Pinch Sensor - Operation

OPERATION

The two pinch sensors (also known as anti-pinch sensors) are tactile sensors that are able to react to the slightest pressure. They are used to provide additional protection against vehicle damage or personal injury caused by obstructions between the liftgate and the liftgate opening of the vehicle. The interior of each sensor contains two electrically conductive polymer material membranes that will close a circuit when the sensor is contacted.

During a close cycle of the power liftgate, if either of the two pinch sensors come in contact with an obstacle, the pinch sensor circuit is closed. The closed sensor circuit provides a sense input to the Power Liftgate Module (PLGM) (also known as the Power Liftgate/PLG control module) indicating there is an obstruction in the path of the closing liftgate. The PLGM will then stop the liftgate close cycle immediately and return the liftgate to the full open position.

The thermistor integral to the right pinch sensor provides a temperature sense input that allows the PLGM to monitor and compensate for extreme temperature conditions and provide proper power liftgate operation. This temperature sense input is only provided when the pinch sensor is an open circuit because, when the sensor is a closed circuit, the thermistor is shorted. As the outside temperature increases, the resistance reading decreases. As temperature decreases, the resistance reading increases.

The pinch sensors are wired in series with the PLGM, so if either pinch sensor becomes a closed or shorted circuit the module will act as though both sensors are closed circuits. Each sensor also contains a diagnostic resistor, which allows the PLGM to diagnose a problem in the pinch sensor circuits and store a Diagnostic Trouble Code (DTC) for any problem it detects.

The hard wired input and output circuits of the power liftgate pinch sensors 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 and communication that provide some features of the power liftgate system. The most reliable, efficient and accurate means to diagnose the power liftgate pinch sensors or the electronic controls and communication related to operation of the power liftgate system requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.