Liftgate

Last updated: July 31, 2024

The rear cargo space can be accessed by opening a powered liftgate, which is electrically operated by two powered struts controlled by VCLEFT, and by a latch and cinching actuator controlled by VCRIGHT.

Component Description

Struts

The Model S liftgate is equipped with struts to raise the liftgate. The left-side strut is a spring strut and the right-side strut is a power strut.

The power strut is an electrical actuator driven by VCLEFT and contains two hall sensors to track the position of the liftgate.

Power Strut	Spring Strut

The power motor mates with a planetary gearbox and internal screw to give the power strut extension. The powered liftgate strut also contains two hall sensors for position and velocity feedback to VCLEFT.

The power strut current draw is monitored by VCLEFT. If there is an obstacle in the path of opening or closing, the current draw will increase beyond a threshold. This is one of the methods for liftgate obstacle detection.

Physical and Digital Switches

Touchscreen Control

(Legacy Model S shown)

The trunk actuation can be accessed by opening the CONTROLS menu via the the bottom left-hand side of the touchscreen. The trunk can be controlled by the OPEN button next to the liftgate area as shown on the above screen.

Exterior Release Switch

1. Exterior release switch
(Legacy Model S shown)

The exterior release switch is located directly above the license plate beneath a ledge on the liftgate. It is a simple contact switch with a direct connection to VCRIGHT. The switch completes a path to ground when pressed.

The exterior release switch can be used to open the liftgate if the doors are unlocked.

Liftgate Shutface Button

(Legacy Model S shown)

The liftgate shutface button is located on the underside of the liftgate. The button connects to VCRIGHT and controls the liftgate to close when pressed. It also is used to set the height of opening of the liftgate (see the dedicated section for details).

Interior Liftgate Release Cable

The interior liftgate release cable is located inside the liftgate interior trim. The cable connects directly to the trunk latch and pulling the cable will manually release the liftgate latch.

This component is not customer-facing and is designed to provide Service with a way to manually release a liftgate latch that does not power release.

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Anti-pinch Strips

The anti-pinch strip is located along the sides of the liftgate. The anti-pinch strip consists of two wires encased in the rubber seal. These two wires are connected to VCRIGHT. When an object is pinched, the two wires make contact with each other and the closed circuit is detected by the liftgate control module.

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Liftgate Latch and Striker

1. Liftgate latch 2. Liftgate striker
The striker shown above is for a Legacy Model S

The liftgate latch is on the underside of the liftgate. The striker can be adjusted for alignment. The latch contains a motor for releasing the hook, which is driven by VCRIGHT.

The latch has a cinching feature to power close the liftgate. When the liftgate lowers and the striker engages the latch, the cinching actuator pulls a cable that is attached to a mechanical linkage on the latch. The linkage cinches the liftgate down to its fully closed position.

When the liftgate is open, an indicator icon displays on the instrument panel.

Note

The liftgate cannot be opened when the vehicle is moving. If an attempt is made to open the liftgate, a warning message appears on the instrument panel.

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Liftgate Cinching Actuator

The liftgate cinching actuator is located inside the liftgate body and is controlled by VCRIGHT.

The liftgate cinching actuator contains a cable housing attachment. The cable connects to the closing linkage on the latch, which cinches the latch shut. See the operation section for the description of the latch operation.

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System Architecture

Liftgate module interaction

Note

Only connections relevant to the liftgate are shown. Please consult the harness schematic for an up-to-date view of all connections between body controllers, sensors, and actuators.

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Component Operation

User Interaction

Opening

Opening the liftgate can be done in five different ways:

• Press the liftgate area of the key fob twice within 500ms.
• Press the liftgate button on the Tesla mobile app.
• Touch CONTROLS > REAR TRUNK on the touchscreen.
• If the vehicle is unlocked, press the exterior release button.
• Pull the interior emergency liftgate release cable.

Closing

Closing the liftgate can be done in five different ways:

• Pull down the liftgate and push firmly until it is fully closed.
• Press the liftgate button of the key fob twice within 500m.
• Press the liftgate button on the Tesla mobile app.
• Touch CONTROLS > liftgate on the touchscreen.
• Press the liftgate shutface button.

Note

The power closing feature is temporarily disabled if you leave the powered liftgate open for more than an hour.

Adjusting Opening Height

The liftgate opening height is adjustable and can be set by following these three steps:

1. Open the liftgate and then manually lower the trunk to the desired opening height.
2. Press and hold the liftgate shutface close button for two seconds until you hear a confirmation chime.
3. Confirm that you have set it to the desired height by closing the liftgate and then reopening it.

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Obstacle Detection

While opening, if the liftgate detects an obstacle by an overcurrent on the strut, the chime will sound, the liftgate reverses for a brief moment, and then stops.

While closing, if the liftgate senses an obstruction by overcurrent on the power strut or by the pinch strip, it automatically opens and sounds two chimes.

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Liftgate Latch

The latch consists of several plastic/metal linkages loaded by springs in a metal casing. The latch can be in an open, intermediate (AJAR), or closed position. The animations below give a visualization of the different stages of the latch.

Open

The hook is not in contact with the striker. The liftgate has not been lowered.

Intermediate (AJAR)

The striker (simulated by the red object in the video) makes contact with the latch linkage (black plastic with hook). This pushes the latch linkage, and moves the hook into an intermediate position. A secondary black linkage on the far left moves via a spring to lock the latch linkage in the intermediate position. This ensures that the latch linkage stays in this state after the pressure from the striker is released. The hook will loosely hold the striker in this position.

This position will release a micro-switch, causing the power struts to shut off, and the cinching actuator to engage the latch further.

Closed

Closing is achieved by pulling on the metal linkage at the bottom to move the latch linkage to the fully closed position. This process is known as cinching, and refers to the usual operation of the cinching actuator pulling on the metal linkage via a cable. The latch linkage and hook is held in the closed position by the secondary black linkage, which moves via a spring to lock the hook in place.

Releasing

Releasing the latch is done by moving the secondary black linkage so that it releases the primary latch linkage back into the open position. Since the latch linkage is on a spring, it quickly snaps back into place. In the video, the actuation is done rotating the gear. In the actual liftgate, the gear is driven by a worm drive. Actuation of this white linkage pushes the secondary black linkage back into place.

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Latch Indexing

The latch is indexed by microswitches. The animation shows the secondary black linkage referred to above moving from the open to closed position. In the open position, both microswitches are pushed. In the intermediate position, only one microswitch is pushed. In the closed position, both micro-switches are extended. Thus, the latch can detect which position it is in, and feed back that information to the powered liftgate control module.

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Powered Liftgate

Powered Liftgate End Conditions

The liftgate can reach the end of travel by either reaching the top or the bottom.

When the liftgate is opening from the closed position, the motor drives the white gear via a worm drive to release the latch to the open position. When both microswitches are pushed, the power struts are then activated to open the gate. The liftgate strut will then operate until the end of travel is reached. The top position determining the opening height is configurable. The two hall sensors track the position of the liftage and feed it back to VCLEFT, allowing detection of when the liftgate reaches the top of travel.

When the liftgate reaches the bottom position, it will engage the intermediate position of the latch by pressing down the latch linkage. At this point, one of the micro-switches is released. This sends a signal back to VCRIGHT that the liftgate has reached the intermediate position. At this point, the power struts are shut off, and the cinching actuator is engaged to perform the cinching operation. When the metal linkage is pulled to move the latch to the closed position, the second microswitch is released, notifying VCRIGHT that the latch has completely closed. The cinching actuator is then released, and a spring pulls the metal linkage back to the original position.

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Serviceability

CAN Signals

There are multiple signals providing information on the powered liftgate and liftgate latch logged by the different vehicle controllers. All the signals mentioned in the following sections are logged by messages posted on the Vehicle (VEH) CAN Bus.

Liftgate Latch

The liftgate latch status is reported by VCRIGHT signal VCRIGHT_trunkLatchStatus and can be monitored to diagnose liftgate latch related issue. The latch status is mainly determined by the value of the latch switch(es) but also rely on different conditions to detect potential malfunction in the system operation.

VCRIGHT_trunkLatchStatus	Description
8 LATCH_FAULT
7 LATCH_DEFAULT	Default trunk latch status when initializing the latch state machine.
6 LATCH_TIMEOUT
5 LATCH_AJAR	The trunk latch is in AJAR position (primary unlatched but not secondary).
4 LATCH_OPENING	The trunk latch is performing a release actuation.
3 LATCH_CLOSING	The trunk latch is performing a cinching actuation.
2 LATCH_CLOSED	The trunk latch is closed.
1 LATCH_OPENED	The trunk latch is opened.
0 LATCH_SNA

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