Theory Of Operation

Under normal vehicle stopped conditions, the Power Liftgate System accepts an input (usually initiated by a customer activated switch) to open or close. Most of the inputs are toggle inputs and the resulting action of either open or close is the opposite of what was or is currently being executed; if the liftgate is closed or closing, it will open; if the liftgate is open or opening, it will close. The requirements of generating a liftgate request apply to the Power Liftgate and the requirements for liftgate movement apply to the Power Liftgate.

The Power Liftgate has the responsibility of authorizing the power operation requests. Liftgate locked/unlocked is determined by the CAN-IHS signal message receive from the Body Control Module (BCM). Liftgate open is determined by not being in the primary or secondary latch position which is derived from the primary and secondary latch position switches. The Power LiftGate Module (PLGM) will remember (including during sleep mode) the last valid (not SNA) state in order to detect a change.

If an input maintains the same active value, such as button pressed for more than 15 seconds, the input will be disabled until the input changes value. The Module that continues to send the (LIN or CAN) bus message is responsible for changing the message to a state of not pressed/not active value until the input is enabled.

If the liftgate is fully closed or closing, then the next movement would be to open. If the liftgate is fully open or opening, then the next movement would be to close. If the liftgate is not fully closed or fully open or closing or opening, and the liftgate position is known, then the movement would be to open. The latch operation power requests that occur during the latch releasing or cinching will be arranged to be recognized after the release or cinch operation (including returning the sector gear to home) has completed.