Power Liftgate Drive Unit - Operation

OPERATION

The motor, transmission and screw-drive portions of the power liftgate Power Drive Unit (PDU) provide the power and torque required to open or close the liftgate under most conditions. The Hall effect sensors provide the Power Liftgate Module (PLGM) (also known as the Power Liftgate/PLG control module) with both a speed signal and a direction signal. These Hall effect inputs allow the PLGM to monitor and respond appropriately to any irregularities in liftgate travel and or operation. The full-open switch is used to let the PLGM know when the liftgate is approaching the full open position.

The long, large diameter coil spring within the PDU is strong enough to assist in opening and, in combination with the gas-charged lift cylinder on the right side of the liftgate, will support the liftgate in any open position. The short, small-diameter spring provides an initial liftoff that moves the liftgate latch away from the latch striker after the power liftgate latch is initially released.

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