Liftgate Description and Operation

System Description The power liftgate system consists of the following components: Rear gate module Body control module Liftgate position sensor (part of the power assist actuator) Interior liftgate rotary switch Exterior liftgate release switch Liftgate close switch Liftgate latch Liftgate power assist actuator Left and right liftgate object sensors Rear closure hands free module Upper and lower rear closure hands free sensors Keyless entry transmitter Operation The power liftgate operations will be suspended if the rear wiper motor has been activated and wiping the liftgate window, the transmission selector is not in P (park) or if the vehicle speed is above 3KPH The tail lamps will then flash 3X to indicate that the body control module has received a request to power open or power close The power liftgate can be commanded to power open and power close by the following methods: An open or close command from the interior liftgate rotary switch An open command from the exterior liftgate release switch A close command from the liftgate close switch An open or close request by pressing the appropriate button 2x quickly on the keyless entry transmitter (¾ or the MAX modes only) An open or closed commanded by a kicking motion of a foot and lower leg under the rear fascia – Sensor location may vary depending upon make and model, refer to owner’s manual for the location of the sensors. (configured under personalization) The kick projected logo light shows where to perform the kicking motion (Diagnosed in the exterior lighting section) The rear gate module will respond to a request by commanding the liftgate latch to release the liftgate and activate the liftgate motor in the liftgate power assist actuator and raise the liftgate to the open position or to lower and cinch the liftgate closed. Power Liftgate System The rear gate module continuously monitors power liftgate operation and calculates its location and direction of travel from an liftgate position sensor (part of the power assist actuator). One input returns the position of the liftgate relative to the x-axis and y-axis. The rear gate module then uses these 2 inputs together to calculate its angle relative to the liftgate. The interior liftgate rotary switch contains resistors which will incrementally drop the voltage level in the signal circuit as the switch rotated from the OFF position to the ¾ position or the MAX position, the front overhead console assembly will detect the change in voltage and will send a serial data message to the rear gate module which will monitor the x-axis and y-axis as the liftgate is in motion to stop the liftgate parallel to the vehicle roof if the rotary switch is in the ¾ setting or to open fully if the rotary switch is in the MAX setting. The liftgate latch is a bi-directional motor and latch or unlatch operation is the result of the direction of the motor rotation. The rear gate module controls the liftgate latch through the control circuits by supplying power and ground in the appropriate polarity. The motor control circuits are monitored by the rear gate module prior to activation for a high or low condition and during motor operation for an insufficient current flow condition. The unlatch, primary, and neutral switches are part of the liftgate latch and are used by the rear gate module to determine the state of the latch during the process of latching or unlatching and will send the status of the latches to the body control module which is used to determine if the liftgate is closed or ajar. Each of the latch switch signal circuits are supplied battery voltage and monitored within the rear gate module. The latch switches share a common low reference circuit from the rear gate module and when the switch contacts close the signal circuit goes low and the rear gate module determines the switch to be active. The exterior liftgate release switch circuit is supplied battery voltage by the body control module, when the switch is pressed the contacts close and the signal circuit goes low, the body control module will detect the voltage drop and will send a serial data message to the rear gate module requesting the rear gate open request (vehicle unlocked). The liftgate close switch signal circuit is supplied battery voltage by the rear gate module. The switch shares a common low reference circuit from the rear gate module and when the switch is pressed the contacts close and the signal circuit goes low, the rear gate module will detect the voltage drop and will send a serial data message to the body control module requesting the rear gate close request. For vehicles without the optional passive keyless entry, when the exterior liftgate release switch is pressed, the body control module will check the status of the vehicle door locks. If the vehicle doors are locked, the body control module will ignore the signal from the liftgate handle switch. If the vehicle doors are unlocked, the body control module will permit the liftgate to unlatch and power open when the exterior liftgate release switch is pressed. For vehicles with the optional passive keyless entry system, the body control module monitors the proximity of the keyless entry transmitter. If the exterior liftgate release switch is pressed and the keyless entry transmitter is within range, the body control module will send a serial data message to the rear gate module and will permit the liftgate to unlatch and power open. If the doors are locked and the keyless entry transmitter is not within range, the body control module will ignore the signal from the exterior liftgate release switch and the liftgate will not power open. Rear Closure Hands Free Sensor The sensors are located behind the rear fascia (location may vary depending upon make and model, refer to owner’s manual for the location of the sensors) and is designed to detect the motion of the operator’s foot by way of a kicking motion. When the keyless entry transmitter is within 3 feet (1 meter) of the liftgate and the operator kicks his or her foot under the rear fascia, the sensors will detect the motion of the foot and the lower leg and if the procedure has been performed correctly the rear closure hands free module will send a serial data message to the body control module. The tail lamps will then flash 3x to indicate that the command has been received and the body control module and will allow the liftgate to perform the power open or power close function. The rear closure hands free functions can be modified within the Vehicle Personalization: Open and close with the kicking motion Open only with the kicking motion Hands free function disabled Keyless Access function disabled Object Detection The power liftgate system uses an object detection method which consists of liftgate side sensors fixed to both sides of the liftgate near the seal area. The liftgate side sensors consist of an internal fixed resistor and normally open switch contacts which when closed will bypass the resistor. The signal circuit is supplied 5 V through a resistor and monitored within the rear gate module, and during normal power liftgate operation the signal circuit should remain a fixed value. When an liftgate side sensor is presses one of the sensors the contacts close and the resistor is bypassed causing the signal circuit voltage at the module to go low. If the liftgate is being power closed at that time, the rear gate module will command the power liftgate to reverse direction. All power close liftgate operations will be suspended until the obstruction pressing on the liftgate side sensor is removed The rear gate module continuously monitors power liftgate operation and calculates its location and direction of travel from an liftgate position sensor (part of the power assist actuator). One input returns the position of the liftgate relative to the x-axis and y-axis. The rear gate module then uses these 2 inputs together to calculate its position and motion, if the rear gate module detects a current spike and motion reduction in the liftgate position sensor during the power close operation, it will command the liftgate to reverse direction. Manual Liftgate Operation

Note

The interior liftgate rotary switch must be in the ¾ position or the MAX position for the remote keyless entry transmitter (key fob) to command the liftgate, The OFF setting will disable the liftgate release of the remote keyless entry transmitter (key fob) The operator has the option to disable the power liftgate operations by selecting the “OFF” position on the interior liftgate rotary switch. The releasing and cinching for the liftgate latch will function normally, however, the operator must use the exterior liftgate handle switch to activate the liftgate latch and manually pull the liftgate open and push the liftgate closed. All power liftgate operations will be suspended for as long as the liftgate rotary switch is in the “OFF” position.