Power Liftgate Control Module - Operation

OPERATION

The microprocessor-based electronic Power Liftgate Module (PLGM) (also known as the Power Liftgate/PLG control module) contains the electronic logic circuitry and software that is used to monitor the numerous switch and sensor inputs and control the outputs that operate and provide the various electronic features of the power liftgate system.

In addition, the PLGM receives electronic message inputs from and shares its hard wired switch and sensor resources through electronic message outputs to other electronic control modules in the vehicle over the Controller Area Network (CAN) Interior High Speed (IHS) data bus network. The program logic within the PLGM allows the microprocessor to prioritize all of these inputs and determine the task it needs to perform. The task is then completed by controlling hard wired outputs to the liftgate Power Drive Unit (PDU) and latch mechanisms, which lock, unlock, open and close the liftgate. If enabled through the Electronic Vehicle Information Center (EVIC) customer programmable features, the PLGM also provides a hard wired output that controls the power liftgate warning chime unit.

The PLGM is powered by a fused B(+) circuit and is grounded at all times so that it can operate the liftgate regardless of the ignition switch position. The module monitors both active and stored Diagnostic Trouble Codes (DTC) through On-Board Diagnostics (OBD) and communicates with a diagnostic scan tool using the CAN data bus.

The PLGM uses adaptive memory that allows the power liftgate system to learn and adapt to the many variables that may be required to operate the liftgate. If a replacement power liftgate system component is installed or a mechanical liftgate adjustment is made, the PLGM is required to relearn the effort and time to open or close the liftgate. This learn cycle can be initiated only with a diagnostic scan tool connected to the Data Link Connector (DLC). .

The hard wired inputs and outputs of the PLGM 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 between modules and other devices that provide some features of the power liftgate system. The most reliable, efficient and accurate means to diagnose the PLGM 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.