The power liftgate can be operated by any one of the following means:

When approaching the vehicle, the power liftgate can be opened using a keyless entry transmitter. When the liftgate module sees the serial data message that a release is requested, it begins the open sequence. In this open sequence, the liftgate latch is released, allowing the liftgate motor assembly to begin raising the liftgate. Using the exterior liftgate handle to access the vehicle will only cause the liftgate latch to release; the liftgate motor will not open the liftgate in this instance. When open, the liftgate can be closed by either a keyless entry transmitter or the liftgate close switch. When a GMLAN serial data message or switch input is seen, the liftgate module begins the close sequence. The liftgate motor is reversed, lowering the liftgate until it latches into the liftgate latch. Once latched, the latch will cinch the liftgate to a fully closed position.

Power liftgate function will only be allowed if certain operating criteria are met. Any of the following may cause the power liftgate not to function:

The liftgate also receives inputs from 2 object detection sensors. If either of these sensors indicate an object is in the path of the liftgate, liftgate functions will be suspended until the object is removed.

Liftgate Module

The liftgate module controls the liftgate motor, liftgate clutch, and liftgate latch based on various inputs. The liftgate module also performs diagnostics on these inputs and outputs and will disable liftgate functionality and set DTCs should a fault be detected. The liftgate module is secured to the motor assembly at the left rear of the vehicle. The module requires a liftgate position learn procedure be performed when replacing. This allows the module to learn the full open and full closed positions of the liftgate.

Liftgate Motor Assembly

The motor assembly is located at the left rear of the vehicle and contains the liftgate motor, liftgate clutch, hall effect sensor, and the open switch. The motor assembly also provides means to open the liftgate by way of a gear set. During operation, the liftgate motor drives the gear set that raises and lowers the liftgate through a strut rod connected to a lever which is part of the gear set. The liftgate module applies voltage and provides ground to operate the liftgate motor and clutch. When liftgate operation is requested, the liftgate module engages the clutch and begins driving the motor. If a fault were to occur that requires the disabling of liftgate functions, the liftgate module would release the clutch, allowing manual operation of the liftgate. The liftgate module determines the position of the liftgate based on the hall effect sensor and open switch. The liftgate module applies voltage and provides a ground path to power the hall effect switch. As the liftgate is in motion, the hall effect switch rotates, alternately pulsing the applied voltage on each of the 2 hall effect signal circuits. The liftgate module determines the position based on the number of hall pulses, or counts, received. When the liftgate is fully open, the open switch is closed. This provides an input to the liftgate to indicate the liftgate has reached its full open position.

Liftgate Latch

The liftgate latch contains the cinch/release motor, as well as 3 liftgate switches. Each of the 3 switches contained within provide a discrete input to the liftgate module. These switches act as a liftgate open switch, a liftgate ajar switch, and a cinch/release switch. The liftgate module looks at these inputs to determine when the liftgate has cleared the latch during opening and to determine when the liftgate is seated in the latch during closing. When the liftgate open and ajar switches are seen to be closed, indicating a closed liftgate, the liftgate module will command the cinch/release motor to cinch, pulling the liftgate tightly closed. When a liftgate open operation is requested, the cinch/release motor will release, allowing the liftgate to clear the latch and begin opening.

Right/Left Side Upper Sensor

On each side of the liftgate opening is an object detection sensor. These 2 sensors will disable liftgate closing or reverse an already in motion liftgate should an object be seen in the path of the liftgate. The sensors are pressure sensitive sealing strips located on the upper C-pillar of the vehicle. If pressure is applied to either strip, an input will be sent to the liftgate module signifying that an object has been detected.

Liftgate Handle Switch

Located in the liftgate handle is the liftgate handle switch. This switch provides a discrete input to the liftgate to indicate when a liftgate release operation is requested. Opening the liftgate using the handle will not cause the liftgate to automatically raise. Only the liftgate latch is released when using the handle.

Liftgate Close Switch

Accessible only when the liftgate is open, the liftgate closed switch provides a discrete input to the liftgate module to indicate when a liftgate close operation is requested.