Body Closures: Notes
Component Location
| Item | Part Number | Description |
|---|---|---|
| 1 | 14B291 | LTM |
Overview
The power liftgate feature allows power opening or closing of the liftgate by using any of the following:
- instrument panel control switch
- the liftgate button on a RKE transmitter
- exterior liftgate switch (open only)
- rear liftgate switch (close only)
System Operation
System Diagram
Network Message Chart
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Power liftgate mode command | BCM-B | Used by the LTM to disable the power liftgate from the rear liftgate switch and the exterior liftgate switch when the power liftgate is disabled in the message center. |
| RFA power liftgate open/close request | RFA module | Used by the LTM to either open or close the power liftgate. The RFA module sends this message to the LTM when there is a liftgate Intelligent Access (IA) or RKE request. This message is only sent on vehicles equipped With Intelligent Access. |
| Ignition switch position | BCM-B | Used by the LTM to halt the power liftgate operation when the ignition is in the start position. Once the ignition is out of the start position, the power liftgate operation resumes. |
| Selector lever (PRNDL) status | BCM-B | Used by the LTM to inhibit power liftgate operation if the transmission is not in park. |
| Vehicle speed | BCM-B | Used by the LTM to inhibit power liftgate operation if the vehicle speed is greater than 5 kmh (3.1 mph). |
Power Open
The power liftgate power open operation begins when the LTM receives an input from one of the following:
- The LTM receives a momentary ground signal from the instrument panel power liftgate switch.
- The BCM-B receives a signal from the RKE transmitter (double button press).
- The LTM receives a signal from the BCM-B (without Intelligent Access (IA)) indicating the exterior liftgate handle has been activated.
- The LTM receives a MS-CAN message from the RFA module indicating an Intelligent Access (IA) request.
Once the LTM receives an open request, it opens the power liftgate by carrying out the following:
- The LTM 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 LTM 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.
- If a second press of the instrument panel power liftgate switch or a double press of the RKE tramnsmitter 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 or a customer programmed open height, 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.
Power Close
The power liftgate power close operation begins when the LTM receives an input from one of the following:
- The LTM receives a momentary ground signal from the instrument panel power liftgate switch.
- The LTM receives a momentary ground signal from the rear power liftgate switch.
- The BCM-B receives a signal from the RKE transmitter (double button press).
Once the LTM receives an close request, it closes the power liftgate by carrying out the following:
- The LTM checks the gear selector lever position and vehicle speed status from the MS-CAN.
- The LTM starts an audible chime.
- After 1 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, primary forkbolt switch and secondary forkbolt switch circuits are monitored for correct latch states.
- 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.
If any of the power liftgate switches or the button on the RKE transmitter is pressed during a power close, the liftgate stops and holds its position.
Liftgate Latch Manual Release
In the event of a failure with the power liftgate system, the liftgate can still be opened. REFER to Handles, Locks, Latches and Entry Systems Without Intelligent Access (IA) for additional information.