Parking Assist Switch: Description and Operation
The status of the park assist switch is continually monitored by the circuitry within the upper instrument panel switch pod. The switch pod receives
battery voltage at all times on a fused battery feed circuit, and a path to ground at all times through the instrument panel wire harness. The inputs to and
outputs from the switch pod consist of electronic communication with the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab
Compartment Node/CCN) over the single wire Local Interface Network (LIN) data bus.
Each time the park assist switch push button is depressed the switch pod circuitry sends an electronic park assist switch status message input to the
EMIC over the LIN data bus. The EMIC then sends an electronic park assist switch request message to the park assist module over the Controller
Area Network (CAN) data bus. The park assist module responds to each park assist switch request message by toggling the status of the park assist
system from enabled to disabled, or from disabled to enabled, then sends an electronic park assist system status message back to the EMIC over the
CAN data bus as confirmation.
The EMIC responds to the system status message by sending a message to the switch pod over the LIN data bus to control the park assist switch Light
Emitting Diode (LED) unit so that the LED is illuminated with the system disabled and the ignition switch in the ON or START positions, and is
extinguished with the system enabled or with the ignition switch in any position except ON or START.
The hard wired circuits between components related to the park assist switch may be diagnosed using conventional diagnostic tools and procedures.
Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic
controls or communication between modules and other devices that provide some features of the park assist system. The most reliable, efficient, and
accurate means to diagnose the park assist switch or the electronic controls and communication related to park assist switch operation requires the use of
a diagnostic scan tool. Refer to the appropriate diagnostic information.