Power Liftgate System: Description
Some vehicles are equipped with an automatic opening and closing power liftgate system (Fig 1 ). This power liftgate system is a complex system consisting of many components. Some of these components are the liftgate gear motor assembly, latch assembly, lift gear and rod, liftgate control module, chime/thermistor, full open switch, engage actuator, pinch sensor, liftgate handle switch, overhead console switch, key fob switches (Fig 2 ), pawl switch and ratchet switch.
The power liftgate system has its own door control module, located on the vehicles left body D-pillar behind the trim panel. (Refer to DESCRIPTION ). The power liftgate gear motor assembly is located just above the control module. The latch assembly is located in the bottom center of the power liftgate, below the exterior liftgate handle switch. The power liftgate full open switch, engage actuator, lift gear and rod are part of the liftgate gear motor assembly. The pawl and ratchet switches are part of the latch assembly. The pinch sensor or sensors are located along the right and left sides of the power liftgate, just above the body line. The liftgate handle switch is an power release switch and is located in the rear light bar assembly, just above the license plate. The overhead console switch is an power open and close command switch located in the vehicles overhead console.
Safety is of the utmost concern with the power liftgate system. Software technology has enabled the power liftgate control module to detect resistance to liftgate travel, which allows the power liftgate to stop and reverse direction anytime an obstruction is felt or any of the command switches are operated (only in closing direction). Battery voltage is supplied to the power liftgate system through a 40 amp fuse, located in the Intelligent Power Module (IPM) assembly (Fig 3 ). In the unlikely event that the power liftgate system develops a fault the power liftgate can still be operated manually with a key, just like a standard manual liftgate.
The power liftgate control module communicates on the J1850 Programmable Communication Interface (PCI) Bus Circuit. Therefore, the power liftgate control module can generate and store its own Diagnostic Trouble Codes (DTC). The vehicles Body Control Module (BCM) receives and supplies messages to the power liftgate control module via the PCI bus circuit. A diagnostic scan tool, such as the DRBIII(R) is used to read and troubleshoot these Diagnostic Trouble Codes (DTC). Refer to the Body Diagnostic procedures for a complete list of diagnostic routines.
For additional information refer to Power liftgate Operation. For a complete system wiring schematic refer to Wiring Diagrams. For system operation instructions refer to the vehicles owner manual. Refer to BODY for additional information on liftgate components such as the prop rods, hinges, door alignment and striker alignment.