Control Module (EBCM) commands the Magnasteer Actuator ON, B+ is supplied through the EBCM to the MAGNASTEER actuator . Ground/control for the MAGNASTEER actuator is provided through the EBCM to MAGNASTEER actuator controls the amount of current supplied to the MAGNASTEER actuator based on the input from the wheel speed sensors.