Front And Rear Park Assist

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

The Front and Rear Park Assist (FRPA) system is active only when the status of the ignition switch is On, the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) position, the manual transmission gear selector lever is in the Reverse R or is not in Reverse and the vehicle speed is less than about 11 kilometers-per-hour (7 miles-per-hour). The system can be manually disabled and enabled by the vehicle operator using the park assist Off push button in the instrument panel switch pod (also known as the Accessory Switch Bank Module/ASBM). In vehicles equipped with this option, the system is enabled from the factory as a default.

Reasons for disabling the system include trailer towing and off road use. With a trailer attached to the vehicle the audible and visual FRPA alerts would be incessant whenever the gear selector lever was in the Reverse (R ) position due to the proximity of the trailer to the rear of the vehicle. Similarly, operating the vehicle off road may cause the FRPA alerts to become distracting due to the proximity of large trees or boulders and the extreme front and rear approach angles that may be encountered while maneuvering on off road trails or terrain.

When the system is disabled, a PARK ASSIST SYSTEM OFF graphic and textual message will appear in the EVIC display of the Instrument Cluster (IC) (also known as the Instrument Panel Cluster/IPC) at the beginning of each ignition On cycle, whenever the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) positions, or whenever the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions. When the system is enabled, a PARK ASSIST SYSTEM ON graphic and textual message will appear in the EVIC display of the IC at the beginning of each ignition On cycle, and a PARK ASSIST READY graphic and textual message will appear in the display whenever the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) positions and the vehicle speed is less than about 11 kilometers-per-hour (7 miles-per-hour), or whenever the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions and the vehicle speed is less than about 11 kilometers-per-hour (7 miles-per-hour).

The microcontroller based, 10 channel Park Assist Module (PAM) (also known as the ParkTronic System/PTS module) is the central component of the FRPA 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 EVIC display, calculates and communicates the proper audible outputs to the Radio Receiver Module (RRM) (also known as the radio or the head unit), 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 PAM operates on battery voltage received through a fused ignition (run) fuse in the Power Distribution Center (PDC) and is grounded through a take out of the body wire harness secured to the body sheet metal.

Six ultrasonic park assist sensors in the front bumper fascia and four sensors in the rear bumper fascia allow the FRPA system to locate and identify the proximity of nearby obstacles. These sensors each generate ultrasonic sound pulses when triggered by the PAM, then signal the PAM when an echo of the reflected sound pulses is received. The detection distance range from the front of the vehicle is about 1.2 meters (47 inches), or from the rear of the vehicle is about 2 meters (80 inches). 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 corners of the vehicle.

In vehicles with an automatic transmission, the FRPA has an available autonomous brake warning feature (also known as brake and release). When the transmission gear selector position is Reverse (R ), an object is detected at the rear of the vehicle at a vehicle velocity based distance value and the ultrasonic sensors are capable of detecting an object the PAM sends an electronic brake and release message to the Antilock Brake Module (ABM) over the CAN data bus network. The autonomous brake warning is aggressively performed by the ABM to reduce vehicle speed and pre-fill the brake hydraulic system in an effort to warn and to give the vehicle operator more time to react to a detected object at the rear of the vehicle.

The autonomous brake warning feature is an alert function, not a comfort function; therefore, the brake application will be sharp and sudden to disturb, rather than smooth and discrete. This feature is enabled from the factory as a default, but can be manually disabled or enabled by the vehicle operator using the customer programmable features settings menu of the RRM.

The EVIC display unit provides the vehicle operator with a graphical representation of the vehicle along with numerous illuminated arc sections that indicate the relative location and range of detected objects. The display is visible directly in front of the vehicle operator and operates based upon the electronic message inputs received from the PAM over the CAN data bus. There are three regions at the front or rear of the vehicle designated for arc alerts: Center, Left and Right. The Front Center region consists of five zones, the Rear Center region consist of six zones, while the Right and Left regions at the front and rear both consist of two zones. The zones range from furthest to nearest from the vehicle. The arc sections are illuminated in an amber color until the nearest zone is reached, at which point the arc sections become illuminated red in color.

Meanwhile, the RRM generates audible indications of a detected object by emitting a series of chime tones that grow progressively higher in frequency as the vehicle gets closer to the object. As the vehicle comes within about 30 centimeters (12 inches) of the object, the audible warning changes from a high frequency series of chime tones to a single continuous tone. If the audio system is active when the RRM receives a chime request message from the PAM, the audio output will be muted automatically while the FRPA audible warnings are being generated.

When the PAM monitors a problem in any of the FRPA system circuits or components, it stores a fault code or Diagnostic Trouble Code (DTC) in its memory circuit, sends an electronic message to the EVIC and the EVIC displays a graphic with a SERVICE PARK ASSIST SYSTEM textual message. If the PAM detects that the park assist sensors are inoperative due to an accumulation of road film, mud, ice or snow on the front or rear fascia, the EVIC will display a WIPE OFF FRONT PARK ASSIST SENSORS or WIPE OFF REAR PARK ASSIST SENSORS graphic and textual message. When the system is disabled by the PAM due to a detected external error or influence, a PARK ASSIST SYSTEM DISABLED graphic and textual message will appear in the EVIC display of the IC whenever a new ignition cycle begins and each time the automatic transmission gear selector lever is in the Drive (D ) or Reverse (R ) position or the manual transmission gear selector lever is in the Reverse (R ) or not in Reverse positions.