Ford Kuga

 Service Manual

Supplemental Restraint System » Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) - Vehicles Built From: 06/2004
Principles of Operation

SRS Operation

The vehicle is equipped with a DC fired sensing system.

In the event of a severe frontal or three-quarter frontal impact, in excess of a predetermined limit,

the driver and passenger front air bags and safety belt retractor pretensioners will deploy.

In the event of a severe full side impact, in excess of a predetermined limit, either the driver or passenger side air bag, side air curtain (if equipped) and both safety belt buckle pretensioners will deploy.

Air bag deployment will only occur, in the event of a severe collision, when the ignition key is in the RUN position. The passenger air bag deactivation (PAD) switch (if equipped) will deactivate the passenger frontal air bag in the event of a severe frontal impact; it will not deactivate any other deployable device.

RCM

The RCM retains full control of the whole system, providing continual system checks and full diagnostic capabilities. The non-volatile memory stores the diagnostic trouble codes, which can then be downloaded through the data link connector (DLC) to the Ford diagnostic equipment.

In the event of a failure in the vehicle supply during an accident, the RCM provides a backup power supply, sufficient to deploy the air bag(s) for a minimum of 150 ms. The backup power supply is discharged by the RCM within 60 seconds of the battery ground cable being disconnected.

The RCM contains electronic acceleration sensors which measure the longitudinal acceleration and the lateral acceleration and provide both signals to the micro-controller proportional to the amount of acceleration measured. The RCM also contains a safing sensor, which prevents unintentional deployment of the front air bags and safety belt buckle pretensioners and knee air bag (if equipped) in the event of a fault within the electronic acceleration sensor(s). The RCM compares the values it receives from the crash sensor, side impact sensors, safing sensor and the internal electronic sensors. If the deceleration due to a frontal or side impact exceeds a stored threshold value then the RCM triggers the air bags and safety belt pretensioners as required.

Front Crash Sensor

The front crash sensor contains an acceleration sensor, filter, amplifier and an application specific integrated circuit for signal transmitting and is mounted on the radiator grille opening panel  reinforcement. The front crash sensor sends a signal at a level determined by the crash severity to the RCM. The RCM will evaluate the signal against stored data and deploy the frontal air bags and safety belt buckle pretensioners if required.

Both the front crash sensor and the internal RCM longitudinal acceleration sensor must exceed a preset limit to initiate the air bag.

Side Impact Sensor

The side impact sensors are mounted at the base of the B-pillar on either side of the vehicle, to facilitate remote lateral impact sensing. Each side impact sensor contains an acceleration sensor, filter, amplifier and an application specific integrated circuit for signal transmitting. In the event of an impact, in excess of a predetermined limit, the side impact sensor sends a signal at a level determined by the crash severity to the RCM. The RCM will evaluate the signal against stored data and deploy the side air bag on the side the deployment request was initiated. Both the side impact sensor and the internal RCM lateral acceleration sensor must exceed a preset limit to initiate the air bag. The RCM retains control of the side air bags, side air curtains.

Air Bag Warning Indicator

The air bag warning indicator is incorporated into the instrument cluster, together with the automatic detach detect circuit. The air bag warning indicator illuminates for 3.2 seconds at key ON and goes OFF for 4.8 seconds. If the system self-tests OK the indicator will stay OFF, but if there is a fault condition, the air bag warning indicator will come ON again and stay illuminated.

The system is designed to illuminate the air bag warning indicator continuously if the RCM circuit is broken, either by loss of power, ground supply, module disconnect or CAN BUS failure.

Diagnostic evaluation of the SRS should be made through the DLC using the Ford diagnostic equipment to establish the nature of the concern.

Inspection and Verification

Diagnosing Customer Concerns Without Hard DTCs

Diagnosing Customer Concerns with Hard DTCs

Deactivation

Reactivation

Glossary

Principles of Operation