Parking Assist Control Module: Description and Operation
MODULE-PARK ASSISTDESCRIPTION
The Park Assist Module (5) is secured within a cavity on the left side of a molded plastic intermediate step assembly (4) located on the rear floor panel (3) under the second row seat cushion. The module is concealed beneath a carpeted trim cover secured by hook and loop fasteners over the step cavity. The inboard side of this cavity also contains the Final Drive Control Module (FDCM) (1) on vehicles that are so equipped. Both modules are connected to the vehicle electrical system through dedicated take outs and connectors of the underbody wire harness (2).
Concealed within the molded plastic park assist module housing (1) is a microprocessor and the other electronic circuitry of the module. The module housing is sealed to enclose and protect the internal electronic circuitry. The module software is flash programmable.
There are four mounting tabs (2 & 3) integral to the module housing that secure the module through two slots and two latch features integral to the floor of the step cavity. Two connector receptacles (4) containing terminal pins that connect the module to the vehicle electrical system are integral to the one side of the housing. One of the receptacles is utilized in vehicles equipped with only the rear park assist system, while both receptacles are used on vehicles equipped with both the front and the rear park assist system.
The park assist module cannot be adjusted or repaired and, if damaged or ineffective, it must be replaced.
OPERATION
The microprocessor in the park assist module contains the park assist system logic circuits. The module uses On- Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the diagnostic scan tool using the Controller Area Network (CAN) data bus. This method of communication is also used for park assist system diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel.
The module provides voltage to each of the park assist sensors located behind the front and rear bumper fascias and to the front and rear park assist displays. The module then monitors return inputs from each of the sensors and the displays on dedicated hard wired data communication circuits. The sensor inputs allow the module to determine when an obstacle is in the front or rear path of the vehicle and enables the module to calculate the relative location of the obstacle, and whether the distance to that obstacle is increasing or decreasing.
Pre-programmed decision algorithms and calibration allow the module microprocessor to determine the appropriate park assist system outputs based upon the inputs received from the park assist sensors and electronic messages received from other modules in the vehicle over the CAN data bus. When the programmed conditions are met the module sends electronic messages to the park assist displays over a dedicated serial bus to obtain the proper park assist system visual and audible outputs. The module also broadcasts electronic messages over the CAN data bus to enable the other electronic features of the park assist system.
The park assist module microprocessor continuously monitors all of the park assist system electrical circuits and components to determine the system readiness. If the module detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC) and sends the appropriate electronic messages to the instrument cluster over the CAN data bus to control operation of certain park assist system audible warnings and textual messages displayed in the cluster reconfigurable display.
The park assist module receives battery current on a fused ignition switch output (run-start) circuit through a fuse in the Junction Block (JB). The module receives ground through a ground circuit and take out of the underbody wire harness. These connections allow the module to be operational whenever the ignition switch is in the START or ON positions.
The hard wired inputs and outputs for the park assist system 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 module, the CAN data bus, or the electronic message inputs to and outputs from the module. The most reliable, efficient, and accurate means to diagnose the module, the CAN data bus and the electronic message inputs to and outputs from the module requires the use of a diagnostic scan tool.