General Specifications
| Item | Specification |
|---|---|
| Lubricants | |
| Motorcraft MERCON® Multi-Purpose (ATF) Transmission Fluid XT-2-QDX | MERCON® |
| Fluid capacity (included in pump reservoir fill) | 1.3 L (2.7 pt) (approximate) |
| Power Steering Gear | |
| Type | Rack and Pinion |
| Ratio -Navigator (all) and Expedition vehicles built before 6/2002 | 17:1 |
| Ratio -Expedition vehicles built 6/2002 onward | 20:1 |
| Static steering wheel turning effort Navigator Expedition | 4.0 Nm (35 lb-in) 5.0 Nm (44 lb-in) |
| Turning effort Navigator Expedition | 2.14 kg (4.7 lbs) 2.68 kg (5.9 lbs) |
| Turns of steering wheel (lock to lock -linkage disconnected) | 3.3 |
| Power Steering Purge Vacuum | |
| Minimum vacuum | 67-84 kPa (20-25 in-Hg) |
| Power Steering Pump | |
| Flow (Navigator) | 3.0 gpm ± 0.2 @50psi and 2,500 rpm |
| Flow (Expedition) | 3.0 gpm ± 0.2 @50psi and 1,000 rpm 2.5 gpm ± 0.2 @50psi and 2,800 rpm |
| Minimum capacity | 1.6 gpm @750 psi and 500 rpm |
| Relief pressure | 1,300-1,480 psi |
Table Caption: This table details specifications for power steering systems in Ford Navigator and Expedition vehicles, including fluid types, gear ratios, steering effort, and pump performance metrics. It also provides a capacity for the transmission fluid reservoir.
Steering System
The steering system consists of the following components:
- z power steering pump
- z fluid reservoir
- z steering column
- z steering gear
- z fluid cooler
For information on the power steering pump, steering gear, steering lines and fluid reservoir, refer to Section 211-02 .
For information on the steering wheel, column assembly and intermediate shaft, refer to Section 21104 .
Steering System
Refer to Wiring Diagrams Cell 41 for schematic and connector information.
Special Tool(s)
Principles of Operation
Variable Assist Power Steering (VAPS)
Navigator vehicles include a VAPS system that controls the level of power assistance available to the driver based on vehicle speed. Below 3.2 km/h (2 mph), full power steering assist is provided to lessen steering efforts and increase maneuverability. Between 3.2 km/h (2 mph) and 191 km/h (119 mph), steering assist will decrease gradually at a calibrated rate to raise steering efforts for increased directional stability and greater road feel. Above 191 km/h (119 mph), steering assist is constant.
The 4-wheel air suspension module (4WAS) outputs a pulse-width-modulated (PWM) current to the control valve actuator. The control valve actuator controls the hydraulic valve that determines the amount of hydraulic assist provided to the steering gear. The amount of assistance provided varies with the control valve actuator current, which is based on vehicle speed according to a look-up table internal to the module. The module pulse-width modulates the VAPS actuator current to provide the desired amount of assistance. The amount of hydraulic steering assistance provided by the VAPS subsystem is proportional to the average control valve current.
speed sensor (VSS).
Inspection and Verification
CAUTION: Do not hold the steering wheel (3600) at the stops for an
