Variable Assist Power Steering (VAPS)

Variable Assist Power Steering






The Variable Assist Power Steering (VAPS) system utilizes the existing steering components, a power steering auxiliary actuator (3N803) and a power steering variable assist control adds improved smoothness and handling characteristics.

The VAPS system consists of
- a microprocessor power steering variable assist control
- a power rack-and-pinion steering gear
- a power steering auxiliary actuator
- hose assemblies
- and a high efficiency power steering pump (3A674) for:
- Taurus GL (High Series Only).
- Taurus LX.
- Taurus SHO.
- All Sables (Includes 3.0L and 3.8L).

Note: VAPS is not standard or available on Taurus GL lower series and Police vehicles.

The system uses a modified rotary valve in the power steering short rack (3L547) 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, diverting an increasing amount of fluid to the secondary circuit.

The power steering auxiliary actuator is a pressure-balanced variable orifice valve, controlled by a stepper motor-driven linear spool.

The power steering variable assist control module:
- receives signals from a vehicle speed sensor (VSS) (9E731).
Then it signals the stepper motor-driven spool to adjust the opening of the power steering auxiliary actuator.
- performs a diagnostic self-check every 16 milliseconds.
If a concern is detected, the power steering assist control microprocessor deactivates its output signals.
- performs a service diagnostic procedure when activated by the service technician.






VAPS Exploded View