Commander 4WD V8-4.7L VIN N (2006)
Parking Assist Distance Sensor: Description and Operation
SENSOR-PARK ASSIST
DESCRIPTION
Vehicles equipped with the rear park assist system have four park assist sensors (1) installed on the rear bumper fascia. Vehicles with the front park assist
system have six additional sensors installed on the front bumper fascia. Only the membrane (4) of each sensor is visible through a hole in the outer
vertical surface of the fascia. The remainder of each sensor including the sensor mounting bracket, the sensor spacer and the sensor wiring connection is
concealed behind the fascia. A sensor wire harness behind the fascia connects the sensors to the vehicle electrical system.
Each of the sensors is identical in construction and is interchangeable. The electrical circuitry and a communication chip for each sensor is enclosed and
protected within the molded black plastic sensor housing. The housing includes an integral connector receptacle (3) and two integral mounting tabs (2).
The sensor membrane extends from the surface of the sensor housing, and is finished to match the outer surface of the fascia.
A resilient O-ring spacer around the circumference of the membrane isolates the membrane from the openings in the fascia. Each sensor is snapped into
its own dedicated molded plastic mounting bracket. Each mounting bracket is heat-staked to the back side of the rear or front fascia.
The park assist sensors cannot be adjusted or repaired. If ineffective or damaged they must be replaced. The sensors and the spacers are each available
for individual service replacement.
OPERATION
The park assist sensors are ultrasonic transceivers that are completely controlled by the park assist module. The sensors transmit and receive ultrasonic
signals. The sensors each receive battery current and ground in parallel from the module, but are each connected to dedicated individual serial bus
communication circuits to the module.
Each sensor membrane is oscillated, then quieted by the module in a pulsing fashion. While the sensor membrane oscillates, it emits an ultrasonic signal.
This signal will bounce or echo off of objects in the path of the vehicle. While quieted, each membrane receives the echoes of the ultrasonic signals it
and the other sensors have transmitted. The sensors then communicate this echo data over the serial bus lines to the module. The microprocessor in the
module uses the intervals between the ultrasonic transmission and reception data from the sensors to calculate the distance to any obstacles identified by
the ultrasonic echoes.
The hard wired circuits between the park assist sensors and the park assist module may be diagnosed and tested using conventional diagnostic tools and
procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the park assist sensor, the park assist module, or the
electronic message inputs to or outputs from the sensor. The most reliable, efficient, and accurate means to diagnose the park assist sensors, the park
assist module, and the electronic message communication between the sensors and the module requires the use of a diagnostic scan tool.
