Park Assist System: Operation
The park assist system is active only when the ignition switch is in the ON or START positions, the parking brake is released, and the transmission gear selector lever is in one of the following:
- REVERSE position and the vehicle speed is less than 16 km/h (10 mph)
- DRIVE position and the vehicle speed is less than 14 km/h (8 MPH) on deceleration
- DRIVE position and the vehicle speed is less than 18 km/h (12 mph) on acceleration
The park assist system is enabled from the factory as a default but can be disabled or enabled using the personal settings menu of the Electronic Vehicle Information Center (EVIC).
The disable feature is provided for trailer towing purposes. With a trailer attached to the vehicle the audible and visible park assist alerts would be incessant whenever the gear selector lever was in the REVERSE position due to the proximity of the trailer to the rear of the vehicle. When the system is disabled, a park assist icon will appear within the display. On vehicles equipped with an optional EVIC, a PARK ASSIST OFF textual message will appear within the EVIC display of the instrument cluster whenever the gear selector lever is in the REVERSE position.
The microcontroller based park assist module is the central component of the park assist system. It supplies voltage to the park assist sensors, receives and analyzes data from the sensors, calculates and communicates the proper display information to the Instrument Panel Cluster (IPC), performs system diagnostics, and communicates with other electronic modules in the vehicle or with a diagnostic scan tool over the Controller Area Network (CAN) data bus. The module operates on battery voltage received through a fuse in the Power Distribution Center (PDC), and is grounded through a take out of the body wire harness.
Six ultrasonic park assist sensors in the front and rear bumper fascia allow the park assist system to locate and identify the proximity of nearby obstacles. These sensors each generate ultrasonic sound pulses when triggered by the park assist module, then signal the module when an echo of the reflected sound pulses is received. The detection distance range from the rear of the vehicle is about 0.3 meters (11.8 inches) to about 2.0 meters (80 inches), and the detection height range from the ground is about 0.2 meters (7.8 inches) to about 0.8 meters (31 inches). The detection area extends somewhat around both front and rear sides (corners) of the vehicle.
The park assist display, located within the EVIC unit, provides the vehicle operator with a visible warning if the vehicle comes to within about 40 centimeters (31 inches) of the detected object. The display is visible to the vehicle operator only when looking forward and an object is detected within the detection zone. The system will also emit a series of short, intermittent, audible beeps and automatically mute the audio system while the park assist audible warning is being generated, if the audio system is turned ON. The audible warning changes from intermittent beeps to a continuous tone as the vehicle comes to within 30.5 centimeters (12 inches) of a detected object.
When the park assist module monitors a problem in any of the park assist system circuits or components, it stores a fault code or Diagnostic Trouble Code (DTC) in its memory circuit, sends an electronic message to the IPC, and a SERVICE PARK ASSIST SYSTEM textual message is displayed in the EVIC display.
The hard wired circuits between components related to the park assist system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.