2004 Ford Expedition Owner Guide 3rd Printing - Page 167

Seating and Safety Restraints Front safety belt usage sensors The front safety belt usage sensors detect whether or not the driver and front outboard passenger safety belts are fastened. This information allows your Personal Safety System to tailor the air bag deployment and safety belt pretensioner activation depending upon safety belt usage. Refer to Safety Belt section in this chapter. Front safety belt pretensioners The front outboard safety belt pretensioners are designed to tighten the safety belts of the driver and front outboard passenger firmly against the occupant's body during a collision. This maximizes the effectiveness of the safety belts and helps properly position the occupant relative to the air bag to improve protection. The safety belt pretensioners can be either activated alone or, if the collision is of sufficient severity, together with the air bags. Front safety belt energy management retractors The front outboard safety belt energy management retractors allow webbing to be pulled out of the retractor in a gradual and controlled manner in response to the occupant's forward momentum. This helps reduce the risk of force-related injuries to the occupant's chest by limiting the load on the occupant. Refer to Safety Belt section in this chapter. Determining if the Personal Safety System is operational The Personal Safety System uses a warning light in the instrument cluster or a back-up tone to indicate the condition of the system. Refer to the Warning Light section in the Instrument Cluster chapter. Routine maintenance of the Personal Safety System is not required. The Restraints Control Module (RCM) monitors its own internal circuits and the circuits for the air bag supplemental restraints, crash sensor(s), safety belt pretensioners, front safety belt buckle sensors, and the driver seat position sensor. In addition, the RCM also monitors the restraints warning light in the instrument cluster. A difficulty with the system is indicated by one or more of the following: • The warning light will either flash or stay lit. • The warning light will not illuminate immediately after the ignition is turned on. • A series of five beeps will be heard. The tone pattern will repeat periodically until the problem and warning light are repaired. 167 2004 Expedition (exd) Owners Guide (post-2002-fmt) USA English (fus)