Electronic Pedestrian Protection Hood Hinge Actuator - Operation

OPERATION

The Electronic Pedestrian Protection (EPP) active hood hinge actuators are deployed by a signal generated by the Electronic Pedestrian Protection Module (EPPM) through the right and left hood actuator line 1 and line 2 (or squib) circuits. When the EPPM sends the proper electrical signal to the actuators, the electrical energy generates enough heat to initiate a small pyrotechnic gas generator.

The gas generator is installed in one end of a steel cylinder tube where the piston is sealed to the inside circumference of the tube. As the gas expands, it pushes the piston up the tube, where it actuates the leveraging mechanism of the active hood hinge that cuts the hinge shear rivet and raises the rear edge of the hood panel.

Raising the hood panel following a frontal impact of the vehicle creates additional clearance between the hood and the hard components within the engine compartment. This clearance helps to reduce the severity of injuries that a pedestrian might experience in these situations as a result of harmful contact with those hard parts found just beneath the hood panel within the engine compartment.

The EPPM monitors the condition of the active hood hinge actuators through circuit resistance, and will register a Diagnostic Trouble Code (DTC) for any fault that is detected. The Occupant Restraint Controller (ORC) continually monitors the EPPM and when the EPPM registers a DTC, the ORC will request illumination of the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN). Proper diagnosis of the active hood hinge actuator gas generator and squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.