Variable Assist Power Steering (VAPS)

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The Variable Assist Power Steering (VAPS) system uses the existing steering components, a power steering auxiliary actuator and a power steering variable assist control to improve smoothness and handling characteristics.

The variable assist power steering system consists of the following components:
- ride control module
- power rack and pinion steering gear
- power steering auxiliary actuator
- rotary valve assembly (part of power steering short rack)
- pressure and return hoses
- high efficiency, power steering pump
- power steering pump reservoir
- power steering fluid cooler
- necessary wires and connectors









The variable assist power steering (VAPS) system uses a rotary valve in the power rack and pinion steering gear, with two independent hydraulic circuits called the primary and secondary circuits.
- The hydraulic reaction valve uses the power steering assist pressure, in addition to the torsion bar, to provide steering feel (steering wheel torque). The result is less steering compliance and a more linear valve characteristic. Feel and precision both benefit.
- The electronic controller increases effort (feel) with speed by increasing the amount of hydraulic reaction. This improves precision as speed increases because compliance is being reduced.
- The ride control module (RCM) receives inputs from the ABS module and provides the variable current to adjust the opening of the power steering auxiliary actuator valve.
- If a concern is detected, the RCM deactivates its output signals.
- The RCM is programmed to perform an on-board diagnostic procedure when activated by the service technician.