Parking Assist Switch: Description and Operation
PARK ASSIST SWITCHDESCRIPTION
The park assist switch (2) is integral to the lower switch pod (1) in the instrument panel center stack below the heater and air conditioner controls. This switch is a normally open, momentary contact type unit that is actuated by depressing the appropriate rectangular molded black plastic push button on the face of the switch pod. The park assist switch push button is clearly identified with a white International Control and Display Symbol graphic for Parking Aid and the text OFF. An amber Light Emitting Diode (LED) unit is illuminated behind a small clear plastic jewel-like lens in the push button to give a visual indication whenever the park assist system has been manually disabled with the ignition switch in the On or Start positions.
The park assist switch cannot be adjusted or repaired and, is serviced only as a unit with the lower instrument panel switch pod. If the switch is ineffective or damaged, the entire switch pod must be replaced as a unit.
OPERATION
The park assist switch is connected in series between ground and an input terminal of the Electromechanical Instrument Cluster (EMIC). Each time the switch is depressed it provides a momentary ground signal to the EMIC, which the EMIC reads through an internal pull-up. The EMIC responds by sending a park assist switch pressed electronic message to the park assist module over the Controller Area Network (CAN) data bus.
The park assist module responds to each park assist switch pressed message by toggling the status of the park assist system from enabled to disabled, or from disabled to enabled, then sends a park assist system status electronic message back to the EMIC over the CAN bus. The EMIC responds to the park assist module system status message by toggling a transistor that controls a voltage output to the grounded 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 inputs and outputs for the park assist switch may be diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the EMIC, the park assist module, the CAN data bus, or the electronic message inputs to and outputs from the EMIC or the park assist module. The most reliable, efficient, and accurate means to diagnose the park assist switch, the EMIC, the park assist module, the CAN data bus network, and the electronic message inputs to and outputs from the EMIC or the park assist module requires the use of a diagnostic scan tool.