Safety and Restraintslink
Last updated: November 20, 2024
Overviewlink
The 2024+ Model 3 is equipped with a Supplementary Restraint System (SRS). The system comprises the following components:
- Restraint Control Module
- Occupant Classification System (OCS)
- Occupancy sensors
- Cabin Radar (not available on LHD China / RHD Thailand / RHD Malaysia vehicles)
- Seat track position sensor (only available for front passenger seat in North American markets)
- Passenger Automatic Locking Retractor
- Impact / Pressure sensors
- Seat belt buckle switch
The SRS is designed to work in conjunction with the seat belts. These devices supplement, but do not replace, the protection afforded by the seat belts.
Important
Seat belts are proven to be the single most effective safety device in a vehicle, and should always be worn. Properly worn seat belts ensure that the occupant is seated in the optimum position to benefit from the full effectiveness of the airbags and seat belt pretensioners.
The airbags and seat belts safely dissipate the occupant’s kinetic energy during an impact. The amount of kinetic energy airbags must absorb depends on the velocity of the vehicle and the mass of the occupant. Advanced multi-stage airbags are able to adjust the energy absorption for different speeds or passenger sizes. In North American markets, the Occupant Classification System (OCS) and seat track position sensor give an indication of the passenger mass and location while crash accelerometer and pressure measurements allow for an understanding of the impact speed. The information is continually fed into the Restraint Control Module (RCM) where, in the event of a crash, it can determine the appropriate energy absorption needed from the seat belts and airbags.
Location of occupancy sensorslink
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| North America Market Vehicles |
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| EMEA and APAC Market Vehicles |
Note
Vehicles in the North American markets are equipped with OCS and STP (seat track position). LHD China / RHD Thailand / RHD Malaysia vehicles are NOT equipped with cabin radar due to homologation reasons.
Location of Impact Sensorslink
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| EMEA and APAC Market Vehicles |
Note
Vehicles in both APAC and EMEA regions are equipped with active hood (pedestrian protection system).
Location of Airbags and Seatbelt Load Limiterlink
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| EMEA and APAC Market Vehicles |
Seat belts in the front row are equipped with a variable load limiter, which adjusts the amount of energy that the seat belts absorb from the occupant. To minimize the risk of occupant injury, the load limiter can be deployed to lessen the maximum tension in the seat belts. When load limiters are deployed the energy absorbed by the seat belts is decreased, which allows the airbags to absorb occupant energy more effectively, and thus airbag effectiveness can reduce the reliance on seatbelts to restrain occupants. The system is only deployed in frontal impacts where the airbags are most effective. In cases with only lateral motion or any rear impact, the seat belts absorb as much energy as possible.
Seat belt pretensioners are used to remove slack from the seat belt which helps to absorb occupant energy. Front row seats have shoulder and lap belts with pyrotechnic retractors located in the lower B-pillar trim and lap pretensioners mounted to the seat frame. Second row seats have a shoulder belt with a pyrotechnic retractor. The middle seat does not have a pretensioner.
The first row and second row outboard occupants are protected in crashes with lateral motion (side, angled, or offset type crashes) by side curtain airbags. The curtain airbags deploy down from the upper trim area. Seat airbags inflate from the outboard seat bolsters to soften occupant hip and torso contact with the door trim in the first row. A far side airbag is equipped in the driver's seat and designed to prevent injuries from torso contact with the center console and contact with a passenger. North American market vehicles are equipped with knee airbags. In all frontal cases, when a belted occupant is seated in the passenger seat, and the seat is forward of a pre-determined point in seat track travel (closer to the airbag module), the passenger knee airbag will not deploy.
In the event of a collision with the drive rail on, the pyrotechnic fuse is deployed to isolate vehicle from high voltage battery. All crash modes (including front, side, rear or roll), which exceed programed threshold will trigger the pyrofuse. The fuse disables high voltage by breaking continuity.
All deployable safety systems such as airbags and seat belt pretensioners are single use pyrotechnic devices and must be replaced after deployment. All partially-deployed devices (except load limiters) will completely dispose of their pyrotechnic component shortly after pretensioner deployment. Seat airbag deployment will require a full seat replacement in the event of deployment.
Warning
While deployed safety devices are designed to be inert after a crash to protect occupants and first responders, any pyrotechnic device should be handled with all proper procedures and care according to the vehicle Service Manual.
Airbag Deployment Situations - Drive Rail Onlink
The Supplementary Restraint System (SRS) is designed to deploy safety devices in only specific conditions. An overview of deployment cases is listed below to help understand expected system behavior.
- Flat frontal impact (low speed): Impact below a certain speed (20MPH) where deceleration is above calibration threshold with force directed mostly along the direction of travel. The restraint control module will deploy pyrotechnic fuse, all pretensioners, knee airbags, load limiter selectors, and stage 1 front body airbags. To avoid stress on the occupant, stage 2 is not deployed and goes to disposal to protect occupants and first responders. Side airbags are NOT deployed. The RCM continues to monitor for any additional impacts, and can still deploy remaining systems in any later side or rollover.
- Flat frontal impact (high speed): Impact velocity above a certain speed </(20MPH) with force directed mostly along the direction of travel. The same systems are deployed as a low speed frontal, but front airbags deploy both stage 1 and stage 2 for faster positioning and greater stiffness. The RCM will use information about the mass of occupant to determine the appropriate deployment strategy. The front airbags also deploy the active vents, if equipped, to lessen absorption energy.
- Angled frontal impact (high speed): Impact velocity above a certain speed (20MPH)and lateral movement is detected. The safety system will deploy the safety components to absorb maximum energy from the occupant. Pyrotechnic fuse and airbags (front, knee, side, and curtain) are deployed unless suppressed by the occupant classification system. Pretensioners will fire if the seat belt buckles are latched. Front airbags stage 1, stage 2 and active vent, if equipped, deployment or disposal is dependent on occupant size. The front seat load limiter selector is deployed.
- Side impact: Pyrotechnic fuse, all pretensioners, seat side air bags, and curtain airbags are deployed if a side impact is detected. Front airbags are not deployed because there is little to no forward deceleration and thus no forward force to absorb. The RCM continues to sense for a frontal impact and can deploy additional systems if needed.
- Rollover: Pyrotechnic fuse, all pretensioners, and side curtain airbags are deployed based on a roll rate measured by the restraint control module.
- Rear impact: Pyrotechnic fuse and seat belt pretensioners are deployed. Airbags are not deployed because they would deliver energy to the occupant in the wrong direction.
Although the airbags and pretensioners are designed to be triggered electrically, they are pyrotechnic devices and could deploy unexpectedly— even when not connected to an electrical source— if proper transport, storage, and handling methods are not followed.
Warning
Accidental deployment can cause damage and personal injury. Always refer to the Owner's Manual for correct use of the Tesla Restraint System and seat belt systems, and to the Service Manual for correct fitment, repair, and disposal of system components.
Safety and Restraint Indicatorslink
The airbag warning indicator displays for six seconds when the vehicle is switched on as a system check. After the system check, if there is no active alert, the indicator turns off and stays off. If there is an active alert, the indicator turns off for one second and then turns back. Some alerts will latch the light on for the remainder of the drive cycle, while others can clear and the light will shut off.
The front seat belt indicator and chime are controlled by the restraint control module based on input from the Seat Belt Reminder (SBR) switches and the Occupant Classification System (OCS). The passenger seat SBR and the OCS are inputs to the RCM.
The center display shows all occupied and unbuckled seats on a bird’s eye view of the vehicle. The occupancy sensors can be triggered by any object above approximately 30 lbs.
Restraint Control Modulelink
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| Restraint Control Module |
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| Restraint Control Module Location |
The supplementary restraint system is controlled by the Restraint Control Module (RCM), which includes alert detection and warning circuits. 2024+ Model 3 vehicles are built with the universal RCM. This RCM's ECU is referred to as RCM2. Alerts related to this ECU will begin with the prefix of RCM2.
If an alert is detected, an indicator light on the touchscreen UI notifies the driver. Alerts (with the Electronic Control Unit (ECU) prefix "RCM") are also retrievable using Vitals (via Toolbox) or the vehicle's center display in Service mode.
The RCM is calibrated specifically for the vehicle model. It contains accelerometers and gyroscopes to measure forces acting on the vehicle, and circuits for monitoring the condition of all pyrotechnic devices. It is the primary device that commands the deployment of all Tesla Restraint System components. During a deployment, the system runs a current through individual components to trigger the pyrotechnics. Each stage and part has its own independent wire loop for this triggering signal.
The RCM monitors the SRS's electrical components and circuitry when the drive rail is on. The RCM uses an internal six axis inertial measurement unit (IMU) to monitor all 3 angular velocities, as well as 3D velocity and acceleration changes in the vehicle. The module is located under the center console near the vehicle's center of gravity to sample the motion of the entire vehicle and isolate it from chassis and body vibration as much as possible. The module can be affected by jolts or knocks to the center console from passengers in the vehicle.
The acceleration data from the RCM is broadcast on Chassis Controller Area Network (CAN) (primary) and Party CAN (redundant) to other vehicle systems for use in the traction control, stability control, and other dynamic control algorithms. If the internal sensor detects a high acceleration event it looks to data from the satellite sensors to determine the type and severity of the crash. The RCM only deploys safety components if multiple sensor signals are available and agree. When the signals exceed the calibrated values, the restraint control module directs current through the appropriate deployment loops to deploy the airbags and pretensioners, as necessary.
The RCM records certain aspects of the event data when a deployment occurs. The module holds data for a maximum of 3 independent deployment events. The module stores near deploys (a near deploy is an event that almost deploys pyros but does not meet the threshold for a "collision" event") into the record, but those can be overwritten by additional near or actual deployments. If both records have been stored as full deployments, the module will not allow any additional records. The data is only available when pulled using the proprietary Electronic Device Reader (EDR) tool. The system is entirely separate from the data storage on the gateway after a crash is detected.
When deployment occurs, the RCM sends a collision detection CAN message to vehicle controllers which:
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switches on the hazard lights
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unlocks all doors
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unlocks the trunk
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opens windows to vent position
The gateway will:
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initiate a standard log pull
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package the RCM information
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attempt to gather any Automated Emergency Braking or Side Collision Avoidance data from the Driver Assistance System.
The vehicle will also attempt to package these items and immediately upload them to vehicle CAN logs. If this process fails, there is no retry mechanism and the data will have to be pulled manually from Toolbox.
The RCM performs diagnostic monitoring of Tesla Restraint System electrical components and deployment loops for malfunctions while drive rail is on. The module requests the touchscreen to display the airbag warning indicator light if a bad deployment circuit or missing sensor is detected. If the RCM stores a DTC and sends a CAN message, that is stored in the vehicle log.
Occupancy Sensorslink
Cabin Radarlink
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| Cabin Radar (Driver seat occupancy detection) |
Cabin Radar (ICR), located behind the front overhead console, detects occupancy in only the driver's seat. The ICR communicates with the right vehicle controller (VCRIGHT) via Vehicle Controller Area Network (VEH CAN) and sends data to the Autopilot ECU via CAN-FD for logging purposes.
The ICR emits a radio frequency (RF) wave, which bounces off the surroundings and returns to the module. The ICR algorithm then converts the reflected signal's distance and velocity into object or human detection. This detection is based on the object's movement, size, and location.
Cabin Radar is utilized for driver detection globally except for the following countries:
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China
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India
- Philippines
- Thailand
Vehicles in the above regions utilize the resistive pad to detect the driver.
Serviceabilitylink
Note
Avoid placing objects directly in front of the ICR, as this may obstruct occupant detection.
Tip
The Cabin Radar can be identified with the cfg_InteriorCabinRadarType vehicle configuration. Cabin Radar will have the TESLA configuration.
Use VCLEFT_frontOccupancySwitch and VCFRONT_driverPresent to determine if an occupant was in the seat. These are the same signals are used for the resistive pad. When diagnosing issues of the system, use the following terminology:
- False Positive - There is no occupant in the seat, but the system is detecting an occupant.
- False Negative - The seat is occupied, but the system is not detecting an occupant.
A false positive can lead to the vehicle staying powered on with no occupants in the cabin resulting in loss of range, as well as walk away lock not operating at expected. A false negative can lead to the vehicle not turning on when someone is in the cabin.
When investigating complaints about ICR, be sure to check for the state of the door, buckle, and brake pedal pressed.
Occupant Classification Systemlink
In North American vehicles, the front passenger seat features an occupancy sensor that combines the functions of occupancy sensors and offers additional capabilities.
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| Location of Occupant Classification System |
The Occupant Classification System (OCS) is made up of three individual components:
- The Occupant Classification System Electronic Control Unit (OCS ECU)
- A bladder under cushion
- An Automatic Locking Retractor (ALR) sensor
The Occupant Classification System, which is in North American region only, monitors the seated weight on the cushion and ALR sensor signal to estimate the type of occupant sitting in the front passenger seat, and communicates the status to the Restraint Control Module (RCM) using a CAN signal. The RCM uses this signal to determine whether to enable or suppress the deployment of the front passenger airbag and if applicable, corresponding knee airbag. The Occupant Classification System ECU sends a classification to the right side vehicle controller (VCRIGHT) and then to the RCM, where the passenger airbag light state is determined by the RCM's receipt of the OCS classification. The RCM transmits a signal to the car computer requesting the passenger airbag state light (PASS AIRBAG OFF/ON).
If the Occupant Classification Systems detects a non-qualified adult (which includes small children in/out of child restraints or empty seats), the front passenger front and knee airbag is disabled. The intent is to detect child booster or rear facing infant vehicle seat where even stage 1 deployment provides too much energy absorption for these types of occupant.
For Model 3 vehicles that are not configured with an OCS, there is an passenger airbag cutoff switch.
Note
Seat position, occupant size, and weight distribution affect the sensed values. An occupant whose weight is near the classification thresholds can cause the airbag deployment strategy to toggle between regions.
Warning
The Occupant Classification System is calibrated for each individual seat at the factory. Tesla service procedures must be followed when servicing the system or the seat assembly to make sure that the system function is not compromised.
The air bladder measures the bladder pressure on the seat cushion and compare it to stored threshold to determine whether weight is similar to an adult or an child. But to determine whether this is actually an adult or or child seat (weight of child seat and a chile might be similar to that of an adult), the ECU also need ALR switch signal. If the seat belt is pulled further and then ALR switch will give an signal, then the system can determine it is a child seat because it uses much longer seat belt than a person does. That is to say
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weight smaller than stored threshold, it is determined as a child;
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weight bigger than stored threshold and no ALR switch signal, it is determined as an adult;
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with bigger than stored threshold and with ALR switch signal, it is determined a child in child seat;
This occupant size determines if the active vent is used during higher energy collisions. The Active Vent will lower the pressure in the airbag when the occupant is smaller.
Note
The entire seat needs to be replaced if the bladder under the cushion needs replacement, because every seat need to be separately calibrated in seat factory, which we currently can not do in service.
| Front Passenger Seat Occupancy | Passenger Airbag Indicator Center Display - North America | Passenger Airbag Stages |
|---|---|---|
| Seat empty, child seat, or small child | PASS AIRBAG OFF | None |
| Small occupant (~100 lbs) | PASS AIRBAG ON | 1st, 2nd and Active Vent |
| Large occupant (>160 lbs) | PASS AIRBAG ON | 1st and 2nd |
The RCM notifies the occupants of the disable status by displaying the PASSENGER AIRBAG ON/OFF indicator on the touchscreen. If the car computer goes out with the drive rail on, the center display will display the status of the Passenger AirBag.
If an alert is detected, the OCS sends a message to the restraint control module. The RCM responds by sending a command message to the center display to display the Tesla Restraint System airbag indicator.
Resistive Padlink
The resistive pad is utilized in the driver seat for vehicles in regions where Cabin Radar (ICR) is not active.
The resistive pad is utilized in the passenger seat for vehicles in regions where Occupant Classification is not active.
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| Driver Occupancy Sensor |
This illustration depicts the passenger Occupancy Sensor.
Note
The Driver Occupancy Sensor and Rear Passenger Sensors have a similar design.
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| Drive Occupancy Sensor - Circuit |
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| Rear Passenger Occupancy Sensors |
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| Rear Passenger Occupancy Sensors - Circuit |
These occupancy sensors consist of switches distributed throughout the cushion, connected in both parallel and series. The distributed design helps prevent false triggers of the seat belt reminder indicator, which can occur when small items are present.
The first row driver and passenger seat belt telltales are combined together into a single indicator. This symbol is placed on the touchscreen and is visible at all times. All seat belt telltales are displayed as an overhead view of all seats.
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| Seat Belt Telltale |
Seat Track Position Sensorlink
The seat position sensor (STPS) is only on North American market vehicles and is used to determine the distance between the passenger seat and the front airbag. Information from the seat position sensor allows the RCM to disable stage 2 of the airbag if the seat is forward of a pre-determined point in seat track travel (closer to the airbag module). The seat position sensor is a Hall effect sensor, mounted on the outboard seat track of the driver seat. The seat track includes a metal bracket that shunts the SPS magnetic circuit, creating two states of seat position. The shunted state represents a rearward seat position. The non-shunted state represents a forward position where metal is not present next to the sensor. These 2 states are inputs to the RCM.
When the seat position sensor informs the RCM that the state 1 threshold is reached (seat is rearward), the RCM does not disable stage 2. When the state 2 threshold is reached (seat is forward), the RCM disables stage 2 deployment of the driver airbag.
Note
Stage 2 deployment is also disabled if the RCM detects that the sensor is not operating as expected.
The sensor is attached to the seat track with a screw.
Impact Sensors and Front Door Pressure Sensorslink
There are 5 accelerometer type crash sensors contain a sensing device that monitors vehicle acceleration (positive and negative), and 1 pressure sensor inside every door. The crash sensors send data to the RCM. The RCM uses the data from the sensors to determine if a collision is severe enough to warrant any airbag and/or seat belt pretensioner deployment. Data from the front left and right hand accelerometers are compared to determine if the impact contains offset or is angular
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| Angled and Offset Impact |
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| Impact Sensor |
Front Sensorslink
The front sensors detect front and rear impacts.
B-Pillar Sensorslink
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| B-Pillar Sensor Location |
The B-Pillar sensors detect side impacts.
Door Pressure Sensorslink
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| Front Door Pressure Sensor Location |
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| Piezo-Electric Pressure Sensor |
The Piezo-electric pressure sensors mounted inside every door measures the dynamic pressure change caused by deformation of the door caused by side impact. They require a sealed door compartment to work properly.
The inputs from the pressure sensors are processed by the restraint control module to deploy the side airbags and the seat belt pretensioners.
Warning
Always reinstall or replace any plug or tape removed from a door shell when servicing any component inside of the door. The pressure sensors are calibrated to respond to pressure changes within the door in the event of a side impact. Opening more holes in the door creates additional escape paths for air, which diminishes the sensor's ability to accurately detect a side impact, and can negatively affect airbag deployment.
Passenger Seat Track Position Sensorlink
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| Seat Track Position Sensor (North America vehicles only) |
The passenger seat track position sensor is only on North America market vehicles. The seat position sensor sends position data to the RCM to determine airbag deployment strategy. For vehicles equipped with a passenger knee airbag, if the passenger seat position sensor is in the forward position and the occupant is wearing a seat belt, the front knee airbag will not be deployed.
The sensor is secured to the seat track with one screw.
Passenger Automatic Locking Retractor Switchlink
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| Passenger automatic locking retractor switch location |
The automatic locking retractor switch is located in the seat belt retractor housing. The ALR sensor is used in the occupant classification algorithm. When ALR is engaged, the signal tells the OCS there might be a child seat is installed and the OCS tells the RCM to suppress the Passenger Airbag. Elsewhere, the occupant classification is done just by the pressure in the bladder.
Seat Belt Buckle Switchlink
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| Example of Seat Belt Buckle |
Five seat belt buckle switches are fitted to determine the deployment strategy for lap and shoulder pretensioners, and load limiters. The front row seats each contain a shoulder pretensioner, lap pretensioner, and a load limiter. The second row outboard seats contain only shoulder pretensioners. There are not any additional seat belt restraints for the middle seat. For the front passenger seat, the seat belt buckle switch also determines the active vent deployment strategy for larger occupants.
Deployable Restraintslink
Driver Airbagslink
Mounted on the steering wheel, the driver airbag is a multi-stage front airbag that provides protection from impact with the steering wheel and the surrounding dashboard for adults of all sizes. During an impact, the stiffness of the driver airbag is governed by the deployment strategy and is based on the severity of the crash. Stage 1 only will be used for less severe frontal impacts and the stage 2 will deploy in more severe cases to ensure that the airbag is in position early.
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| Driver Airbag Location |
Only on North America market vehicles, there is a single stage driver knee airbag located beneath the steering column in the lower part of the instrument panel. The knee airbag deploys any time the steering wheel airbag deploys. Occupant kinematics are greatly improved by the knee airbag in situations where the occupant is unbelted.
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| Driver Knee Airbag (North America vehicles only) |
Front Passenger Airbagslink
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| 1. Front passenger airbag 2. Knee airbag (North America vehicles only) |
| Front Passenger Airbag and Knee Airbag |
The passenger front airbag is mounted behind the instrument panel on the front passenger side. The passenger airbag deploys through the top of the dashboard trim, and then wraps forward around the dashboard and glove box area. Similar to the driver airbag, the passenger front air bag is multi-stage. The passenger airbag provides protection for occupants based on their size as calculated by the Occupant Classification System (OCS). If the seat is empty, the occupant is determined to be below the weight threshold the airbag is suppressed. The airbag shape differs from the circular driver airbag in that it contains “lateral lobes” or "bullhorns" which are used to help control the lateral and rotational motion of the passenger’s head.
Multi-stage airbags with active vents allow for variable levels of energy absorption during an impact. Normal airbags deliver only one level of energy absorption and deflate. In a dual stage airbag, the controller can activate a second stage after the first to provide additional energy absorption if it detects a more severe impact.
In North America, front passenger airbags also are equipped with an active vent which when deployed will reduce the energy absorbed. The active vent would be used in the case of a smaller occupant to prevent excessive force on the occupant.
If equipped, the single stage passenger knee airbag is located inside the lower part of the instrument panel. Occupant kinematics are greatly improved by the knee airbag in situations where the occupant is unbelted.
In all frontal cases, when a belted occupant is seated in the passenger seat, and the seat is forward of a pre-determined point in seat track travel (closer to the airbag module), the passenger knee airbag will not deploy.
Curtain Airbaglink
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| Curtain Airbag |
The side curtain airbags are located under the headliner trim on the left and right hand sides of the vehicle. They inflate over the full area of the front and rear side windows to form a cushion, protecting the occupant’s head from contact with the window frame or pillar(s) in a side-impact collision. The side curtain airbag deploys downwards from the top and drapes over the entire glass area. The side curtain airbags stay inflated for a few seconds after a collision in case the vehicle rolls over.
Steering Columnlink
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| Steering Column |
The steering column is designed to absorb energy and collapse during frontal collisions, in order to decrease the chance of injury to the driver. The column has 100mm of collapsible travel. A deformable wire adds resistance to the collapsing motion. If the vehicle has been in a collision that caused driver airbag deployment, the column should be inspected to check whether it collapsed.
Seat Mounted Airbaglink
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| Seat Airbag, Left |
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| Seat Airbag, Right |
The side airbags are part of the front and second row seats. The seat side airbags are deployed from the outboard side of the seat, forming a cushion between the occupant and the door, protecting the occupant’s upper torso and pelvis area during a side impact. 2024+ Model 3 vehicles also have a driver seat far side airbag. A single stage airbag located on the inboard portion on the front driver seat. The far side airbag forms a cushing between the driver and passenger seat during a side impact. Side seat airbags are built into the seat themselves, they are not serviceable. If deployed or damaged, the seats will need to be replaced.
Pretensionerslink
The driver and first row passenger seat belt pretensioners are a dual pretensioner system. The lap belt pretensioners are mounted on the seat, and the shoulder belt pretensioners are integral with the retractors.
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| Lap Pretensioner, Left |
The outboard second row seats each have a single shoulder pretensioner. The initiators of all pretensioners are part of the seat belt pretensioner deployment loop and always deploy simultaneously.
Any time an airbag deployment occurs and the occupant is belted, the seat belt pretensioners are also deployed. These devices are designed to work together to safely absorb occupant energy. The pretensioners will not be deployed if the corresponding seat belt buckle is unlatched. If the signal is not available or faulted at the time of deployment, the RCM assumes seat belts are buckled and the pretensioners will be fired.
The RCM directs current through the deployment loops to the initiator to deploy pretensioners. Current passing through the initiator ignites the material in the canister, producing a rapid generation of gas. The gas produced from this reaction deploys the seat belt pretensioners, which remove slack in the lap and/or shoulder belts. The process is one time only and cannot be reversed. The component needs to be replaced after every deployment.
Load Limiterslink
Seat belts in the front row are equipped with a deployable load limiter, which tunes the amount of energy that the seat belts absorb from the occupant. To minimize the risk of occupant injury the load limiter selector can be deployed to decrease the maximum tension of the seat belts. When the load limiter selector is deployed the force absorbed by the seat belts decreases, which allows the airbags to absorb more occupant energy. The system is only deployed in frontal impacts where the airbags are deployed. In cases with only lateral motion or any rear impact, the seat belts absorb as much energy as possible. The load limiter is contained within the retractor housing.
Pyrofuse Disconnectlink
A pyrofuse disconnect is installed inside the high voltage (HV)battery Ancillary Bay and joins module 2 and 3 of the HV battery. Specific HV battery events, such as over-current, overcharge, over-discharge, in addition to airbag deployment will result in the deployment of the pyrofuse disconnect.
Note
See the \High Voltage Battery Pack Theory of Operation Theory of Operation for more information.
Pedestrian Warning Systemlink
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| Superhorn location |
The PWS (pedestrian warning system) is a legal requirement based on region. The specifics of the requirement (pitch of noise, speed of vehicle, etc) is dependent on which region the vehicle is located. Electric vehicles traveling at slow speeds must emit a noise to warn pedestrians of motion. As soon as a vehicle is put into gear, the speaker emits a noise. Except for North American market, 2024+ Model 3 in other regions are all equipped with super horn, which integrates pedestrian warning function, trumpet horn and siren together. But for North American market, trumpet horn and pedestrian warning system are equipped. For North American vehicles, the Pedestrian Warning System (PWS) encompasses a speaker enclosed in a box at the front right-hand side of the vehicle, located on the front fascia. As of September 2020, the United States requires all new electric vehicles be equipped with the Pedestrian Warning System.
Note
Vehicles in the APAC market (not including Japan) have the ability to turn off the PWS.
For vehicle with superhorn, the warning sounds is produced through the use of Superhorn. Horn signals will be sent from the steering wheel to the left vehicle controller (VCLEFT), based on the signals sent from the gateway to the Audio Digital Signal Processor (ADSP), in order to decide which sound to play by the Superhorn speaker.
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| Superhorn Block Diagram |
Pedestrian Warning System When in Drivelink
The speaker emits a noise while the vehicle is in Drive. As the vehicle accelerates, the noise goes up in pitch. Once the vehicle reaches a speed of 30kph/19mph, the noise begins to fade out. The forward motion noise sounds similar to a spinning fan. The Pedestrian Warning Speaker should only be heard from outside the vehicle and not heard by passengers in the vehicle.
Pedestrian Warning System When in Reverselink
When the vehicle is in reverse, the noise emitted by the PWS needs to be heard at the rear of the vehicle. Because the speaker is located at the front of the vehicle, the noise for reverse is increased and can be heard within the vehicle. The sound while in reverse is more of a tone and intentionally sounds different than the noise in drive. No matter what the speed, the PWS will emit a noise while in reverse.
Pedestrian Warning System Communicationlink
The PWS receives messages via the UI. The drive inverter reports the gear and the speed of the vehicle to the gateway. The gateway then communicates this information to the UI where the audio system then transmits the appropriate noise based off these inputs. The audio system in the vehicle includes microphones, the amplifier that then communicates to all speakers. If there are issues with the Pedestrian Warning System, a good first debug step would be to check the other speakers in the vehicle to pinpoint if the issue is with the audio system as a whole or the Pedestrian Warning Speaker.
Serviceabilitylink
Gateway Configurations
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pedestrianwarningsound
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0 = no speaker
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1 = speaker
Self-Tests
- TEST-BASH_SPK-BASE_X_PED-WARN
This self test simply checks if the speaker is connected to the amplifier.
Pedestrian Protection Systemlink
For 2024+ Model 3, pedestrian protection system, also called "active hood", becomes a common feature for APAC and EMEA regions. The hood will lift up at the hinges to reduce pedestrian injuries when a collision with a pedestrian is detected. The system is mainly made up of：
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Two pressure sensors
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Pressure tube
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Pyro hings
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| Superhorn Block Diagram |
On the basis of the pressure and acceleration, RCM detects whether a collision happens and determines to deploy pyro accordingly, to decrease the severity of injury and protect the pedestrian from becoming more injured in the event of a frontal collision. The system can be activated only when vehicle speed is between 30 and 50kph.
Service & Diagnosticslink
Gateway Configurationslink
| Config | Value | Key | Description |
|---|---|---|---|
| pedestrianWarningSound | 0 | NONE | No pedestrian warning sound available |
| 2 | EXT_SPEAKER_V2 | Pedestrian warning sound emitted from 2nd generation exterior speaker | |
| restraintsHardwareType | 221 | NA_M3B | North America |
| 222 | ROW_ECALL_M3B | Rest of World, with eCall | |
| 223 | ROW_M3B | Rest of World without eCall | |
| 224 | ROW_PEDPRO_M3B | Rest of World without eCall, with PedPro | |
| 225 | EU_ECALL_PEDPRO_M3B | Europe Base with eCall, with PedPro | |
| 226 | EU_PERF_ECALL_PEDPRO_M3B | Europe Performance with eCall, with PedPro | |
| 227 | ROW_PERF_PEDPRO_M3B | Rest of World Performance without eCall, with PedPro | |
| 228 | NA_NO_KNAB_M3B | North America without knee airbags |