Hybrid Electric Vehicle Training Educator

Park Position Switch

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  • technical details

The park (P) position switch is a button operated by the driver of the vehicle to engage or disengage the electronic park function on the transmission. When the driver selects the park function, an indicator illuminates on the button. When the light is on, the transmission locks the drivetrain so that the vehicle's front wheels cannot roll. Unlock occurs when the shift lever selection is made, requesting forward or reverse. This button replaces the physical P position found on conventional vehicle shift levers.

This determines the vehicle's conditions based on information from various sensors, switches, and electronic control units (ECUs) and activates appropriate shift control in accordance with the driver's selector lever and park (P) position switch.

With this system, when the driver presses the P position switch, the P position control actuates the parking lock actuator located in the transaxle in order to mechanically lock the parking gear, which engages the parking lock.

Figure below illustrates the vehicles components and the computers that control them. The P position switch reports its request to the hybrid vehicle ECU (HV ECU) if conditions are correct for park. The HV ECU then commands the transmission control ECU to operate the parking lock actuator mounted on the transmission. Unlock occurs if conditions are correct as determined by the HV ECU; a command is issued to unlock. This occurs when the shift lever position sensor reports a forward or reverse request from the driver.Park Position Switch Diagram

© 2012 National Alternative Fuels Training Consortium.

Park Position Switch

Park Position Switch