Power Liftgate Operation

The following is a brief explanation of a normal power open cycle of the power liftgate.

• The power open operation begins with one of the following methods:
  • The LTM  receives a momentary ground signal from the power liftgate control switch.
  • The BCM  receives a signal from the RKE  transmitter (double button press).
  • The LTM  receives a signal from the BCM  (without IA  ) indicating the exterior liftgate handle has been activated.
  • The LTM  receives a signal from the Remote Function Actuator (RFA) module indicating an Intelligent Access (IA) request.
• The MS-CAN  checks the gear selector lever position and vehicle speed status from the MS-CAN  .
• The LTM  supplies power to the unlatch/cinching motor until the sector gear switches indicate end of travel, releasing the power liftgate latch.
• The power liftgate detent switch, primary forkbolt switch and secondary forkbolt switch circuits are monitored for correct latch release states.
• Power is supplied to the drive motor, opening the power liftgate.
• The power liftgate supplies power to the unlatch/cinching motor while monitoring the sector gear switches to return the sector gear to the neutral position.
• When the power liftgate is opening, the position sensor is monitored for liftgate position and velocity. If an obstruction is detected, the liftgate stops.
• The power liftgate full open position is learned by the LTM  during the power liftgate initialization. When the power liftgate reaches the full open position, the LTM  removes the power from the drive assembly actuator motor.
• After the power is removed from the drive motor, the position sensor briefly continues to monitor the position of the liftgate. If excessive movement in the closed direction is detected, power is reapplied to the motor and a continuous chime is initiated and remains on as the liftgate automatically closes. Replace the liftgate cylinders if they cannot support the liftgate in the fully open position after the power is removed from the drive motor.
• If the excessive closing movement is detected on 11 successive power open requests, DTC B201A sets and power liftgate operation is disabled until the DTC is cleared.

The following is a brief explanation of a normal power close cycle of the power liftgate.

• The power close operation begins with one of the following methods:
  • The LTM  receives a momentary ground signal from the power liftgate control switch.
  • The LTM  receives a momentary ground signal from the power liftgate rear control switch (LH rear quarter panel).
  • The BCM  receives a signal from the RKE  transmitter (double press).
• The LTM  checks the gear selector lever position and vehicle speed status from the MS-CAN  .
• The LTM  starts an audible chime.
• After one second of audible chime, power is supplied to the drive motor as the audible chime continues 3 seconds total.
• As the power liftgate is powered closed, the position sensor is monitored for liftgate position and velocity. The power liftgate reverses if an obstruction is detected.
• Also, as the power liftgate is powered closed, the pinch strips are monitored for a pinch condition. The power liftgate reverses if an obstruction is detected by either pinch strip.
• The power liftgate detent switch, forkbolt primary switch and forkbolt secondary switch circuits are monitored for correct latch states.
• When the LTM  receives switch states indicating the secondary latch position is reached, power is supplied to the unlatch/cinching motor to pull the liftgate into the primary latch position. When primary latch position is reached, power is removed from the drive motor.
• When the LTM  receives switch states indicating the primary latch position has been reached (liftgate is fully closed), the LTM  reverses the direction of the unlatch/cinching motor until the sector gear switches indicate the neutral position.