Front Trunklink
Last updated: October 20, 2023
Overviewlink
The Model S front trunk, also called "frunk", is a storage compartment located at the front of the vehicle. The cargo space can be accessed by lifting the hood, which is held closed by the gas struts and the electrically operated double latch system.
Components Descriptionlink
The hood latch is composed of a metallic latch mechanism connected by a cable to a pull-actuator. The latch has three positions: primary (fully closed), secondary (ajar, half-way open), and fully released (able to be lifted open). The hood latch and release actuator are controlled by VCFRONT.
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| Front Trunk Latch - Location |
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| 1. Front Trunk Latch 2. Release Actuator |
| Front Trunk Latch - Components |
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| 1. Latch Pawl 2. Latch Claw 3. Release Lever 4. Open switch (x2) |
| Front Trunk Latch - Latch Assembly |
The hood is held closed by a striker located on its underside. When closed, the striker is engaged inside the latch primary and secondary mechanisms.
When the front trunk is opened from the touchscreen, the mobile application, or the key fob, the primary and secondary position are successively released and the hood can be lifted open to gain access to the front cargo space.
The hood, held closed by the linkage of the gas strut, needs to be manually lifted before it applies enough force to open and hold the hood up. The double latch system and toggle of the struts are designed to prevent the hood from opening when driving.
There is an emergency release button located inside the frunk which will be illuminated for a certain duration post frunk closure.
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| Front Trunk Emergency Release Button |
The front trunk can also be opened by the frunk access post if the vehicle's 12V battery is discharged. The frunk access post leads are located behind the tow eye cover.
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| Frunk Access Post Location | Frunk Jumper Posts |
Component Operationlink
User Interactionlink
There are 5 methods of opening the front trunk:
- Press the front trunk area of the key fob twice within 500ms.
- Touch CONTROLS > FRONT TRUNK on the touchscreen.
- Touch OPEN on the front trunk in the Tesla Tesla Mobile App.
- Press the interior emergency release button.
- If pressed while the vehicle is driving, only the primary latch is released to allow air to pass through.
- If pressed when not driving, both primary and secondary latches are released.
- Apply 12V to the frunk access post (refer to the frunk access post section for further details on the release conditions).
Note
If frunk access post is used to open the front trunk when the vehicle is locked and the alarm active, the alarm will sound.
To close the front trunk, lower the hood to the closed position and then push down gently on both sides of the hood to engage the primary and secondary latches. Do not push at the very edge or very center of the hood. The hood is aluminum and can be damaged if too much force is applied on one small spot.
Warning
Do not drive a vehicle with the hood latch engaged in the secondary position alone. Lift the front edge of the hood to ensure that it is correctly closed.
Speed Limitlink
If the vehicle enters Drive while the frunk is reported as open, the vehicle touchscreen will show a pop-up asking the user to check the front trunk is secured before proceeding with drive. If the frunk is closed while the pop-up is displayed, it will disappear.
If for any reason the front trunk cannot be closed or if the closed status is not detected, then the pop-up can be overriden but will cause the vehicle speed to be limited to 15 mph or 24 kph for the entire drive cycle.
This system is designed to prevent the hood from flipping open by maintaining a low driving speed at which the air won't apply sufficient force to uplift an unlatched hood.
Frunk Latchlink
The front trunk latch is a single component with built-in primary and secondary latches that can be released by a single release actuator, operated by VCFRONT
As the primary and secondary latches share the same release actuator, VCFRONT can issue two types of release command:
- half release to only unlatch the primary
- full release to unlatch both primary and secondary latches
If commanded to perform a half release, the single release actuator will:
- Pull in the release direction for 120ms.
- Pull in the opposite direction for 110ms.
If commanded to perform a full release, the single release actuator will:
- Pull in the release direction for 120ms.
- Pull in the opposite direction for 110ms.
- Pull again in the release direction for 120ms.
- Pull finally in the opposite direction for 110ms.
There are two switches detecting the position of the latch claw, and their states when no actuation is taking place, are classified as:
| Frunk Latch | Switch 1 Electrical state | Switch 2 Electrical state | Switch 1 Mechanical State | Switch 2 Mechanical State |
|---|---|---|---|---|
| Opened | Circuit Closed | Circuit Open | Not Pressed | Not Pressed |
| Closed | Circuit Open | Circuit Closed | Pressed | Pressed |
| Faulted | Circuit Closed | Circuit Closed | Not Pressed | Pressed |
| Faulted | Circuit Open | Circuit Open | Pressed | Not Pressed |
The status of the switches is determined by reading the switch voltage, which is classified as follows:
| Status | Voltage |
|---|---|
| Shorted | 0V - 0.2V |
| Circuit Closed | 0.2V - 0.8V |
| Faulted | 0.8V - 4.2V |
| Circuit Open | 4.2V - 4.8V |
| Disconnected | 4.8V - 5V |
If either of the switches is shorted, faulted, or disconnected for more than 500ms, then the latch status will be set to faulted.
Frunk Access Postlink
Jumper posts are located under the tow hook cap on the front fascia. There are two jumper leads that need to be fished out after removing the tow hook cap. When 12V source is applied, the frunk will open if one of the requirements listed below is met:
- The vehicle battery voltage is below the jump voltage (12.2V).
- The vehicle is unlocked.
The frunk access post will only cause the frunk latch to release if the vehicle is not moving.
Serviceabilitylink
The hood latch status is reported by VCFRONT signal VCFRONT_frunkLatchStatus and can be monitored to diagnose frunk latch related issues. 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. The table below summarizes the frunk latch signal values and their descriptions:
VCFRONT_frunkLatchStatus |
Description |
|---|---|
| 8 "LATCH_FAULT" | The frunk latch switch value(s) indicate either an error with the switch voltage or a sequence identified as a fault. |
| 7 "LATCH_DEFAULT" | Default frunk latch status when initializing the latch state machine. |
| 6 "LATCH_TIMEOUT" | |
| 5 "LATCH_AJAR" | The frunk latch is in AJAR position (primary unlatched but not secondary). |
| 4 "LATCH_OPENING" | The frunk latch is releasing either the primary, the secondary, or both. |
| 3 "LATCH_CLOSING" | Not applicable to single actuator frunk latch. |
| 2 "LATCH_CLOSED" | The frunk latch is closed with the striker engaged and secured. |
| 1 "LATCH_OPENED" | The frunk latch is either fully opened or is in secondary position. |
| 0 "LATCH_SNA" |
The hood release requests can be monitored by viewing the values reported by each request source:
| Request Source | CAN Signal |
|---|---|
| Key fob or key phone request | VCSEC_frunkRequest |
| Interior emergency release switch request | VCFRONT_frunkInteriorRelSwitch |
| Frunk access post request | VCFRONT_frunkAccessPost |
| MCU (Touchscreen) request | UI_frunkRequest |
VCFRONT sets different alerts to report unexpected or special events, listed in the table below:
| Alert | Description |
|---|---|
| VCFRONT_a303_frunkAccessPostActive | An external voltage source is detected at the frunk access post. |
| VCFRONT_a304_frunkReleaseFailed | Frunk failed to open after being commanded to release. |
| VCFRONT_a305_frunkPriOverCurrent | Frunk primary over current. |
| VCFRONT_a306_frunkPriUnderCurrent | Frunk primary under current. |
| VCFRONT_a391_frunkLatchSwitchFault | Unexpected frunk latch switch(es) voltage or switches mismatch. |
| VCFRONT_a463_frunkSensorService | Customer facing version of VCFRONT_a391_frunkLatchSwitchFault with debounce timer. |
The UI also sets an alert when the vehicle enters Drive with the frunk latch opened:
| Alert | Description |
|---|---|
| UI_a004_FrunkOpen | Front trunk primary or secondary latch open when vehicle gear is not Park |
If the vehicle enters Drive with the frunk opened, the vehicle will apply a speed limit of 15 mph or 24 kph for the entire drive cycle (see Speed Limit section for details).