FORD 2004 Expedition v.3 - Manual (Page 166)

• Restraint system warning light and back-up tone.
• The electrical wiring for the air bags, crash sensor(s), safety belt
pretensioners, front safety belt usage sensors, driver seat position
sensor, and indicator lights.
How does the personal safety system work?
The Personal Safety System can adapt the deployment strategy of your
vehicle’s safety devices according to crash severity and occupant
conditions. A collection of crash and occupant sensors provides
information to the Restraints Control Module (RCM). During a crash, the
RCM activates the safety belt pretensioners and/or either one or both
stages of the dual-stage air bag supplemental restraints based on crash
severity and occupant conditions.
The fact that the pretensioners or air bags did not activate for both front
seat occupants in a collision does not mean that something is wrong with
the system. Rather, it means the Personal Safety System determined the
accident conditions (crash severity, belt usage, etc.) were not
appropriate to activate these safety devices. Front air bags are designed
to activate only in frontal and near-frontal collisions, not rollovers,
side-impacts, or rear-impacts unless the collision causes sufficient
longitudinal deceleration.
Driver and passenger dual-stage air bag supplemental restraints
The dual-stage air bags offer the capability to tailor the level of air bag
inflation energy. A lower, less forceful energy level is provided for more
common, moderate-severity impacts. A higher energy level is used for
the most severe impacts. Refer to Air bag Supplemental Restraints
section in this chapter.
Front crash severity sensor
The front crash severity sensor enhances the ability to detect the
severity of an impact. Positioned up front, it provides valuable
information early in the crash event on the severity of the impact. This
allows your Personal Safety System to distinguish between different
levels of crash severity and modify the deployment strategy of the
dual-stage air bags and safety belt pretensioners.
Driver’s seat position sensor
The driver’s seat position sensor allows your Personal Safety System to
tailor the deployment level of the driver dual-stage air bag based on seat
position. The system is designed to help protect smaller drivers sitting
close to the driver air bag by providing a lower air bag output level.
2004 Expedition (exd)
Owners Guide (post-2002-fmt)
USA English (fus)
Seating and Safety Restraints
166