Dakota 2WD V8-4.7L VIN J (2005)
Impact Sensor: Description and Operation
Front
Two front impact sensors (1) are used on this model, 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 Occupant Restraint Controller (ORC). Each front sensor is secured with two screws to the backs of the right and left
vertical members of the radiator support within the engine compartment. The sensor housing has an integral connector receptacle (2), an integral
anti-rotation pin (3), and two integral mounting holes (4) with metal sleeves to provide crush protection.
The right and left front impact sensors are identical in construction and calibration. A label on the sensor is imprinted with an arrow, which should
always be pointed forward in the vehicle. 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 impact sensor. Potting material fills the cavity and a stamped cover (5) is crimped
over the cavity to seal and protect the internal electronic circuitry and components. The front impact sensors are each connected to the vehicle electrical
system through a dedicated take out and connector of the headlamp and dash wire harness.
The impact sensors cannot be repaired or adjusted and, if damaged or faulty, they must be replaced.
The front 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 microprocessor in the Occupant Restraint Controller (ORC).
The ORC microprocessor 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 Diagnostic Trouble Code (DTC) and controls the airbag indicator operation accordingly. 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 voltage in the sensor plus circuit.
The hard wired circuits between the front impact sensors and the ORC may be diagnosed and tested using conventional diagnostic tools and procedures.
However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ORC, the impact sensors, or the electronic message inputs to
or outputs from the impact sensors. The most reliable, efficient, and accurate means to diagnose the impact sensors, the ORC, and the electronic message
communication between the sensors and the ORC requires the use of a diagnostic scan tool.
