Impact Sensor

Refer to COMPONENT INDEX .

Two front impact sensors are used on vehicles equipped with dual front airbags, one on the back of each vertical member of the radiator support. Six side impact sensors are used, three on each side of the vehicle. One acceleration-type sensor is located behind the B-pillar trim of each lower inner B-pillar, one acceleration-type sensor is located behind the C-pillar trim of each inner C-pillar and one pressure-type sensor is located behind the trim panel on the inside of each front door hardware module carrier.

Remote or satellite impact sensors are mounted in various strategic locations of the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the ORC. Sensors at the front of the vehicle provide an additional logic input for use by the ORC to control the front airbags, the seat belt tensioners and, if equipped, the driver Knee AirBag (KAB). Sensors on each side of the vehicle provide an additional logic input for use by the ORC to control the side curtain airbags, seat airbags and the seat belt tensioners. Two types of sensors are used in this vehicle. They are the acceleration-type and the pressure-type described below.

ACCELERATION TYPE 

Remote or satellite acceleration type impact sensors are mounted in various locations in the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the ORC. Sensors at the front of the vehicle provide an additional logic input for use by the ORC to control the front airbags, the seat belt tensioners and, if equipped, the driver KAB. Sensors on each side of the vehicle provide an additional logic input for use by the ORC to control the side curtain airbags, the seat belt tensioners and the seat airbags.

Although the front and side acceleration type impact sensors are similar in appearance and construction, they may not be interchangeable. The front impact sensors may monitor acceleration forces on a different axis than those monitored by the side impact sensors. Each sensor is secured with a single nut to a weld stud in its mounting location.

A front sensor is located on the back of each vertical member of the radiator support below the inboard side of the headlamp housing and have a side acceleration type sensor located near the base of each inner B-pillar and the middle of each inner C-pillar, concealed behind the interior trim.

Each sensor housing has an integral connector receptacle, an integral locator and anti-rotation pin and an integral mounting hole with a metal sleeve to provide crush protection. A cavity in the center of the molded plastic impact sensor housing contains the electronic circuitry of the sensor which includes an electronic communication chip and an electronic acceleration sensor. Potting material fills the cavity and a translucent molded cover is laser welded over the cavity to seal and protect the internal electronic circuitry and components.

The acceleration type impact sensors are electronic accelerometers that sense the rate of vehicle deceleration, which provides verification of the direction and severity of an impact. Each sensor also contains an electronic communication chip that allows the unit to communicate the sensor status as well as sensor fault information to the microcontroller within the ORC.

The ORC microcontroller continuously monitors all of the passive restraint system electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it sets a DTC and controls the airbag indicator operation accordingly. The acceleration type and pressure type side impact sensors for each side of the vehicle are connected in series (daisy-chained) to the ORC. The impact sensors on each side of the vehicle receive battery current and ground through dedicated left and right sensor plus and minus circuits from the ORC. The impact sensors and the ORC communicate by modulating the voltage in the sensor plus circuit.

The front impact sensors are each connected to the vehicle electrical system through dedicated take outs and connectors of the headlamp and dash wire harness, while the side impact sensors are connected through dedicated take outs and connectors of the body wire harness.

The hardwired circuits between the impact sensors and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the impact sensors or the electronic controls and communication between other modules and devices that provide some features of the SRS. The most reliable, efficient and accurate means to diagnose the acceleration type impact sensors or the electronic controls and communication related to impact sensor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

The acceleration type impact sensors cannot be repaired or adjusted and, if damaged or ineffective, they must be replaced.

PRESSURE TYPE 

Two pressure type front door side impact sensors are used on this vehicle, one each for the left and right sides of the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the ORC. Each side sensor is secured with two screws and is sealed by a resilient gasket to a front door hardware module carrier. The sensors are concealed behind the front door trim panel within the passenger compartment.

The right and left front door side impact sensors are identical in construction and calibration. The impact sensor housing has an integral connector receptacle, two integral mounting tabs and an integral hood-like water shield. The water shield extends through a hole in the hardware module carrier into the interior of the door cavity and protects the sensor orifice from contamination. A cavity in the center of the molded plastic impact sensor housing contains the electronic circuitry of the sensor, which includes an electronic communication chip and the pressure sensor.

The housing cavity is filled with a potting material to seal and protect the internal electronic circuitry and components. The pressure type side impact sensors are each connected to the vehicle electrical system through a dedicated take out and connector of the door wire harness.

The pressure type door side impact sensors recognize a side impact in the door area by monitoring changes in pressure within the door cavity. A sudden pressure wave is created as the door collapses during an impact event. Each sensor also contains an electronic communication chip that allows the unit to communicate the sensor status as well as sensor fault information to the microcontroller within the ORC.

The ORC microcontroller continuously monitors all of the passive restraint system electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it sets a DTC and controls the airbag indicator operation accordingly. The pressure type and acceleration type side impact sensors for each side of the vehicle are connected in series (daisy-chained) to the ORC. The impact sensors each receive battery current and ground through dedicated left and right sensor plus and minus circuits from the ORC. The impact sensors and the ORC communicate by modulating the current in the sensor plus circuit.

The hardwired circuits between the pressure type door side impact sensors and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the impact sensors or the electronic controls and communication between other modules and devices that provide features of the SRS. The most reliable, efficient and accurate means to diagnose the pressure type impact sensors or the electronic controls and communication related to impact sensor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

These pressure type door side impact sensors cannot be adjusted or repaired and, if damaged or ineffective, they must be replaced.