Variable Assist Power Steering (VAPS)

Variable Assist Power Steering

The variable assist power steering (VAPS) system uses the existing steering components, a power steering auxiliary actuator (3N803) and a power steering variable assist control to improve smoothness and handling characteristics.

The variable assist power steering (VAPS) system is standard on all Taurus, Sable models.

The variable assist power steering system consists of the following components:
- generic electronic module
- power rack and pinion steering gear
- power steering auxiliary actuator
- rotary valve assembly (part of power steering short rack (3L547))
- pressure and return hoses
- high efficiency, power steering pump (3A674)
- power steering pump reservoir (3E764), 3.0L (4V) engine
- power steering fluid cooler (3D746)
- necessary wires and connectors Variable Assist Power Steering (VAPS) System Components

The variable assist power steering (VAPS) system uses a solenoid powered steering auxiliary actuator rotary valve in the power rack and pinion steering gear, with two independent hydraulic circuits called the primary and secondary circuits.

During parking and low speed operation, the flow from the power steering pump is routed to the primary circuit by an electrically controlled power steering auxiliary actuator.
As vehicle speed increases, the power steering auxiliary actuator gradually opens, allowing an increasing amount of fluid to the secondary circuit.
This secondary circuit requires more effort to reach a given level of assist.

The power steering auxiliary actuator is a pressure-balanced variable orifice valve, controlled by a solenoid.

The generic electronic module (GEM) receives inputs from a vehicle speed sensor (VSS) (9E731), and provides the variable current to power the solenoid to adjust the opening of the power steering auxiliary actuator valve.
The GEM is programmed to perform a self-diagnostic check every 16 milliseconds.
If a concern is detected, the GEM deactivates its output signals.
The GEM is programmed to perform an on-board diagnostic procedure when activated by the service technician.





Power Rack and Pinion Steering Gear Components

Variable Assist Power Steering, System Components